For Plato, this question does not really exist. Although his dramatic sense leads him to state the position of Thrasymachns forcibly, he is quite unaware of its strength, and allows himself to be grossly unfair in arguing against it. Plato is convinced that there is «the Good,» and that its nature can be ascertained; when people disagree
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about it, one, at least, is making an intellectual error, just as much as if the disagreement were a scientific one on some matter of fact.
The difference between Plato and Thrasymachus is very important, but for the historian of philosophy it is one to be only noted, not decided. Plato thinks he can prove that his ideal Republic is good; a democrat who accepts the objectivity of ethics may think that he can prove the Republic bad; but any one who agrees with Thrasymachus will say: «There is no question of proving or disproving; the only question is whether you like the kind of State that Plato desires. If you do, it is good for you; if you do not, it is bad for you. If many do and many do not, the decision cannot be made by reason, but only by force, actual or concealed.» This is one of the issues in philosophy that are still open; on each side there are men who command respect. But for a very long time the opinion that Plato advocated remained almost undisputed.
It should be observed, further, that the view which substitutes the consensus of opinion for an objective standard has certain consequences that few would accept. What are we to say of scientific innovators like Galileo, who advocate an opinion with which few agree, but finally win the support of almost everybody? They do so by means of arguments, not by emotional appeals or state propaganda or the use of force. This implies a criterion other than the general opinion. In ethical matters, there is something analogous in the case of the great religious teachers. Christ taught that it is not wrong to pluck ears of corn on the Sabbath, but that it is wrong to hate your enemies. Such ethical innovations obviously imply some standard other than majority opinion, but the standard, whatever it is, is not objective fact, as in a scientific question. This problem is a difficult one, and I do not profess to be able to solve it. For the present, let us be content to note it.
Plato’s Republic, unlike modern Utopias, was perhaps intended to be actually founded. This was not so fantastic or impossible as it might naturally seem to us. Many of its provisions, including some that we should have thought quite impracticable, were actually realized at Sparta. The rule of philosophers had been attempted by Pythagoras, and in Plato’s time Archytas the Pythagorean was politically influential in Taras (the modern Taranto) when Plato visited Sicily and southern Italy. It was a common practice for cities to employ a sage
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to draw up their laws; Solon had done this for Athens, and Protagoras for Thurii. Colonies, in those days, were completely free from control by their parent cities, and it would have been quite feasible for a band of Platonists to establish the Republic on the shores of Spain or Gaul. Unfortunately chance led Plato to Syracuse, a great commercial city engaged in desperate wars with Carthage; in such an atmosphere, no philosopher could have achieved much. In the next generation, the rise of Macedonia had made all small States antiquated, and had brought about the futility of all political experiments in miniature.
CHAPTER XV The Theory of Ideas
THE middle of the Republic, from the later part of Book V to the end of Book VII, is occupied mainly with questions of pure philosophy, as opposed to politics. These questions are introduced by a somewhat abrupt statement:
Until philosophers are kings, or the kings and princes of this world have the spirit and power of philosophy, and political greatness and wisdom meet in one, and those commoner natures who pursue either to the exclusion of the other are compelled to stand aside, cities will never have rest from these evils—no, nor the human race, as I believe—and then only will this our State have a possibility of life and behold the light of day.
If this is true, we must decide what constitutes a philosopher, and what we mean by «philosophy.» The consequent discussion is the most famous part of the Republic, and has perhaps been the most in. fluential. It has, in parts, extraordinary literary beauty; the reader may disagree (as I do) with what is said, but cannot help being moved by it.
Plato’s philosophy rests on the distinction between reality and appearance, which was first set forth by Parmenides; throughout the
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discussion with which we are now concerned, Parmenidean phrases and arguments are constantly recurring. There is, however, a religious tone about reality, which is rather Pythagorean than Parmenidean; and there is much about mathematics and music which is directly traceable to the disciples of Pythagoras. This combination of the logic of Parmenides with the other-worldliness of Pythagoras and the Orphics produced a doctrine which was felt to be satisfying to both the intellect and the religious emotions; the result was a very powerful synthesis, which, with various modifications, influenced most of the great philosophers, down to and including Hegel. But not only philosophers were influenced by Plato. Why did the Puritans object to the music and painting and gorgeous ritual of the Catholic Church? You will find the answer in the tenth book of the Republic. Why are children in school compelled to learn arithmetic? The reasons are given in the seventh book.
The following paragraphs summarize Plato’s theory of ideas.
Our question is: What is a philosopher? The first answer is in accordance with the etymology: a philosopher is a lover of wisdom. But this is not the same thing as a lover of knowledge, in the sense in which an inquisitive man may be said to love knowledge; vulgar curiosity does not make a philosopher. The definition is therefore amended: the philosopher is a man who loves the «vision of truth.» But what is this vision?
Consider a man who loves beautiful things, who makes a point of being present at new tragedies, seeing new pictures, and hearing new music. Such a man is not a philosopher, because he loves only beautiful things, whereas the philosopher loves beauty in itself. The man who only loves beautiful things is dreaming, whereas the man who knows absolute beauty is wide awake. The former has only opinion; the latter has knowledge.
What is the difference between «knowledge» and «opinion»? The man who has knowledge has knowledge of something, that is to say, of something that exists, for what does not exist is nothing. (This is reminiscent of Parmenides.) Thus knowledge is infallible, since it is logically impossible for it to be mistaken. But opinion can be mistaken. How can this be? Opinion cannot be of what is not, for that is impossible; nor of what is, for then it would be knowledge. Therefore opinion must be of what both is and is not.
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But how is this possible? The answer is that particular things always partake of opposite characters: what is beautiful is also, in some respects, ugly; what is just is, in some respects, unjust; and so on. All particular sensible objects, so Plato contends, have this contradictory character; they are thus intermediate between being and not-being, and are suitable as objects of opinion, but not of knowledge. «But those who see the absolute and eternal and immutable may be said to know, and not to have opinion only.»
Thus we arrive at the conclusion that opinion is of the world presented to the senses, whereas knowledge is of a super-sensible eternal world; for instance, opinion is concerned with particular beautiful things, but knowledge is concerned with beauty in itself.
The only argument advanced is that it is self-contradictory to suppose that a thing can be both beautiful and not beautiful, or both just and not just, and that nevertheless particular things seem to combine such contradictory characters. Therefore particular things are not real. Heraclitus had said: «We step and do not step into the same rivers; we are and are not.» By combining this with Parmenides we arrive at Plato’s result.
There is, however, something of great importance in Plato’s doctrine which is not traceable to his predecessors, and that is the theory of «ideas» or «forms.» This theory is partly logical, partly metaphysical. The logical part has to do with the meaning of general words. There are many individual animals of whom we can truly say «this is a cat.» What do we mean by the word «cat»? Obviously something different from each particular cat. An animal is a cat, it would seem, because it participates in a general nature common to all cats. Language cannot get on without general words such as «cat,» and such words are evidently not meaningless. But if the word «cat» means anything, it means something which is not this or that cat, but some kind of universal cattyness. This is not born when a particular cat is born, and does not die when it dies. In fact, it has no position in space or time; it is «eternal.» This is the logical part of the doctrine. The arguments in its favour, whether ultimately valid or not, are strong, and quite independent of the metaphysical part of the doctrine.
According to the metaphysical part of the doctrine, the word «cat» means a certain ideal cat, «the cat,» created by God,
