Moving towards perfection

We saw last time the ideal of knowledge in Aristotle, but what is still lacking is the actual knowledge. Now, whereas in Plato there was one overreaching question – how to live a good life – governing whole of his philosophy, Aristotelian philosophy was governed by several questions. First of them might be: ”what is there and what is it like?” The aim of of this question was to find a vision of things and their essences: vision or theoria, which is why this part of philosophy was known as theoretical.

The experience appears to suggest as the first answer to the theoretical question that there are things that change in a number of ways. As we have seen, this viewpoint had been contested by Eleatics, who believed that there was only one existing thing and therefore nowhere that a change could lead to. Aristotle was quick to note that such a standpoint could not be properly handled in a science that assumes the existence of change. Still, he explained that Eleatic arguments could be understood as linguistic confusions. Thus, even if there would be only one existing entity, this entity could have a number of states, between which a change could happen. Furthermore, the Eleatics had at least described this supposed unitary entity with many terms: it was, for instance, either limited or unlimited. Such a description was then something different from the entity itself, and hence, in a sense even Eleatics had to accept multiplicity.

Because Eleatic arguments could then be ignored, we could accept the testimony of our senses and believe in the existence of change. Change, furthermore, seems to involve the existence of multiple states or things. A further question was then how many features one had to assume in order to account for change. Aristotle found Anaxagoras' theory of change insufficient. As we should remember, Anaxagoras had merely pointed out that e.g. a change of food to flesh could occur, because the constituents of flesh were among the constituents of food. Anaxagoras could then just say that constituents of everything were among constituents of everything else: as Aristotle pointed out, this explanation explained really nothing, because it didn't reveal what these constituents were.

Aristotle was then after a determinate number of features involved in change. His predecessors passed onto him two hints of these features. Firstly, many of earlier philosophers had noted that all change happened between two extreme states, like unity and multiplicity or hot and cold: indeed, all change moves from one state to another. Secondly, especially Platonists had assumed that the world of change was constituted by two things: a disordered chaos and an unchanging source of order regulating this chaos.

Now, Aristotle combined these two insights. The first extreme state of any change could be identified with some Platonic source or idea, or as Aristotle preferred to call it, form: a change either started or ended with a state of having some characteristic, such as the characteristic of being a doctor. The other extreme would then undoubtedly be a state of not having a characteristic. Platonic school had called this negative state matter, but Aristotle thought this was more of a confusion. Plato had not noticed a source of some characteristic could not affect a mere lack of itself (e.g. a mere lack of a doctor cannot become an existence of a doctor without anything to cause this generation of a doctor). Instead, change presupposed that something changed and this subject of change remained existent for the whole duration of this change: for instance, a person who is not doctor might become a doctor through proper education. This underlying thing that remained constant throughout any change could then be regarded as a third element in change, and indeed, this is what Aristotle preferred to call matter.

A certain type of change interested Aristotle partircularly, that is, changes that happened, when things were left to their own devices. Such changes could be called natural, and because Greek word for nature was physis, the study of these changes was called physics. Although the modern physics is a descendant of Aristotelian physics, there are certain clear differences. For instance, in Aristotle's physics it is the biological changes that are especially paradigmatic.

As we might remember from Aristotle's notion of sciences in general, any science should try to determine four aspects of the things it studies. Firstly, one ought to look for the conditions required for something: in case of changes one of these conditions was that what remained stable throughout the change or matter from which the result of the change was made. Secondly, one should try to find out what is the essence of what we are studying: in case of natural changes it is especially the essence of the result of the change we are interested in. Thirdly, one should try to ascertain what made the thing investigated: in this case, what initiated the change. Finally, one ought to find out what is the purpose of the investigated thing, and in this case, the purpose of the change. Now, in case of biological changes the aim of the change is often just to preserve the life of the individual or its genus: thus, the purpose and the essence of the change coincide. Furthermore, the initiating factor of the change is either the living being itself or an individual of the same kind. Hence, one could merely speak of two aspects in these cases – matter and essence or form of the biological change – and Aristotle assumes this is true of almost all natural changes.

Besides natural changes, the things of nature are often affected by chance occurrences. In such cases the occurrences themselves usually are natural, but they have unexpected consequences: for instance, it is natural that a stone falls down, but the falling stone may accidentally also hit a person's head and kill her. Aristotle noted that many earlier philosophers had believed all changes to be based on mere chance: for instance, Empedocles had suggested that in the past there had been generated accidentally all sorts of animals – bulls with human head, for instance – and that only some had been able to live and perpetuate their species. Aristotle noted that although nature did show such chance occurrences, clearly all the natural changes were somehow inevitable, unless some other circumstances prevented them from happening. Yet, such changes were not caused by some clockwork mechanism, because they clearly strived for some end, like perpetuation of species.

What then changes in general involve? According to Aristotle, all changes activated some capacities inherent in that which changed: when I start to build a bookshelf, the capacity of the planks and the nails to be reconfigured in some manner is actualised, and when a leaf starts to turn red, its capacity of being red is activated. Yet, in the state of change this activating process is not yet complete: a leaf turning to red is not yet completely red. Instead, the changing object has activated merely its capacity of being potentially something: a leaf turning to red is on its way to becoming red and is in a more essential sense potentially red than it was before. Changes thus differ from activities like seeing which has no other end except seeing itself: a change moves towards some perfection, which is distinct from the change and in which the change itself ends.

Many of the earliest philosophers had supposed that changes required some sort of limitless source from which new thing could proceed – otherwise, the changes would someday cease, when everything that could come to be would have come to be. Aristotle noted that we need not assume such limitless or infinite source of change, because changes could keep on happening between different possible states: e.g. a same object could constantly turn from red to green and from green to red. Aristotle was generally quite sceptical of any infinities. Certainly there were no infinite bodies, he insisted, because in an infinite universe we would have no meaningful way to differentiate between different directions and thus it would be senseless to say that e.g. heavy bodies move downwards. Then again, infinity was an acceptable concept, if it merely referred to some process being capable of indefinite continuation. Thus, time could be infinite in the sense that time could continue indefinitely, division of areas and lines could continue ”infinitely” or indefinitely long – although in a finite universe there could be only finite areas and lines – and no number of objects was the largest (although there was a smallest number).

Aristotle noted that changes could be classified in different manners. In some cases, what is said to change is not actually what changes, but it is only a part of that which changes or a whole, part of which is changing: thus, if a man is moving, his thoughts may be said to move with him, or when an eye is healing, we may say that the body with the eye is also healing. Yet, in all such cases there must be some primary thing that truly changes.

Now, in some cases, change involved a creation of a new entity or then a destruction of something: when I build a house, the house itself did not exist before the building. Aristotle noted that it was a controversial question whether any true creations or desrructions truly occurred, because in a sense, all changes must involve the continuation of existence: new existents (houses) are generated from previous existents (bricks) and not out of nothingness. Still, Aristotle thought, we can speak of generation and destruction when a substantial change happens, like when an elementary stuff is changed into another sort of elementary stuff. Thus, a generation of one substance involves always a destruction of another substance.

In most of the changes, nothing is created or destroyed, but some feature of an existing thing is altered. This feature might be a quality that is not essential to the thing in question – like when a leaf turns red. At other times even the shape of the thing might remain what it is, but the quantity of the thing might change into bigger or smaller – like when a balloon expands. In some cases no feature of the thing changes, but the thing merely moves from one place to another.

Aristotle was also sure that if we ignored creations and destructions, things could change in a primary sense only in these three manners: qualitatively, quantitatively or from one place to another. Things could still change incidentally in other manners: thus, when all childs of a person dies, the person also incidentally stopped being a parent, although no change had happened to her personally. Particularly, Aristotle thought that changes cannot be said to properly change or come to existence or to be destroyed: otherwise, all changes would involve an infinite number of other changes.

The possibility of moving from one place to another suggests the question what places in general are. Clearly a place is not a feature of the body in it: otherwise, another object could not take the place of another (like one leaf cannot take the colour of another leaf). Instead, the place of an object is, primarily, the innermost surface of things embracing the object in question: thus, the place of wine is the inner surface of the bottle where the wine is situated. Secondarily, the place of the object is then any place where any place of the object is situated: thus, because the bottle is in the fridge, the wine may be said to be in the fridge, and because the fridge is in the kitchen, the wine is also in the kitchen. The ultimate place in which everything then is situated is the outer fringe of the universe – remember that Aristotle argued for the finity of the universe, because otherwise we could not situate anything anywhere in a meaningful way.

Although Aristotle thus accepted the idea of an ultimate system of places or space, he was not convinced that space could exist without anything to fill it. Atomists had endorsed the idea of empty space, because they couldn't conceive how anything could move without there being something empty to which it could move. Aristotle noted that the movement could still happen, if the things would just change their places with one another. Furthermore, in empty space nothing could move, according to Aristotle: all motion required some push from other objects, but in an empty space nothing would push an object to move. On the other hand, in empty space all things would move with infinite speed: speed of a thing was, Aristotle suggested, proportional to the resistance of medium in which the movement happened, but in a void with no resistance, the speed would grow impossibly large. It is easy to laugh at such deductions, when we know better, but the Aristotelian notions of movement and space might seem more natural, if we knew nothing of inertia.

In addition to space, movement is also connected with time. Indeed, time appears to be essentially related to change. Even if we were in a dark cave and saw nothing happening, but something changed in our thoughts, we could be certain that time went forward. Time is then, Aristotle suggests, the act of counting out all changes and especially movement: the moment of ”now” moves through various changes and determines what happened before and after and at what rate. Although the counting might be something we humans do, time itself is in another sense not dependent of human beings, because the things counted or the temporal processes would occur even without human beings. Aristotle also suggests that a natural way to measure time would be to use some cyclical and recurring process, like the revolution of planets.

Aristotle was certain from experience that spatial magnitudes form a continuum: that is, e.g. volumes that are next to each other or that have nothing between them have limits that touch one another and that cannot be separated from one another. Aristotle concluded from this definition of spatial continuum that it could not be formed of indivisible points – if point would be continuous with another point, their limits would coincide and be inseparable, and because points have no other limits, but points themselves, the points would actually be identical with one another. Indeed, two points cannot be even immediately next to each other in space, because two different points will have some line between them. Aristotle noted also that if space was a continuum, motion through space must also be continuous (otherwise a moving object could instantly move from one area of space to another separate from the area it had occupied), if motion was continuous, so also the passage of time (because time measures all motions), and if passage of time was continuous, so finally all changes (because time measures also other changes).

Aristotle's idea of continuum was explicitly meant to show why Eleatic and especially Zeno's proofs against the existence of motion were invalid. Zeno had argued that an object couldn't move, because at any one moment it was in some place resting. Aristotle answered that time does not consist of moments, although it is limited by moments: when we divide a process, we find just smaller processes, but no indivisible unit of processuality. The so-called ”now” was then, according to Aristotle, no part of time, but a limit between past and future periods of time.

If Zeno's first argument targeted the idea of motion as consisting of indivisible moments, his other argument tried to combat the idea of continuous movement and time by noting that it involved a movement through an infinite number of points that would take infinitely time. Aristotle noted that although space, moved through by an object, did contain the possibility of being divided into smaller and smaller points with evermore limiting points, these limits did not really stop the motion for any time, unless the object stopped for a moment at such limit point: but the motion would take an infinite time only if the object stopped at every possible limiting point, because the smaller pieces of motion take up smaller periods of time.

We have already seen how Aristotle assumed the existence of changes. Furthermore, he was certain that changes had happened always and would always happen: indeed, because time was for Aristotle a measure of change, no time without change could exist. In addition, changes could not have begun from a generation of moving things, because all changes require something existent: even changes where new entities are formed, such as a construction of a chair, require some previous matter from which the new entity is made. Finally, time of change could not be preceded by a period of eternal rest of all entities: otherwise, there must have been some object hindering the possible changes, and the supposed first change would have to be preceded by the destruction of this hindering element.

Then again, Aristotle also was certain that not all things were changing at any current moment. Qualitative and quantitative changes would end at some time – becoming red when the changing thing had became red and growing at least when the growing thing reached the size of the finite universe. The only change that might continue forever would be motion, but experience appeared to confirm that not all things were moving: for instance, a stone might be restfully lying on the ground. Finally, some things apparently start changing, while others stop changing.

Aristotle also thought it reasonable to assume that all moving and changing things were moved or changed by something: either by some part of themselves or something separate from them. In case of forced changes this seems obvious, but unforced or natural changes seem a different case. Yet, even natural changes (like the fall of a heavy object) could be said to be caused by things that either changed the nature of the thing changing (e.g. the thing that solidified moisture in the clouds to snow that then would naturally fall down) or released the thing from any hindrances to its natural motion (like a person sawing table legs causes a table to fall down). Furthermore, even in the so-called self-moving entities, like animals, one could separate between the moving aspect and the moved aspect. Thus, all changes would be caused by things other than the things changing.

The next question would then be whether all moving things would be moved by some moving thing or whether there could be movements and changes instigated by something immovable: because Aristotle equated nature with the realm of moving and changing things, this immovable would have to be beyond nature. Aristotle approached the question by noting that a moving thing can be said to move another thing only if the original moving thing moves at the same time than the moved thing. Because the moving thing would require then another moving thing to move it, there would at the same limited time be an infinite number of moving things and thus an infinite amount of motion. As Aristotelian universe was limited, such an infinite motion during a limited time appeared an impossibility to him.

Although the consideration of such an unchanging cause of changes would indeed not belong in an investigation of changing things, one still must ponder what sort of changes this primary initiator would cause. Because this initiator does not itself change in any manner, it can initiate only a change that occurs constantly and goes on continuously. Clearly such change cannot be a generation of a new entity, destruction of an old entity, change from one quality to another or growth or diminution of an object, because such changes all have a final limit, beyond which they cannot continue. Neither can it be movement in a straight line, because in a finite universe, such a motion must eventually stop. The only remaining possibility then is that the primary initiator causes something to move around in a circle for eternity.

Most of the things Aristotle has discussed thus far are at the fringe of what nowadays is called physics, and indeed, might be classified as metaphysics.When Aristotle comes to more concrete matters, the more dated his discussions appear. Still, it is worth to look at the cosmology of Aristotle more carefully because of its long-lasting influence. Note that although later generations were to treat Aristotle's natural philosophy as a fully completed system, it was always more of a work in progress – thus, Aristotle knew that there were many open problems, answers to which were merely speculated by Aristotle and his followers.

We have seen that in Aristotelian universe of changing things, some things change sometimes, while others are in a continuous process of change, and more particularly, move in circles. Aristotle explains the difference between these two things by suggesting that the things moving in circles are made of different stuff than the other things, namely, from a stuff that naturally moves in circles. Because of the continuous nature of circular movement, this stuff seems more primary than other sorts of matter.

Aristotle feels also convinced that there is only one sort of matter moving naturally in circles: the circular movement defines this stuff. Still, there can be places in which this stuff is more concentrated than in others. Such spots appear to us as emitting light in comparison with the other heavenly regions. Aristotle also suggests in some passages that these spots are living and perhaps even conscious entities.

Aristotle also thinks that the world of the circularly moving stuff is divided into different layers: this is his attempt to explain the astronomical knowledge of his times. The outermost layer moves in a circle and the concentrated spots are carried by the layer: these spots are what we would call stars, which appear to move around the Earth in one day. This layer and its denizens are the most perfect moving things. Slightly lesser perfect are the spots moving in the inner laeyrs of the circularly moving stuff. The layers themselves move around the Earth, but the movement of the outer layers makes the spots also move within their own layers: this causes the apparently erratic movements of the planets. In the innermost layers the effect of the outer layers apparentyly twindles, because the layers moving the Sun and the Moon move again in a simpler manner. Aristotle also connects this structural difference of the layers with their corresponding levels of perfection: the stars in the outermost layer achieve the highest state of bliss through a simple movement, the planets require more effort to achieve this state and the Sun and the Moon cannot even achieve this level of perfection.

The circling movement of the heavenly stuff requires some fixed point around which it moves. This unmoving body should then be made of stuff that differs from the heavenly stuff. Indeed, the immobility of the central body or Earth is explained by the fact that the stuff which it is mostly made of – earth – moves naturally towards the centre of the universe: earth moves only when it is forcefully taken away from the center, and when it arrives at the centre, it stops moving.

The Earth differs then from stars and planets, because it allows the movement of bodies to stop. Indeed, the movements of earthly bodies seem to be of many different kinds. Aristotle now believed that this multiplicity of motions could be analysed through the motions of some simple sorts of stuff, which would then form the primary division of bodies in the centre of the universe. He also suggested that we should assume only a small number of such sorts of stuff or elements. Especially one should not think that there are infinitely many elements: the elements are to be differentiated by their characteristics, but there is only a limited number of elementary characteristics. Then again, one element is not sufficiecnt for explaining the existence of all the various phenomena in the world. Thus, we should choose a limited number of basic elements that would be differentiated by different characteristics.

We have already seen how Aristotle needs at least one sort of earthly stuff that moves towards the centre of the universe. Then again, he also points out that some things appear to move away from the centre, particularly fire that always move upwards. Between these two stuffs, earth moving always downwards and fire moving always upwards, there appears to be a stuff moving upwards, except when fire stops it – the air – and a stuff moving always downwards, except when earth stops it – water.

Aristotle also describes the relation of the four earthly stuffs or elements in terms of what he describes as basic qualities. The elements can be classified, firstly, according to the capacities of action that they have. Some things are hot, that is, they separate mixed combinations into their constituents and generally activate natural processes inherent in other things. This quality of ”hotness” appears to be associated with the upward movement: air and especially fire are hot. The opposite quality of ”coolness” – the capacity for combining various consituents and generally of hindering natural processes – is then linked to the downward movement of earth and water.

Aristotle also notes a second way to classify elements according to their capacities of receiving effects from other things. The extreme elements or fire and especially earth are dry in the sense that they have a definite shape, but are not easily malleable, while the mediating elements of air and water are moist in the sense that they have no definite shape, but are easily malleable.

Other qualities of elements and of their combinations should then be definable in terms of the four basic qualities. Thus, in a solid object the quality of dryness preponderates and similarly in a liquid object the quality of moistness preponderates.

It is the four primary qualities that actually define the basic elements, and what are usually called earth, water, air and fire are in fact only states of these elements. Particularly the hot and dry element is not always flaming, but could exist as a sort of dry gas, although it is the one most easily flammable: the meteors and comets Aristotle interprets as such inflammations of the hot and dry element.

Aristotle noted that the four earthly elements he had described do appear to change into one another: e.g. when water is applied to fire, a piece of earth is left behind, and when water is heated by fire, vapour or air is generated. In addition to such transformation, the elements can combine and so form more complex entities. The change of earthly things is thus accepted by Aristotle, but what originally instigated such changes? Aristotle's answer is that the earthly changes must eventually be caused by the movement of the heavens and particularly the closest spheres carrying the Sun and the Moon around the Earth.

By themselves, the four elements would in time move into their corresponding layers and remain stable for eternity. The movement of the spheres mixes the different layers, which thus form more like a continuum of different combinations of elements. For instance, atmosphere is formed of both dry and hot or ”fiery” element and moist and hot or ”aerious” element. When the dry air preponderates, the weather is windy, but when the moist air preponderates, clouds are formed and it begins to rain. Sometimes dry gas gets trapped in a cloud, and when it is released, it creates a loud noise called thunder and perhaps bursts into a flame called lightning. Similarly, earthquakes and volcanoes are explained by the dry gas being trapped within the Earth's crust.

The combination of the four basic elements produces then various natural substances. Aristotle never managed to give a detailed classification of all such combinations, but his examples suggest that the analysis of particular substances would have been based on the qualities of the substances in question. Thus, compounds of earth and water with earth in a predominating magnitude are dry and so become solid when heated, while compounds with water in predominating magnitude become solid when frozen. Neither of these things happens to olive oil, so Aristotle concludes that it is actually a combination of air and water.

The combination of elements leads first to substances that do not appear to consist of smaller parts, when the elements mix completely with one another. From such substances then more complex material structures are formed. The most intriguing composed things are undoubtedly living things, and indeed, Aristotle and his followers did spend much time in observing the compositions and behaviours of various plants and animals, thus beginning the sciences of botany and zoology. Aristotle even suggested some preliminary classifications of living things, for instance, he suggested that living things formed a hierarchy from less to more perfect. Yet, he offerred no complete classification and he was definitely against any a priori division of living things: one could not e.g. start in the Platonian manner from a notion of living being and by a constant division into two parts reach all the individual species.

Yet, even after observation and classification of living beings, it still remains uncertain what being alive actually means: what makes certain complex entities e.g. move about on their own accord? Aristotle did not believe that such liveliness would be caused by a separate element – material or immaterial – that could be used to fill bodies, like soup fills a bowl. Liveliness is not also, says Aristotle, identifiable with a single, harmonious state where elements would be mingled with one another in a certain proportion. In fact, the body would, according to this theory, stop being alive at once whenever a human being would fail to find this harmony.

Liveliness is then to be found in a process of living that structurises the passive materials into a living being. What is important in a living being is then the structure that the individual process of living tries to actualise. The materials used might be important in a secondary sense, namely, if the process of life requires certain type of material: for instance, if a living being creates a hard shell around its innards, it can use only hard enough substances for this purpose.

A living being, like a plant, has then a capacity to do certain things, such as nourishing itself when in contact with suitable material. The nourishment enters the living being through its superior part, which in the highest creature or man points towards the most superior parts of the world, and after the living being has appropriated the material it requires, it drops out the unrequired residue. Aristotle emphasises that it is the process of life that is active in the act of nourishment, while the nourishing material is just a means for rejuvenating the passive materials constituting the living entity.

Aristotle also connects the structure of life with his theory of material elements and basic physical qualities. Because heat means the capacity to activate natural processes, living beings as active must be warm rather than cold. But similarly living beings must be moist, because dry objects do not easily change their state, whereas living beings must do this. Thus, a living being must remain warm and moist, and a living entity which fails to retain its natural moistness and which secretes lot of liquid will probably not live very long.

The source of the heat activating the processes of life can then be regarded as the primary source of life. This source resides in the centre of the living thing, for instance, in the heart of a human being. The heat in animals together with their intestines reshapes the food in a form capable of nourishment (the plants do not require such reshaping, because they receive their nourishment in a form directly enjoyable). The final form of the nourishment in the more perfect animals is blood, which is by itself a cold substance, but as animated, acquires heat and then feeds and activates the whole body.

Although heat is central to living, a living being cannot live on mere heat, because mere heat by itself would finally quench itself, just like fire is finally extinguished when it has burned its fuel up. Thus, a living being must also control its heat and cool it in some manner. This is especially true of blooded animals, because animated blood is quite hot. In many blooded animals this happens through respiration, which uses air to cool the body: the exception are fishes that are cooled by the surrounding water. Another source of cooling in animals, according to Aristotle, is the brain, which is supposedly made of cold elements.

Beyond nourishing themselves, most living things can also produce other living beings and thus mimic the eternal movement of stars. Note that Aristotle thinks that not all living things are capable of reproducing. Some species that mix the characteristics of both plants and animals, like starfishes, are generated spontaneously from lifeless matter: a certain type of hot air is capable of instigating a process of life, e.g. in seas where all sorts of materials required for living are to be found. The results of such spontaneous generation cannot produce any offspring themselves – or at least they produce only imperfect offspring, incapable of any further generation.

Plants, according to Aristotle, generate individually, because of their simplicity. In the higher animals generation requires two individuals. One of them – the male – can develop its blood into a form that is capable of generating new living individual, when suitable material is given. This generating agent is semen, a substance generated out of blood and resembling oil in being a foamy mix of water and the forementioned hot air, but also with the capacity of becoming a living animal with sensations and motions.

The material for the semen is provided by the female, who is inferior, says Aristotle, and cannot produce any semen by herself. Instead, the female has an abundance of blood that can be enlivened by semen: if the blood is not used for producing a new living being, it will leak out in menstruation. Just like semen has the capacity of becoming a living animal, the blood in general has the capacity to become alive. After copulation, the semen activates the life of the blood in the woman and creates the central point or the heart, around which the new animal is generated. If the semen can completely control the material it uses, the resulting animal is a male of its kind, capable of producing new semen, and resembling its father. The loss of control means that the animal generated will fall short of perfection: it might be a woman, it might resemble an individual of earlier generation, or in worse case, it might completely fail to have the structure of its own kind.

Living things are not all of the same type, but form a hierarchy according to their capacities, and thus, different animals are generated in different manners. Very cold – that is, very passive – and very dry – that is, very inflexible – animals can only produce quite imperfect offspring that still require some development outside the generating animals: the offspring might be an egg that still grows before turning into a true animal, like with fishes, or even worse, a mere larva that still requires turning into an egglike cocoon before developing into an animal, like with insects. A more active, but still inflexible animal, like bird, can produce a hard egg, which needs not grow itself before turning into an animal; on the other hand, a more flexible, but still passive animal, like shark, can produce a soft and fragile egg, which the animal can turn in its own body into an animal. Finally, both active and flexible animals, like human beings, can produce full animals on their own.

In addition to methods of generation, Aristotle suggests various ways to classify living beings. For instance, plants live through earth, while higher animal life is based on air. Living beings that share characteristics of both animals and plants live in water, which is the element situated between air and earth. Aristotle also hints that Moon might be a home to life based on the fourth element, fire.

A more important differentiating factor is the capacity of sensation. While plants can only regenarate themselves and their species, animals have also the capacity to receive affections from their environment. That is, not to be affected by material things – plants are also affected in this sense – but merely by their outward structure. For instance, through vision an animal is affected in one way by visible or coloured things, in another way by an absence of visibility or darkness and in a third way by an overabundance of visibility or brightness. Usually the senses of the animals are situated at one side called front, which is also the direction to which the animals generally move.

Aristotle thinks that all sense affections require some mediating element, for instance, visible things are mediated by light and sounds and smells by air. Touch and taste Aristotle thinks to be peculiar in that the mediating element is actually a part of the body, that is, flesh and tongue. They are also the most primary forms of sensation, because all animals must be able to feel tangible things and to taste what they are eating. The flesh and the tongue both require some protection: some animals have a hard shell encasing the soft flesh, while others have hard bones keeping the flesh together, and the tongue is hidden behind lips and teeth.

Vision, hearing and smell, on the other hand, are required only by animals capable of movement, which need to sense things from far away. Smell is of these the closest to the contact senses, and indeed, smell and taste are closely connected. Just like tastes have a role in eating, smells vigorate, but only suitably developed animals. Colours, finally, are according to Aristotle the truest form of sensation there is: while e.g. speech of a person may be distorted by the air, the sensed colours should be at least close to how the object itself is coloured. Thus, when two colours form a new colour, the objects having these colours have also been combined into one object.

While some of the affections occur only in one sense, some, such as movement, are common to many senses. Thus, in addition to colours, sight can be used for sensing that a thing moves. In addition to such common sensibles, we may sense in a more figurative way more complex things, just like we can see an anger in a person, when we interpret him to be angry because of certain expressions we literally sense. Aristotle also thinks that the general capacity of sensation reveals not just characteristics of other objects, but also characteristics of ourselves. Thus, through vision we sense not just colour of apples and plumes, but also the fact that we are currently sensing apples and plumes. Aristotle also suggest that the central capacity of sensation lies at the same place as the source of the animal life, namely, at its heart.

When the general capacity to sense is temporarily nullified – e.g. through a certain phase in digestion, Aristotle suggests – the animal enters a state of sleep. Although the sensing proper has stopped, there might still be afterimages or dreams left from the daily events. An animal might even have a better view of his own bodily condition and dream about its possible ailments, because in a dream state the normally minimal signs of sickness are amplified.

In addition to sense, some animals have a capacity for, as it were, perceiving images of things that are not there. This capacity might be a cause of delusions, but it also allows the animals to consider possible outcomes of different processes. Furthermore, this capacity makes the animal capable of remembering previous events. Developed animals could even consciously regulate what they happen to remember through different mnemonic devices.

This capacity of imagining is closely connected with the ability of an animal to move itself for the sake of something. Indeed, without the capacity to remember and ponder possibilities, the animal could not do anything purposefully. This ability to move itself or act is still not completely independent, because it is instigated by something beyond the animal, namely, the desired conclusion of the action. The animal senses or imagines that something is the case and then instantly notes how to obtain what it wants. All this should happen at the centre or the heart of the animal, and from there the impulse to change the state of the body begins. Particularly the impulse to move goes from heart to the joints that move the limbs with the aid of immovable earth. Just as nourishment differentiates between the superior and the inferior parts and sensation between the front and the back, the movement supposedly differentiates between the right and the left: animals begin the movement with their right side.

The highest capacity of a living being is reserved, according to Aristotle, to the highest form of living being, that is, humans: Aristotle even hints that this capacity is transplanted into a generated human being from a source external to the parents. Humans have the capacity to consider not just sensed characteristics, but all sorts of structures in their thinking. Thinking person is then just like a universal capacity for considering all possible things there is to consider. This capacity also gives humans more powers in their deliberation over what to do: they can reason what is truly worth a deed. Beyond this passive capacity, Aristotle suggests, there exists an activity that arouses different structures for the passive capacity to think. This activity, Aristotle thinks, is not anymore capable of change, but exists in a higher realm than mere physical world of variability.

Methodology of science

Platonic school developed no fixed theory, although all Platonists shared some basic thoughts of e.g. a source of unity and oneness beyond the sense world. But it is not Speusippos or Xenocrates who we remember of Plato's successors, but Aristotle who founded his own school of philosophy. It is often discussed whether Aristotle was some sort of rebel who turned from the Platonic world of supernatural sources or ideas to nature or whether he still was close to Plato's own teachings. The question is difficult to decide, because we have no succession of Aristotelian writings starting from his Platonic days and ending in his own matured thinking, but only writings of different issues, often even collected from different eras of Aristotle's life and mixed sometimes in a rather confused manner – worst example being the so-called Metaphysics, which shows clearly its cut-and-paste origin. Because of this, we have to revert to the pre-Platonic manner of expressing the whole of Aristotle's philosophy as a whole with no genesis: although Aristotle's views must have progressed, it is usually impossible to determine this progression.

Although Aristotle's development from Platonic positions is usually difficult to demonstrate, it is still sometimes possible to show that Aristotle answered some questions that were discussed already by Plato in his dialogues: often Aristotle preferred considering actual examples, while Plato had tried to determine answer to them through discussion and arguments. Thus, Plato had considered whether there was some natural language or whether all language was merely based on custom: in effect, Plato was concerned about the possible divide between language and what was described by language. Aristotle noted that at least Greek language did not correspond perfectly to world, because one word might have had many different meanings: this phenomenon of homonymy is familiar in almost any language.

Although homonymic words made the relation between language and things more complex, they still did not completely break the connection between the two. Indeed, Aristotle took it for granted that words were used in describing things in some manner. Yet, he quickly noted that certain groups of words played different roles in these descriptions: these roles he investigated in his work Categories. One group of words did not so much describe anything, but named it: “Socrates” did not tell anything of a thing, but only named it. Such names were connected with individuals and answered the question “who or what is it”. What's that coming down the road? Oh, it is just Socrates. Indeed, these words were a sort of basis for all descriptions: we call something black, and when we are asked what is black, we can say it is our dog Fido.

Yet, the question “what is it” can be answered in another manner also: we can say of Socrates that he is a human being and of Fido that he is a dog and of both that they are animals. Yet, these answers are always secondary in comparison with the names of the individuals, because we can respond these answers with a new question “what dog” or “which human being is it”. These generic word “animal”, “human” and “dog” formed then hierarchies where e.g. humans and dogs were all animals.

Beyond names and generic words there were words of a completely different sort. Socrates is Socrates always and he is human being and animal also always, but he has also other descriptions that are not as necessary to him. Of these more arbitrary descriptions Aristotle discerned many different sorts. Thus, Socrates could have qualities like paleness. Such qualities had often opposites (paleness vs. darkness), but not always (what would be the opposite of redness?) and one could also be e.g. more or less pale. Furthermore, he could have quantitative properties like being 170 cm tall. Such quantities did not usually have opposites (although such indeterminate quantitative terms like large and small might have) and one could not be e.g. more or less 170 cm tall. Another interesting group formed of relative words: Socrates might have been described as a father, which then implicated that someone was his son.

In a similar manner Aristotle went through different contingent descriptions, and all of them answered to a different question (e.g. where is it, when was it, what did it do, what was done to it etc.). All of these words were then single words, but Aristotle noted in his work On Interpretation that we could also put such words together into combinations. Within these combinations the words might lose their usual meaning or gain new ones. The words and their combinations might also be modified in such a manner that these modifications are not independent words or expressions, but forms of the original word or expression: “Peter's” is not a word different from “Peter”, although it expresses the notion of Peter having something that is not implied in the original word. Furthermore, words and expressions might be combined with a negative: “not-man” or “not-blue”. These negative combinations are peculiar, because they do not refer to any object or property of an object, but to a lack of something.

An interesting differentiating characteristic is whether the expression in question has a reference to time. Expressions like “sheep”, “red bicycle” or “gas station near Alabama” do not refer to any particular moment of time. Then again, expressions like “is a vehicle”, “had a nap” and “will be going to have a terrible headache” all refer to some point in time, whether it be past, present or future. Although the examples of the previous paragraph were of expressions with no reference to time, the expressions referring to time can also be inflected and modified by negations: some examples are “wearing a ring” and “is not dark”.

Out of these expressions more complex could be constructed, such as prayers (“please give me that horse”) or questions (“what is the quickest route to Paris”). Aristotle noticed that some combinations had a characteristic that single words did not have, namely they could be called either true or false: an expression was true, if what it expressed was so, and it was false, if what it expressed was not so. Simplest of such expressions or statements consisted of two parts, one of which did not refer to time, while the other referred: e.g. “young sheep is in the field”, which consists of expressions “white sheep” and “is in the field”. Although the simple statement itself could be called true or false, neither of its parts could: neither “white sheep” or “is in the field” is either true or false. Simple statements could then be combined into a more complex statement using words like “and”: e.g. “I went shopping and I met my mother”.

Aristotle goes on to classify various sorts of simple statements. In some cases a statement says that something is the case – these are affirmations – while other statements use negatives to deny something – these are called negations. Aristotle notes that if an affirmation and negation speak of the same thing, one affirming something that the other denies, the two statements cannot be true at the same time or in the same sense: if “I am in Paris” is a true statement, then “I am not in Paris” must be false. Such a pair of affirmation and negation is called a pair of contradictories. If affirmation and negation appear then to be true at the same time, Aristotle concludes, they cannot speak of the same thing or they are not contradictories.

Statements might designate the things they speak of by using words designating certain individuals or names – “Fido is a dog” – or they could use words referring to kinds of individuals – e.g. “dog was playing with a ball”. The latter sort of statements use generic words, but they still speak of individuals. Yet, unlike the statements using names of individuals, these statements do not speak of any determinate individual: thus, statements like “man is riding a bike” and “man is not riding a bike” might well be true at the same time, if they just don't speak of the same person.

Further classes of statements can be found by using instead of words their negatives: thus, we could say “not-man is white”, where we would speak not of a thing of a definite kind, but of an indefinite thing, which happens not to be a man; or we could say “man is not-white”, where we would not say anything definite of the man in case, but only pointed out his lack of whiteness – furthermore, both of these new statements might again be negated by saying either “not-man is not white” or “man is not not-white” or combined together into an affirmation “not-man is not-white” or negation “not-man is not not-white”.

Although generic terms can be used in referring to individuals, they can also be used in referring to all members or a kind or to a portion of that kind by using words like “every” and “some”. Hence, we could affirm “every sheep is white” or deny this by saying “not every sheep is white” or “some sheep are not white”. Similarly, we could affirm “some sheep are white” or deny this by saying “no sheep is white”. The two pairs of statements discussed in the previous sentences were contradictories: one denied what other had affirmed. Yet, in a sense the sentences “every sheep is white” and “no sheep is white” are also opposed: only one of them can be true. Still, there is a room for a third option, namely, that some sheep are white and some not. Thus, the two statements are not to be called contradictories, but contraries.

Two contradictory statements or affirmation and its negation cannot be true at the same time. Aristotle notes that one might demand a justification for this presupposition, but continues immediately that in this case no strict deduction cannot be given, because all arguments are usually based on this rule: indeed, the whole point about arguing about truth of some statements is the belief that all statements cannot be true. Still, Aristotle gives a sort of practical justification: if affirmation and its negation could be true at the same time, one might as well throw himself down the cliff, because after that it might also be true that he had not thrown himself down a cliff.

It seems then reasonable to suppose that affirmation and its negation cannot be true at the same time. In most cases it seems also that at least one of them must be true: either today is Monday or it is not or either I was here yesterday or then I wasn't. But when the affirmation and negation discuss about future events, it seems plausible to suppose that neither of them might yet be true: otherwise, it would already be determined that tomorrow it will rain or that tomorrow it will not rain, although it might be that it is up to chance whether tomorrow it will rain or not.

A further interesting modifications of statements occur when we describe some statements as necessary, possible, impossible, contingent or true. Here appear certain grammatical difficulties involving contradictories. If we think of a statement beginning with “it might be that” followed by some affirmation as involving possibility, then it might seem obvious that a contradictory of such statement would be stating the possibility of some negation. Yet, it can well be that e.g. I might be swimming and I might not be swimming: possibility of affirmation does not preclude the possibility of negation. Instead, the true contradictory would be the denial of possibility: I cannot swim. Similar considerations apply also to other terms like possibility.

Aristotle noted that these concepts have rather interesting relations to one another. For instance, if something is possible, it cannot be impossible and vice versa. A difficult problem is the relation between necessity and possibility, because the word “possibility” is actually used in an ambiguous manner. Sometimes we say “it may be so” and immediately conclude that “it may also not be so”: in this case what is possible cannot obviously be necessary. Then again we also say things like “fire might burn”, although we would not accept the conclusion “fire might also not burn”. In other words, we have two different ways to use words indicating possibility: either they indicate that something is merely possible, but not necessary or then they indicate that something is possible and perhaps also necessary. In any case, we seem to have three levels of possible matters. Firstly, things might be necessary, just like fire can hurt, because it will of necessity hurt when you touch it. Secondly, things might be possible and sometimes even true or actualised, just like I might be walking downtown, because I sometimes do. Finally, things might be possible, although they have never been and might never be actualised, just like a woman might conceivably be a pope, although no woman has ever been one.

Aristotle did not just analyse various sorts of statements, but noted that when some statements were known to be true, we could immediately conclude some other sentences to be true also: these relations between statements he considered in his Prior Analytics. In very simple cases we could assert a new statement just on basis of one statement by converting the order of the terms in the statement. Thus, if no wolves are lions, then clearly also no lions are wolves. Similarly, if some white animals are humans then some humans must be white animals. Then again, if all humans are animals then not all, but some animals must be humans.

A more complex conclusions involve then at least two statements called premises, from which a third statement is deduced to be true: such deductions or syllogisms involve then three terms, two of which are somehow connected in the conclusion. The third term can then be related to the other two in three manners: if the three terms are A, B and C, and we want to connect A and C, B might be feature of one, while the other is feature of B (e.g. A is B and B is C), B might be feature of both A and C, or finally, A and C might be both features of B. Thus, we get the so-called three figures of syllogism.

In syllogism of each type the premises could both have one of the many shapes a statement is known to have: they might be universal (“All As are Bs”) or particular (“Some As are Bs), affirmative (“As are Bs”) or negative (“As are not Bs”). Now, Aristotle went painstakingly through all the possible combinations of different types of premises in each figure and pointed out which combinations occasioned valid deductions: that is, from which type of premises we could without a doubt conclude something. In some cases the validity of deduction could be seen immediately: if all As are Bs and all Bs are Cs, then clearly all As are Cs. In some cases a syllogism needed to be proven through syllogisms known already to be true: for instance, if a) no C is B, but b) all As are Bs, then we know that no B is C and thus can conclude through previously known deductions that c) no As are Cs – so we can conclude statement c) from statements a) and b). In other cases such straightforward proof is not possible, but Aristotle shows that if some conclusion would not follow from certain statements, then some contradictions would occur. For instance, if a) all Bs are As and 2) some Bs are not Cs, then 3) some As are not C: otherwise, all As would be Cs, but because all Bs are As, all Bs would also be Cs, which was not the case.

If Aristotle would have just enumerated valid syllogisms, we would still be unsure whether the rest of the possible syllogisms would contain some valid syllogisms. Therefore Aristotle showed carefully that other combinations of premises did not lead to any conclusions. His method was to show two different examples where in both premises of certain types hold, but the possible conclusion was different. For instance, no swan or crow is horse (no As are Bs) and some horses are white (some Bs are Cs): still, no conclusion can be made, because in some cases some As are Cs (some swans are white), while in other cases no As are Cs (no crow is white).

The syllogisms Aristotle studied were thus classified according to three criteria: according to the relations of the terms, according to whether they were universal or particular and according to whether they were affirmative or negative. He also attempted to investigate what an addition of a fourth sort of classification of statements would do: that is, the classification of statements as possible, true or necessary. Here the complexity of the task apparently overwhelmed Aristotle. He accepted some dubious principles. For instance, he believed that a syllogism needed only one necessary premise for a necessary conclusion: hence, if I happen to have a triangular door, then because triangles have necessarily three angles, my door would necessarily have three angles – although a door could well have four angles also. Furthermore, Aristotle noted properly that possibility could have several meanings – “it is possibly so and so” could mean either “it is possible, but not necessary that something is case” or “it is possible and perhaps even necessary that so and so is case – and then just confused these two different interpretations whenever possible.

Although Aristotle's dealing with possible and necessary syllogisms was not a success, at least his investigation with ordinary syllogisms was. Indeed, he did more than merely pointed out the valid syllogisms. For instance, he made several interesting observations on the different types of syllogisms. He noticed that through second figure – syllogism of the sort “A is or is not B, C is or is not B, thus A is or is not C” - one could only achieve negative results, while through third figure – syllogism of the sort “B is or is not A, B is or is not C, thus A is or is not C” - one could achieve only particular results. From this he could at once see that universal positive statements were particularly hard to deduce: in fact, there was only one valid sort of argument leading to universal positive conclusions, namely, of the type “all As are Bs, all Bs are Cs, thus, all As are Cs”. On the other hand, such statements were particularly easy to refute.

Aristotle also described how one could generally reduce syllogisms to other syllogisms, that is, how one could deduce these syllogisms through other syllogisms. Particularly he showed that syllogisms of other figures could be reduced to syllogisms of first figure, while all the syllogisms in this figure could be reduced to the only syllogism having a universal positive result – which in turn was not reducible to other syllogisms. This incontrovertibility of reduction underlines the importance of the syllogism for deducing universal positive statements: other syllogisms can be based on this statement, but not the other way around,

No Greek philosopher before Aristotle had discovered such a method for establishing true statements and only few had even considered the problematic. The only true predecessor of Aristotelian syllogistic was the method of division in the Platonic school, and Aristotle shows considerable effort in showing that his method beats Plato's. The method of division started from a known fact of the type “A is B”, e.g. humans are alive, and from another known fact of the type “B is either C or D”, e.g. living things are either plants or animals. From these premises one can only conclude that As are either Cs or Ds (humans are either plants or animals), but not yet that As would be, for instance, Cs: this can only be established by a proper syllogism, Aristotle says.

What is so revolutionary in Aristotelian syllogisms is that if they are applied to true premises, they invariably produce true conclusions. On the other hand, syllogisms might result in true conclusions even if they start from false premises. Thus, if one thinks falsely that all crows are horses and that all horses are black, one can still deduce the true conclusion that all crows are black: here the conclusion is correct, but it has been justified through incorrect reasons. Because sometimes false premises lead also to false conclusions, we can be certain of the truth of the conclusion only if we are certain of the truth of the premises.

Aristotle actually tries to show that all proper deductions or arguments producing truths from known truths are syllogisms or consist of syllogisms or at least use syllogisms without being syllogisms. Sometimes a deduction seems to be more complex than a syllogism, but then can be analysed into a series of syllogisms. At other times deduction or its part is based on showing that some absurdity arises from certain assumption and then discarding this assumption: yet, even here the deduction of this absurdity from the assumption requires some syllogisms. Aristotle even gives some instructions how to turn arguments into syllogistic form: the important thing is to find a term that repeats itself in various statements, because this is usually the middle term connecting other terms. This method of turning apparent arguments to syllogisms might even be used in evaluating whether an argument is valid or not, Aristotle surmised. Aristotle shares some hints as to how to pick out the terms for syllogisms. He also notes that although statements like “A is B” are the main area of application, other types of statement can also be used in syllogisms: for instance, if cows are animals and cows like to go into field every day, then some animals like to go into field every day.

Aristotle did not just satisfy himself with theoretical investigation of syllogisms, but he also gave practical advice on how to find syllogisms: something that often was forgotten after him. One wants to prove that A is B or that A is not B: what is one to do? Firstly, one should consider not contingent features of an individual A or B, but features of every A and B. Then one is to consider what one can deduce from something being A or B: whether As are Cs, whether Bs are not Ds etc. In addition, one is to consider which things are known to be As and Bs: e.g. whether Es are As etc. From all these considerations one should then try to discover some common elements that could be used in connecting A and B to one another: e.g. if all Fs are both As and Bs, one can instantly deduce that some As are Bs and vice versa.

Aristotle came from Platonic tradition where dialectical conversations and debates were thought to be the correct way of practising philosophy. It is therefore quite understandable that Aristotle wanted to show his syllogistic to be a good tool for such debates. Hence, Aristotle gave also instructions for construction of new syllogisms from known syllogisms: for instance, if we know how to justify some statement through some premises, we might be able to justify the premises through syllogisms, and if we know a possible justification of a conclusion, we can produce an appropriate syllogism for refuting that conclusion. Here it is clearly not important to find the true conclusion, but to beat the opponent in cleverness. This is even more apparent in Aristotle's instructions how to make syllogisms by using opposed terms, that is, how to deduce evidently false conclusions when someone accepts e.g. both that science is good and that science is bad; or in his instructions that we can justifiably object when someone tries to refute a statement with a syllogism ending up with a contradiction, when the statement itself has not been used in the syllogism as a premise.

Aristotle also considered a number of other , not as reliable forms of justifying statements that might also occur in a Platonic debate. Thus, if we know from a number of different types of objects that they have some feature (e.g. lions are mortal, humans are mortal, pigeons are mortal etc.) and we know that these types are all species of a certain genus (e.g. we have gone through all animals) then we can conclude that everything of this genus has this feature (all animals are mortal). Furthermore, if we know one example where thing of a certain kind has some feature, we can use this example as a sort of paradigm or exemplary case by which we can assume that other thing of the same kind probably has the same feature: if I know that Greece lost the football match against Serbia last year, I might assume that they lose it this year also. Finally, we can use features that are commonly associated with a thing or event of some sort as signs of thing or event being of this sort: that is, if we know that pregnancy causes female breasts to produce milk, we may reasonably conjecture that a woman with breasts producing milk is pregnant. All these modes of justification fall short of the trustworthiness of syllogism, even if they start from true premises, but they might come handy in Platonic debates.

The Platonic method of dialectical debates was obviously important for Aristotle: such dialectics practised intellectual capacities. Aristotle thus produced a whole treatise called Topics on how to gain dialectical skills. In a dialectical debate a proponent tries to make her opponent accept some conclusion. She can base such conclusions on previous propositions she can make her opponent accept. Therefore, the dialectician should know what propositions are accepted generally or at least by eminent persons who are held to be wise: the opponent is more likely to accept such propositions also. Furthermore, the debater should be aware of the meanings of words so that she cannot be deceived by e.g. using a name with different meanings: in best case, she may able to deceive her opponent. A knowledge of structural similarities is also helpful, if the debater wants to base her conclusion on analogies.

The Topics is full of rules of thumb for showing that an object has or does not have certain accidental characteristics – if thing has a capacity for one characteristic it must have a capacity for its contrary (if people can know things, they can also be ignorant), and if something has naturally a quality then they have this quality in a greater degree than something that doesn't have it naturally (berries taste sweeter than sweetened food) – that an object belongs or does not belong to a species – if a thing belongs to no subspecies of a species, it does not belong to the species either (if a creature does not belong to any species of animals, it is not an animal) – that a property either inclusively and necessarily characterises an object or not – if a lack of a property does not characterise a lack of an object in this manner, then the respective property does not characterise the respective object in this manner (deafness does not entail lack of sensation, thus, hearing is not the only sensation there is) – and that an object is or is not defined in a certain manner – if the supposed definition can be more intensive, while the defined thing isn't, the thing hasn't been defined correctly (because a desire to have sex with a person can become more intense, while the love towards that same person can remain at constant level, desire to have sex does not define love). Aristotle also notes that it is most difficult to show that something is the definition of an object, a little less difficult is to show that a property belongs to an object inclusively and necessarily, easier to show that an object belongs to a species and easiest to show that an object has an accidental characteristic: the difficulty levels of disproving these are opposite.

Aristotle, gave also a more normative instructions as to how a good dialectician asks his questions and how a good opponent answers them: both should be skilful, .but fair contestants. Thus, the answerer must accept those propositions that are widely accepted and that are not relevant to the question in case, but refuse to accept propositions that are not widely accepted or that would instantly lead to the questioner's victory: on the other hand, he must accept the seemingly absurd consequences that follow from the thesis he is upholding. Similarly, the questioner should approach his goal in a covert manner, but still avoid some obvious fallacious forms of reasoning. Aristotle even presents a number of such fallacies in another work, Sophistic refutations. These fallacies could be used in more aggressive debates, meant to embarrass the opponent, and one should learn both to use them and to answer them. Still, the Platonic debate should in its proper form not be used for such a contest, but for educational and research purposes.

But the true worth of syllogisms lies not in their use in such debates, according to Aristotle, but in their capacity to lead to true conclusions from true premises: this is what Aristotle's Posterior Analytics investigates. Thus, if we already know something without a doubt, we can use syllogisms to gain further knowledge. In this case syllogisms can be called demonstrations, which provide us with incontrovertible knowledge of facts and also some bases on which to justify and explain these facts. The presupposition of such demonstration is that we start from premises that are more certain than the demonstrated conclusions and that can be used to explain these conclusions.

Aristotle was convinced that demonstrations were truly possible. Indeed, he could always note that the mathematicians of his time had discovered some real demonstrations: for instance, they had shown that the sum of all angles of a triangle was always equal to sum of two right angles Now, if all statements required some justification from statements known to be true, demonstrating couldn't really begin anywhere: hence, Aristotle was committed to the idea that demonstration was not the only source of knowledge. Aristotle tried even to show directly that infinite chains of justification would be impossible. A chain of demonstrations must begin at least from some final thing of which we can say something, but which cannot be feature of anything, that is, from individuals and their immediate classes. Similarly, a chain of demonstration must end at least with some features that cannot be described any further, that is, the ultimate classes, like substances and qualities. The only other option beyond infinite and finite chains of demonstration would have been to endorse the possibility of circular demonstrations where conclusions are first based on premises and premises then on the original conclusions. Such a circularity would destroy the essential difference between basic and applied knowledge and would also lead to a mere moving in familiar circles without any novelty being reached, therefore, it was not to be accepted. True knowledge should thus be based on some indubitable premises from which all the rest of the truths should be deduced through demonstrations.

The final premises of such a string of demonstrations should confirm to some criteria. These premises should describe properties of all members of some class of objects. Furthermore, these properties should be either essential to these objects – although all men would have crooked noses, this would not still be essential to them being men – or they would have to form an essential division of the class of objects – just like all numbers are either odd or even. Finally, the premises should deal only with the highest possible classes having certain properties: that is, a statement “right-angled triangle has three sides and three angles” would not be a final premise, because we could demonstrate this statement from further premises like “triangle has three sides and angles” and “right-angled triangle is a triangle”. This final demand for the premises is actually applicable also to demonstrated knowledge: it is better to demonstrate that the sum of angles in all triangles equals two right angles than to demonstrate this just for right-angled triangles. Because the premises of a proper demonstration should be necessary and essential and the demonstrations should also produce necessary and essential knowledge, we could never demonstrate anything inessential, Aristotle says: for instance, we could not truly demonstrate that a person has a crooked nose, because he might as well have a straight nose.

Proper demonstrations should then begin from premises describing essential characteristics of certain kinds of entities. Therefore, Aristotle suggests, we should be able to divide demonstrations into different sciences which all concern some peculiar kind of entities. Thus, we get a sort of hierarchy of sciences where a science higher in hierarchy turns into a science of lower level, when some new premises are added to it. Aristotle goes even so far as to suggest that results of one science cannot be used in another science, if neither investigates subspecies of the issue of the other science: after all, they investigate completely separate kinds of objects. In cases where such application apparently happens – like when we use arithmetical calculations in geometry – it is actually a case of us using results of higher science which contains the two sciences as its possible applications. Indeed, all sciences use some common principles, like the fact that same thing cannot at the same time and in the same sense be and not be characterised by the same feature. Still, every science has its own proper problems, and problems of one science can be answered only through the premises and assumptions of this science: thus, we cannot expect a mathematician to have an answer to a medical problem. Still, one might be able to use higher science explain some facts that are taken as mere given facts by a lower science: e.g. mathematics might explain some optical phenomenon.

The special status of the first figure of syllogism is even strengthened when we are talking of demonstrations. First figure was the only means by which all sorts of statements could be justified, and particularly it is the only figure through which universal affirmative statements could be justified. Because statements concerning essential characteristics of some sort of objects are obviously universal and affirmative, Aristotle concluded that first figure was of the utmost importance in scientific considerations. In addition to being the correct source of true statements, in general, demonstrations of universal statements are more important than demonstrations of particular statements, because universal statements potentially contain particular statements: if I know that all triangles have three angles then I know this of any individual triangle I happen to come in contact with. Similarly affirmative statements are more important than negative, because all syllogisms require some affirmative premises, and therefore it is also better to prove statements straightforwardly and not through showing their contradictories to be false.

Aristotle considers also how erroneous statements or generally ignorance could arise. Some errors arise through syllogisms using false premises, and some errors arise because we do not have the necessary means by which to find the correct premises, for instance, because our sense perceptions are faulty (if we cannot see colours correctly, our beliefs about colours might be erroneous).Still, mere individual perceptions cannot make a science: we cannot know necessarily that all triangles have angles sum of which equals two right angles just by looking at individual triangles. At most sense perception will lead us to have uncertain opinions, which we might assume to be true, but which we think might also be otherwise (e.g. I might see that Rufus has a beard, but I still cannot infallibly demonstrate that he has a beard). We can, undoubtedly, use such opinions as premises in syllogisms, but these syllogisms won't be true demonstrations, because the opinions do not describe the essence of any object.

Science according to Aristotle is not described merely by its method, but also by the problems it tries to solve and questions it tries to ask. One sort of question science considers is of the form “is this such and such”, e.g. “do triangles have angles sum of which equals to two right angles”. These questions are answered by finding a demonstration where the questioned fact is proven or disproven from known facts. A bit different, though clearly related form of question says “is there such and such”, e.g. “are there triangles”. These questions of existence should also be answered by finding a demonstration where the existence of such objects is either proven or disproven from known facts.

Now, the two questions could also be turned over. Instead of asking whether triangles exist or whether they have such and such angles, we may ask why there are triangles and why they have such and such angles. Aristotle notes that such questions can be understood in four different senses. Firstly, they may be thought as asking for conditions of something: what does it require to make a triangle or an angle of a triangle? Secondly, they might be understood as asking for the thing or person accountable for the existence of this particular object: who or what has drawn this triangle with its angles? Thirdly, we might think these questions as asking for the purpose of something: what use could a triangle and its angles be? Aristotle suggests that the most important question is the fourth of the essence of things: what triangles and their angles are or what is their essence. The fourth question in a sense contains all the others within it: by knowing in what conditions triangles exist and in what conditions they have certain properties, who makes them and for what purposes, we know what it means to be a triangle.

Facts can be known through demonstrations, but essences of sorts of objects are defined: triangle is such and such an object. Now, Aristotle tries to show that definition is a method differing from demonstration. Indeed, demonstrations can reveal that something is not the case, while definitions always say that something is the case: “triangle is not square” does not define anything. Furthermore, definitions should provide the indemonstrable starting points for the demonstrations. In fact, demonstrations and definitions have completely separate tasks: definitions reveal what it means to be something, while demonstrations presuppose such meanings and then show what other properties such an object must have. Still, demonstrations can in a sense reveal the essence of something: when we know some fact, like that an earth quake is occurring, we can explain this fact through a demonstration based on a definition of earth quake (earth certainly quaked today, because the events corresponded with the essential features of an earth quake).

How does one then make definitions? Aristotle suggests the method of collecting properties that the definable species shares with some other species of same genus, because some set of such properties should characterise the species and nothing but the species: thus, number three can be defined by being an odd prime number (seven is also) which is not a sum of numbers larger than one (like two). Aristotle also suggests that the Platonic method of division helps to constitute definitions. True, divisions do not prove definitions – divisions do not prove anything, as we have seen – but they do help to classify all essences in a systematic manner: through a properly effected division we can define a whole classification of kinds of objects. Aristotle advises to begin definitions from the lowest species of objects (such as triangles) and working one's way slowly upwards to genera containing that species (like figure), because mistakes are made more often in defining higher genera.

Aristotelian science contains then a series of demonstrations based on definitions and other principles or axioms. We have seen how to find definitions, but what leads us to axioms? Aristotle suggests the following scenario. Human beings begin their quest for knowledge from sensations they receive from objects around them: this characteristic they share with all animals. In humans, and in all higher animals, Aristotle would probably admit, individual perceptions leave traces within human being, so that she can later recognise perceptions similar to those she has had before. This capacity of recognition or memory enables human beings then to make generalisations: e.g. when we see that triangles always have three sides, we at once understand that all triangles have three sides. The capacity of generalisation or “understanding” should be the property solely of rational beings, just like the capacity of systematic demonstration. Unlike demonstration, understanding should not be based on any proofs: we “instantaneously” or without any mediation see some general truth instantiated in particular events. On this immediately certain ground is based the edifice of the Aristotelian science.

Aristotelian view of science betrays its Platonic origins: indeed, we might say that Aristotle has merely purged Plato's methodology from its mythological elements. A person is brought to the firm starting point by showing her how general structures are embodied in particular instances: this is undoubtedly where Aristotle imagines the aforementioned dialectics is practised. The outcome of this practice is intuitive clarity on the essential structures of all types of things, from which then certain conclusions can be deduced. This picture of science is based not only on Plato, but also on contemporary mathematics, which indeed was the science most respected by the Greek and in which particular truths were seemingly based on intuitively clear and certain axioms and definitions: we shall see later how this mathematical ideal of science limited the understanding of other, more empirical sciences.

Ideas reconsidered

In the previous text we saw how Plato developed his mature views on ideas and on the ideal life of human beings. Yet, Plato's views were not fixed for eternity, because he found later on reasons for re-evaluating some central tenets of his work. These novel lines of thought required also a change in the form of presenting them, Plato seems to have thought. Thus, the central character and the hero of earlier dialogues, Socrates, hides often into a background in the later dialogues and sometimes even loses a battle of wits: a subtle hint of Plato's that he did not ascribe to all of the beliefs he used to have.

One obvious change in Plato's later thought is a growing concern for justifying that his methods truly resulted in knowledge. In many of the earlier dialogues Socrates tried to discover definition for some general concepts like courage or justice. A mere example of courage did not suffice for a proper definition, because such examples revealed not all possible instances of courage: only by knowing a definition of courage did one gain a capacity to truly recognise courage in all possible cases. Now, one particular concept Plato had not tackled was knowledge itself. Socrates in his dialogues had perhaps claimed to have particular instances of knowledge in his possession, but one could ask how Plato could justify that these were true cases of knowledge, if he did not even know what it required to know something

Knowing definition of knowledge was thus important for justifying the possibility to complete Plato's agenda. It is then no wonder that in dialogue Theatetus we find Socrates considering pros and cons of various definitions of knowledge. The first assumption Plato suggests is that we know something when we see, hear or in general perceive it: indeed, seeing, hearing etc. seem to be our main sources of information. Now, the problem in this definition is that people can have different perceptions of same things: wind that feels cold to one man might be warm according to another man. Thus, if we accepted perception as the criterion of knowledge, then everyone would have their own criterion of knowledge and indeed would be always correct in everything: this is the sort of relativism that some sophists endorsed. Then nothing would have any stable essence, but things would change from one context and observer to another: what is cold for me might as well be hot for you.

It is expected that Plato did not accept this definition. This definition would make opinions of every person equally valuable and would thus undermine the possibility of there being experts who knew more of some issue than others. Furthermore, the whole idea of everything changing according to the context would quickly destroy all stability from the world: we couldn't even say that different persons perceived same things in different manners, because the assumption of same things underlying different observations would be too substantial. Finally, this definition does not even correspond to the common manner of using the word ”knowledge”: otherwise I would lose knowledge of a thing at once when I stopped looking at it.

The next definition Plato proposes supposes that knowledge is something stored in our mind in form of images: experience of things leaves traces in our mind, like impressions in a piece of wax or like birds flying in aviary. This suggestion would make it possible to use knowledge of a thing even when we did not perceive it: we would just have to drag it from our memory. The trouble is how to account for occasions when we have false beliefs: we might have false thoughts flying in our head in addition to true thoughts. The problem is actually solved in a later dialogue Sophist, where Plato has noticed that our mind does not store just images, but also opinions in the form of statements. Statements always speak of something – this something is usually designated by a noun – and they say something of this issue - in verbs and adjectives. Such statements can then be obviously wrong: we could have said something of an issue, although the issue should not be characterised in that manner.

Although the problem of false opinions would have been solved thus, the idea of mere true opinions as knowledge would not be sufficient. Even a clever rhetorician could put thoughts and even correct thoughts in our head, but even after listening to her we wouldn't necessarily have true knowledge instead of mere opinions.

Knowledge is thus not completely characterised by being a true belief: something more must be added to the definition. Plato considers several emendations without finding a suitable answer. Clearly a mere ability to state one's thoughts verbally does not yet make them knowledge, because we can as well state mere opinions. A plausible suggestion according to Plato is that knowledge requires a capacity to tell what a thing consists of: e.g. we know a machine, when we can tell how it has been constructed. More generally we know something when we can define it, that is, when we can explain it through simpler terms: e.g. triangle is a figure consisting of three straight lines. The problem is that we couldn't then know anything of the final pieces of analysis, because they wouldn't consist of anything: knowledge would be based on unknowledge. Plato finally suggests that perhaps a mere capacity to recognise something would be sufficient to make our thoughts of something knowledge: indeed, we do say that we know a person, if we can recognise her among a crowd. Then again, even this suggestion seems insufficient, because we appear to need such capacity of recognition even for having thoughts: I cannot think Mark, if I can't separate him from other persons

Although Theatetus thus ends with a negative conclusion, the investigation was not in vain. It appears that at least the knowledge of complex or analysable entities involves essentially the capacity to define or analyse them. Hence, Plato suggests in his later dialogues a more systematic manner of defining things, while in earlier dialogues he had merely just tested any definitions that happened to be available. This new method works by making constant divisions: for instance, all living things are either plants or animals and humans belong to the latter kind etc. This method is still not a sure way to make correct definitions – these definitions need still to be tested – but at least it results in more correct definitions than a mere haphazard invention. Thus, in later dialogues Plato defines in this way sophist as a sort of imitator, who fakes knowledge, although he does not have actual knowledge; similarly, a statesman is defined as a sort of herdsman of humans who uses the talents of other professionals to care for the best of society. This method was clearly of great importance to Plato's pupils also. Indeed, Plato's successor, his relative Speusippus, equated knowledge of a thing with the capacity to place it in its proper place in a classification of all things: thus, knowledge of something presupposed for Speusippus a knowledge of everything.

In Theatetus Plato criticised his old enemies, the sophists, and especially Protagoras, who had insisted that anyone's opinion must be as good as any other's. In addition to sophists, Plato had now gained some new enemies, who paradoxically had been his allies against sophists. The Megaran school tried to unite Socrates' method of teaching with Parmenides' idea of the world: they tried to show through arguments that world was an unchanging unity. Unlike sophists, Megarans admitted that we could know something, and like Plato, they admitted that the true knowledge was to be found beyond what was revealed by senses. But unlike Plato, they supposed that the object of this knowledge was the unified world instead of a plurality of ideas: in eyes of Megarans these ideas would have been mere delusion as well as sensuous appearances.

Plato felt the pressure of the Megarans apparently quite overwhelming: in his dialogue Parmenides the idol of Megarans, Parmenides, is even able to dismiss the theory of ideas that young Socrates suggests to him: it might well be that the criticism of Parmenides in the dialogues originated in the Megaran school. Parmenides of the dialogue makes fun of Socrates by asking him whether such things as mud have also an ideal model. But his criticism does not limit to such cheap jokes. Parmenides questions the very relation ideas are supposed to have to the things we normally perceive. Idea of beautiful should be something that makes the beautiful things beautiful. How does it do this? Suppose the idea of beautiful is like a chemical component added to a thing to make it beautiful: then we actually don't have one idea of beautiful, but a quantity of it, divided among many things. Plato, on the other hand, upholds the idea to be a unity. Indeed, the idea of beautiful was assumed just because there were many beautiful things and some unified thing was needed to account for what makes these many things beautiful: idea of beautiful was like a model of beauty which other beautiful things resembled. Parmenides cleverly notes that one would then have to assume an unlimited number of ideas of beautiful: the first idea of beautiful together with other beautiful things form yet another plurality of beauty, which would then require yet another ideal model of beauty to account for what makes them all beautiful. Socrates of the dialogue makes the final suggestion that the ideal of beauty couldn't be compared with beautiful things, because it would be infinitely more beautiful than mere sensuous things can be. This suggestion solves the problem of infinity of ideas of beauty, but makes the assumption of the idea somewhat superfluous: the ideal beauty would then be something that god perhaps might know, but it would have nothing to do with earthly beauty, which it wouldn't even resemble.

The criticism of Parmenides makes Plato's theory of ideas suspect, but the dialogue does not stop here: Plato goes on to show that the very assumption of Parmenides and Megarans leads to equally great problems. If we suppose the existence of One – that is, of the original unified reality – we have two choices to make. The first option is to take the route of Parmenides and Megarans and avoid saying anything negative of it. Then we end up with saying nothing of it, because from every positive statement follows something negative: if we can say even that the One exists, then we can also say that it does not fail to exist. Furthermore, if we cannot say anything of the One, we cannot even say anything of its relation to the things we sense: thus, we cannot say anything of the sensuous things, because they wouldn't be even unified without some relation to the One.

The second option is to admit that we can say something of One, at least that it exists. Then we must assume that something has made it to exist or at least makes it possible for us to say that it exists. This source of existence could then be separated from One and together they would form a pair: we could then suppose another source that would make the source of being and the One into pair. Clearly we could go on finding ever new sources of triplets, quartets etc.; in fact, these sources would be Platonian ideas of numbers. The One would then be just one of the ideas, that is, it would be the source of making all unified: thus, it would make organised wholes from what we can sense and would hence allow us to speak of the world of senses.

Plato notes that these two options are actually not completely exclusive. We could also suppose that the One had been at first devoid of existence and thus beyond all discussion. Then the assumed source of being would have made the One come into being – created it, in religious terms. After this the One would have continued by making the sense world evermore unified. As this assumption supposes that One would be temporal, it would be equally tough to accept for Parmenides and Megarians.

The outcome of the Parmenides has thus far been that both Plato and Megarans have apparently been contradicted. It might thus seem that the common opponent of both – that is, sophists – would have beaten the game: there would be nothing beyond the perceptions. But at the end of the dialogue Plato points out once again that sophistic solution won't do: a sophist must also face his own dilemma. Suppose that sophist says that neither Platonic ideas nor Parmenidean One exist. Then he also has two choices. He might firstly mean that e.g. One does not exist in the perceived world, that is, that perceptions consist only of parts that do not form true wholes. Then the One would still exist beyond the perceived world: a result not satisfactory for the sophist. The other option would be that the One and the ideas would truly not exist and would even be beyond meaningful discussion. The problem is that then everything would be beyond meaningful discussion, because nothing would be unified and thus a possible subject of discussion.

Plato's battles with other philosophical schools have thus far ended with no clear resolution, but in Sophist Plato thinks that he can win both sophists and Megarans. There is not just instable motion and not just immobile stability in the world, but both: if neither would exist, there would be no possibility of thought. In other words, there is something that makes things move and something that makes things stable: these are then Platonic ideas, which are not mere components nor just ideal models, but something with the ability to make others resemble them. Furthermore, the ideas of motion and stability are not completely separate, but can mingle and affect one another. Neither of the two is a source of being and therefore a third idea is needed to make the other ideas exist. In addition to these three ideas Plato assumes then at least the ideas of similarity and dissimilarity: one is something that makes things share some characteristics, while the other separates all things. Through this new scheme Plato solves the old Parmenidian problem how one can speak of something that differs from being. Plato notes that the words being and non-being are ambiguous. There is firstly the source of being and beyond that other beings: all of them are beings or exist, but the source of being exists in a more essential manner, because without it nothing would exist. Other beings would then be non-beings in the sense that they differ from the source, although in another sense they of course exist.

The metaphysical question about the source of being was an issue that was much thought by Plato's successors. Plato was convinced that the source of being could be said to exist, and indeed, that it primarily deserved to be called existing: in any case, we could make meaningful statements of this source. Plato's successor Speusippos, on the other hand, noted that such a source would not really explain anything. That is, if a source or cause of something would just be a thing of similar sort, nothing would be explained: if you explained the existence of fishes by saying that they had came out of other fishes, you would not have explained anything, but only transferred the problem to further and further fishes. The true source of existence, according to Speusippos, should then be something beyond existence and being and therefore also beyond meaningful conversation, Thus, when Plato, for instance, says that the source of being is good or aims for some purpose, Speusippos denies this, because such descriptions as good can be used only of the existing things.

Another problematic that Plato's successors talked a lot was the relationship of this source of being to other things and especially Platonic ideas. Plato suggested a sort of hierarchy, where the source of being together with a source of multiplicity constructed first ideas or ideal models of everything, then numbers and finally other things. Now, Plato’s successor Speusippos noted that the realm of ideas would be a mere useless addition without any purpose. For instance, if we already know ordinary numbers that can be added together and separated from one another, there would be no reason to speak also of a realm of ideal and changeless numbers that could not be added etc. The successor of Speusippos, Xenocrates, tried to mediate between the two older philosophers by equating numbers with Platonic ideas: like in the ideas of so-called Pythagoreans, numbers played also the role of metaphysical forces.

If we now move on from the pure theory of ideas, we see that Plato is anxious to show how the physical world could be explained on the basis of his theory and how the findings of contemporary science could be reconciled with his own thoughts. Plato acknowledges that his account of knowledge could not admit any true science of physical world: the world is too variable to be a true object of knowledge. Yet, at least a probable account of the structure of the world could be given. Because the theory of world is of lower level than true philosophical knowledge, Plato presents this theory in a form of a mere myth or story of the birth of the world.

The physical world would by itself consist of a mere chaotic variety of ever fleeting shapes and an empty, unchanging ”place” or receptacle in which these shapes appear. The current order of the world should then come from another source that Plato calls demiurge. It is unclear whether this demiurge is a mere mythical name to some idea – to some source of order or stability – or whether it is a distinct, godlike entity shaping the chaos by using ideas as models. In any case, the true source of the stability of the world must be either immediately or mediately in the world of ideas.

The first task in the stabilisation of the world would be the shaping of chaotic mass into specific matters. Plato tells colourfully how demiurge shapes matter into triangles and then combines these triangles into four different shapes corresponding to the Empedoclean elements: earth, fire, air and water. He then continues by suggesting how other substances, like snow, oil or salt, have been produced from these four basic elements. When we abstract from the mythical aspect of the story, Plato is essentially recounting the chemistry of his own time and adding a geometrical description of its basic elements.

Plato was also interested to incorporate the astronomy of his times into his account of creation. Hence, the demiurge is told to shape the four elements into a form of a rotating ball. The newly-born cosmos is given to an entity that is formed from both the source of stability and the source of motion and so shares characteristics with both of them: this entity or psyche is what makes the cosmos into a living creature. The cosmos is then tinted with an outpouring from the source of difference – so that it does not repeat the same pattern too often – and with an outpouring from the source of sameness – so that it will finally end up in its development into its original starting position. The cosmos is then filled with bodies made of fire – the planets – that follow the rotation of the cosmos with strict mathematical rules. The planets are also endowed with psyches of their own, which correspond then to the gods of the Greek tradition.

After this stage in the creation myth, the demiurge has the chance to rest on its laurels, while the gods then get the task of creating an image of the cosmos within cosmos. Thus, they produce ball-shaped objects, to which the demiurge adds a psyche of their own – it is not clear whether these ”smaller psyches” are meant to be parts of the world psyche or independent entities. Because such balls would have difficulties in moving, the gods fashion a support for the ball or head: the body. The description of the body and its interactions with the environment follow the medicine of Plato's time. Furthermore, Plato gives a sort of mythical explanation of his theory of the three parts of human psyche. The highest or the reasoning part has already been created by the demiurge and placed in the head. Now, the gods imitate this creation of demiurge and place another psyche within human body: this psyche is then divided into two parts, one of which resides in the heart and unites lower with the higher psyche, while the other part lives in abdomen and is more concerned of the body and its wants. The two parts of the lower psyche are essentially connected with the body and die with it, while the reasoning psyche has a higher origin, according to Plato, and therefore can outlive its body. The psyches then move from one body to another, and while the first body created by the gods is supposedly male human, the womankind and animals are produced as living quarters for humans who have paid more respect to body and its wishes than to their own psyche.

Plato’s affair with natural philosophy was temporary, but his interest in human behaviour continued even in his older age. Just like he had to defend his theory of ideas against new opponents – Megarans – so did his idea of a proper human behaviour face new opponents. While earlier Plato was satisfied to show that mere pleasures without reason could not fill one’s life with meaning – after all, how could one even know how one is feeling good without reason – in his later dialogue Philebus he also goes against the idea that human beings could live a good life completely without pleasures, as Cynics had suggested. Plato agreed with Cynics, when they said that some pleasures were intrinsically related to pains – no satisfaction from food without hunger. Yet, human beings cannot be completely free of such pleasures and pains: we are no gods, we must eat to survive. Furthermore, Plato suggested that some pleasures are without pain, like the joy of seeing beautiful colours or hearing beautiful sounds. Although pleasures thus are an element of good life, Plato still thought that they were far from being the most important element: much more important is to measure pleasure in right amounts, without detriment to health of body and psyche, and this could be done only with the guidance of reason.

Plato’s theory of ideal state had to face other challenges. It had become evident to Plato in his futile attempts to educate a tyrant into a philosopher that his utopia was more difficult to actualise than he had thought. It may have occurred to him that his ideal state was completely impossible, a fantasy without any basis in reality. Plato did try to justify this ideal through another myth: he suggested that in times long gone his hometown Athens had been a Platonic state and that it had been capable of withstanding the might of a much larger empire of Atlantis. This sort of myth was not, of course, sufficient as a true proof, and so Plato was forced to consider whether there might be a more viable sort of society, which would still be better than any current state was.

An ideal Platonic state should be based on one class of people being capable of governing the whole state: a great number of guidelines is not needed by such state, because the governors should know perfectly well what the citizens truly need. A second best state, on the other hand, cannot rely on the wisdom of governors, therefore, it must at least have good laws to govern it. In other words, this state must not be a tyranny where all power has been given to one person, because such a state would be too reliant on the nature of that one person. People desire to be free, and even slaves are ruled best when they are handled fairly. On the other hand, state should not be a completely unruly democracy, where everything was decided by the irrational decisions of the crowd. Instead, the people of this state should freely subject themselves to some rules or laws guiding them. The officials who take care that people follow laws are only partly chosen by the desire of the populace and a more important element in their choice should be according to Plato a careful testing of their virtuousness: the officials should not work for gaining money and they should have no servants, but they should instead circulate in the country and live through their own means.

In a good and possible state, state officials should not then use laws for their own purposes, but should serve laws. Thus, Plato does not wish to speak of a democracy or aristocracy, but suggests that a good state is always a theocracy, because laws are supposed to be immortal like gods. Laws are still not tyrants that merely oppress people to follow them with punishments, that is, a good society is not totalitarian. Plato admits that laws cannot be decided completely beforehand and that some laws can be regulated only when people of city state have experienced what customs work best: laws might even change, although Plato thinks that this should happen rarely. Furthermore, Plato would like every law to argue for its own existence and explain why it is good to do as it suggests: for instance, a law upholding marriage and allotting fees for unmarried people would be justified by the need to continue the human race. Plato still recognises a limit beyond which law cannot anymore decree anything, even for the benefit of the people, because too much regulation in small details would be felt as too restricting and even ridiculous. Plato suggests that in these cases there could still be laws for giving merit to persons who do satisfy even those small details: such persons would then serve as examples of exceptionally praiseworthy conduct for others to emulate.

The laws are not meant to be mere external restrictions for herding the citizens, but they must also contain guides for training them to live a good life: this was also an important task of the governors in ideal state. In the ideal state it was of utmost importance to educate the wisdom of the governors-to-be, but in this second best state it is the other parts of good life that receive obviously more attention. Once again training is to be given to both sexes, because gifts of a person should not go to waste because of wrong sex. Plato notes that in many states people were educated merely for brave action in warfare through battle training, gymnastics, hunting etc. Plato also endorses such exercises that make people lose their fear of pain and train them to defend their city and suggests competitions in which people can show their skills in arts of warfare.

Yet, a mere education of courage is not enough for Plato, who wants to train citizens also to live a good life at times of peace and to be capable of battling against the lures of pleasures: he thus suggests e.g. a controlled drinking of wine as a good way to practise one’s independency from pleasures. Music is once again an important element for Plato’s idea of education of proper behaviour, and he even goes so far as to suggest that wine should be given to old men, who would thus be more eager to sing for others. All forms of music are not to be encouraged, Plato thinks, but only those that guide people best to a good life: poems, songs, dances and plays should extol the benefits of living modestly and avoiding excess pleasures. Like in skills of body, competitions are to be held in musical arts. Mathematics and astronomy is also to be taught to all citizens, although only the basics, because no awareness of the more refined aspects of them is required for everyday use.

Luxury is once again in Plato’s eyes a chief reason for ruin of states. Luxury and need for it, on the other hand, arise according to Plato from foreign trade. Hence, Plato ordains that a good state should be self-sufficient, with no need to import goods from other states, but also not too productive, so that it would not export goods in change of currency. Unlike in Plato’s ideal society, every citizen can have private property, as long as he does not become too rich or too poor. Plato also accepts the general use of money, but only such that can be used within the state: the possession of gold and silver required in foreign trade should be carefully regulated. He also sanctions trading and money lending and even suggests that these usually disrespected professions would be more respected if the traders and moneylenders would just be good men – although at the same time Plato states that no good man would ever want to take up such professions.

Plato thought that state should try to turn all necessary desires of human body into customs useful for the people and the community. Thus, the desire to eat and drink was to be made into a vehicle for making the community growing closer through the custom of shared dinners. Similarly the sex drive should be geared towards reproducing good and balanced children. Although Plato does now allow marriages, he would still want to regulate who is to marry whom: at least officials of community should try to convince persons with compatible characters to marry one another. Plato’s attitudes towards relationships between same sex appear to have become more intolerant in his later years, as he clearly says that society should condemn – if not through laws, then at least through customs – sex between people of same sex: only intercourse geared towards reproduction is commendable. Similar intolerance Plato shows towards madmen and beggars, the appearance of which if a sign of something being wrong in the society: Plato's solution is to fight the signs instead of the problems and lock madmen away from public life and banish beggars from the society.

One particular problematic occurring in the second best society, but not apparently in the best society is the need for correcting people’s behaviour: in the best society, Plato thinks, such correctives would not be needed, because everyone would act correctly and crime would not exist. Even in the second best society, Plato believes, there should be no punishments as such, because no one truly wants to do bad things. One may do bad things accidentally, like when a careless boxer strikes his opponent too hard: in such cases the damages should be repaired, but no punishment is needed. On the other hand, one may do bad thing because of ignorance or desire for pleasures: in such cases we should not punish the criminal, but to educate him, because the criminal is not in complete control of himself (to tell the truth, Plato envisioned such educative correctives to resemble what we usually call punishments). Between complete accidences and crimes of ignorance or desire lie bad deeds made because of sudden madness or loss of temper: because here the bad deed is between two extremes, the reaction to it should also be between the extremes of mere indemnity and corrective.

Plato advocates also for a state religion. Like all the commands of state, even this religion should be at first justified. Thus, the governors of the state must argue that there are entities that can regulate their own actions and that therefore are the ultimate causes for the order of the world. The governors should also explain to people that gods do care for the good of people and that their mind cannot be changed through sacrifices and other gifts. The goodness of gods is seen from the fact that they gave order to the world: Plato presents these entities or gods as battling against chaotic forces, but it is unclear whether these forces are meant as true satanic entities of whether Plato is merely using poetic language to describe unordered matter. As good and just, gods will reward good and punish wicked. Wicked people might fare apparently good and good people apparently bad, but then it is a question of mere apparent goodness and badness. Although the state religion can thus be justified, Plato also suggests that citizens who reject these dogmas must be punished for their actions: no freedom of belief is allowed, and those who cannot understand why gods are to be respected, are to be either forced to surrender or banished altogether.

Plato's new society appears even more regulated, and this regulation will not happen by itself. Thus, Plato suggests that the society should have a secret group taking care that the society stays in the right path. This secret group should consist of the best people of the society. Thus, the secret group works like philosophers in the ideal state, and indeed, one of the issues discussed in the nightly meetings of this group is the development of the philosophy and other sciences: although the guardians of the society are not philosophers, they should at least try to become wiser.