A critical history of Greek philosophy

by W. T. Stace

The second group of dialogues is generally connected with the period of Plato's travels. In addition to the influence of Socrates, we have now the influence of the Eleatics, which naturally connects these dialogues with the period of the philosopher's sojourn at Megara. But it is in these dialogues, too, that Plato for the first time [{174}] develops his own special philosophical thesis. This is in fact his great constructive period. The central and governing principle of his philosophy is the theory of Ideas. All else hinges on this, and is dominated by this. In a sense, his whole philosophy is nothing but the theory of Ideas and what depends upon it. It is in this second period that the theory of Ideas is founded and developed, and its relationship to the Eleatic philosophy of Being discussed. We have here the spectacle of Plato's most original thoughts in the pangs of childbirth. He is now at grips with the central problems of philosophy. He is intent upon the thought itself, and cares little for the ornaments of style. He is struggling to find expression for ideas newly-formed in his mind, of which he is not yet completely master, and which he cannot manipulate with ease. Consequently, the literary graces of the first period recede into the background. There is little incident, and no humour. There is nothing but close reasoning, hard and laborious discussion.

The twin dialogues, "Gorgias" and "Theaetetus" are probably the earliest of this group. They result in nothing very definite, and are chiefly negative in character. Plato is here engaged merely in a preparatory clearing of the ground. The "Gorgias" discusses and refutes the Sophistic identification of virtue and pleasure, and attempts to show, as against it, that the good must be something objectively existent, and independent of the pleasure of the individual. The "Theaetetus," similarly, shows that truth is not, as the Sophists thought, merely the subjective impression of the individual, but is something objectively true in itself. The other [{175}] dialogues of the group are the "Sophist," the "Statesman," and the "Parmenides." The "Sophist" discusses Being and not-being, and their relationship to the theory of Ideas. The "Parmenides" inquires whether the absolute reality is to be regarded, in the manner of the Eleatics, as an abstract One. It gives us, therefore, Plato's conception of the relation of his own philosophy to Eleaticism.

The dialogues of the third group are the work of Plato's maturity. He has now completely mastered his thought, and turns it with ease in all directions. Hence the style returns to the lucidity and purity of the first period. If the first period was marked chiefly by literary grace, the second by depth of thought, the third period combines both. The perfect substance is now moulded in the perfect form. But a peculiarity of all the dialogues of this period is that they take it for granted that the theory of Ideas is already established and familiar to the reader. They proceed to apply it to all departments of thought. The second period was concerned with the formulation and proof of the theory of Ideas, the third period undertakes its systematic application. Thus the "Symposium," which has for its subject the metaphysic of love, attempts to connect man's feeling for beauty with the intellectual knowledge of the Ideas. The "Philebus" applies the theory of Ideas to the sphere of ethics, the "Timaeus" to the sphere of physics, and the "Republic" to the sphere of politics. The "Phaedo" founds the doctrine of the immortality of the soul upon the theory of Ideas. The "Phaedrus" is probably to be grouped with the "Symposium." The beauty, grace, and lucidity of the style, and the fact that it assumes throughout that [{176}] the theory of Ideas is a thing established, lead us to the belief that it belongs to the period of Plato's maturity. Zeller's theory that it was written at the beginning of the second period, and is then offered to the reader as a sort of sweetmeat to induce him to enter upon the laborious task of reading the "Sophist," the "Statesman," and the "Parmenides," seems to be far-fetched and unnecessary. [Footnote 12]

[Footnote 12: Zeller's Plato and the Older Academy, chap. iii.]

If the second is the great constructive period of Plato's life, the third may be described as his systematic and synthetic period. Every part of his philosophy is here linked up with every other part. All the details of the system are seen to flow from the one central principle of his thought, the theory of Ideas. Every sphere of knowledge and being is in turn exhibited in the light of that principle, is permeated and penetrated by it.

The plan for expounding Plato which first suggests itself is to go through the dialogues, one by one, and extract the doctrine of each successively. But this suggestion has to be given up as soon as it is mentioned. For although the philosophy of Plato is in itself a systematic and coherent body of thought, he did not express it in a systematic way. On the contrary, he scatters his ideas in all directions. He throws them out at random in any order. What logically comes first often appears last. It may be found at the end of a dialogue, and the next step in reasoning may make its appearance at the beginning, or even in a totally different dialogue. If, therefore, we are to get any connected view of the system, we must abandon Plato's own order of exposition, and piece the thought together for ourselves. We must begin [{177}] with what logically comes first, wherever we may find it, and proceed with the exposition in the same manner.

A similar difficulty attends the question of the division of Plato's philosophy. He himself has given us no single and certain principle of division. But the principle usually adopted divides his philosophy into Dialectic, Physics, and Ethics. Dialectic, or the theory of Ideas, is Plato's doctrine of the nature of the absolute reality. Physics is the theory of phenomenal existence in space and time, and includes therefore the doctrine of the soul and its migrations, since these are happenings in time. Ethics includes politics, the theory of the duty of man as a citizen, as well as the ethics of the individual. Certain portions of the system, the doctrine of Eros, for example, do not fall very naturally into any of these divisions. But, on the other hand, though some dialogues are mixed as to their subject matter, others, and those the most important, fall almost exclusively into one or other division. For example, the "Timaeus," the "Phaedo," and the "Phaedrus," are physical. The "Philebus," the "Gorgias," and the "Republic," are ethical. The "Theaetetus," the "Sophist," and the "Parmenides," are dialectical.

2. The Theory of Knowledge.

The theory of Ideas is itself based upon the theory of knowledge. What is knowledge? What is truth? Plato opens the discussion by telling us first what knowledge and truth are not. His object here is the refutation of false theories. These must be disposed of to clear the ground preparatory to positive exposition. The first such false theory which he attacks is that knowledge [{178}] is perception. To refute this is the main object of the "Theaetetus." His arguments may be summarized as follows:--

(1) That knowledge is perception is the theory of Protagoras and the Sophists, and we have seen to what results it leads. What it amounts to is that what appears to each individual true is true for that individual. But this is at any rate false in its application to our judgment of future events. The frequent mistakes which men make about the future show this. It may appear to me that I shall be Chief Justice next year. But instead of that, I find myself, perhaps, in prison. In general, what appears to each individual to be the truth about the future frequently does not turn out so in the event.