rightly saw a successor of Zeno, came to scepticism from the standpoint of Eleatic henism. In other words, Aristippus was sceptical because, taking into account the subjective element in sensation, he found himself compelled to regard what are called “things” as successions of feelings, which feelings are themselves absolutely distinct from one another; while Antisthenes and Euclides were sceptical because, like Zeno, they did not understand how the same thing could at the same moment bear various and inconsistent epithets, and consequently conceived all predication which was not identical to be illegitimate. Thus Aristippus recognized only feelings, denying things; Antisthenes recognized things, denying attributions; and it is probable that in this matter Euclides was at one with him. For, though since Schleiermacher many historians, unnecessarily identifying the εἰδῶν φίλοι of Plato's Sophist with the Megarians, have ascribed to Euclides a theory of “ideas,” and on the strength of this single passage thus conjecturally interpreted have added a new chapter to the history of Megarianism, it is difficult, if not impossible, to see how, if the founder of the school had broken loose from the trammels of the Zenonian paradox, his successors, and amongst them Stilpo, should have reconciled themselves, as they certainly did, to the Cynic denial of predication.
While the “incomplete Socratics” made no attempt to overpass the limits which Socrates had imposed upon himself, within those limits they occupied each his department. Aristippus, a citizen of the world, drawn to Athens by the fame of Socrates, and retained there by the sincere affection which he conceived for him, interpreted the ethical doctrine of Socrates in accordance with his own theory of pleasure, which in its turn came under the refining influence of Socrates's theory of φρόνησις. Contrariwise, Antisthenes, a rugged but not ungenerous nature, a hater of pleasure, troubled himself little about ethical theory and gave his life to the imitation of his master's asceticism. Virtue, he held, depended upon “works,” not upon arguments or lessons; all that was necessary to it was the strength of a Socrates (Diog. Laërt. vi. 11). Yet here too the Socratic theory of φρόνησις had a qualifying effect; so that Cyrenaic hedonism and Cynic asceticism sometimes exhibit unexpected approximations. The teaching of Euclides, though the Good is still supposed to be the highest object of knowledge, can hardly be said to have an ethical element; and in consequence of this deficiency the dialectic of Socrates degenerated in Megarian hands, first into a series of exercises in fallacies, secondly into a vulgar and futile eristic. In fact, the partial Socraticisms of the incomplete Socratics necessarily suffered, even within their own narrow limits, by the dismemberment which the system had undergone. Apparently the maieutic theory of education was not valued by any of the three; and, however this may be, they deviated from Socratic tradition so far as to establish schools, and, as it would seem, to take fees like the professional educators called Sophists.
Of the relations in which the metaphysic of Plato stood to the Socratic search for definitions there are of necessity almost as many theories as there are interpretationsPlato's Metaphysical Theories. of the Platonic system. Hence in this place the writer must content himself with a summary statement of his own views. Initiated into philosophical speculation by the Heraclitean Cratylus, Plato began his intellectual life as an absolute sceptic, the followers of Heraclitus having towards the end of the 5th century pushed to its conclusion the unconscious scepticism of their master. There would have been then nothing to provoke surprise, if, leaving speculation, Plato had given himself to politics. In 407, however, he became acquainted with Socrates, who gave to his thoughts a new direction. Plato now found an occupation for his intellectual energies, as Socrates had done, in the scrutiny of his beliefs and the systematization of his principles of action. But it was not until the catastrophe of 399 that Plato gave himself to his life's work. An exile, cut off from political ambitions, he came forward as the author of dialogues which aimed at producing upon readers the same effect which the voice of the master had produced upon hearers. For a time he was content thus to follow in the steps of Socrates, and of this period we have records in those dialogues which are commonly designated Socratic. But Plato had too decided a bent for metaphysics to linger long over propaedeutic studies. Craving knowledge—not merely provisional and subjective knowledge of ethical concepts, such as that which had satisfied Socrates, but knowledge of the causes and laws of the universe, such as that which the physicists had sought—he asked himself what was necessary that the “right opinion” which Socrates had obtained by abstraction from particular instances might be converted into “knowledge” properly so called. In this way Plato was led to assume for every Socratic universal a corresponding unity, eternal, immutable, suprasensual, to be the cause of those particulars which are called by the common name. On this assumption the Socratic definition or statement of the “what” of the universal, being obtained by the inspection of particulars, in some sort represented the unity, form, or “idea” from which they derived their characteristics, and in so far was valuable; but, inasmuch as the inspection of the particulars was partial and imperfect, the Socratic definition was only a partial and imperfect representation of the eternal, immutable, suprasensual, idea. How, then, was the imperfect representation of the idea to be converted into a perfect representation? To this question Plato's answer was vague and tentative. By constant revision of the provisional definitions which imperfectly represented the ideas he hoped to bring them into such shapes that they should culminate in the definition of the supreme principle, the Good, from which the ideas themselves derive their being. If in this way we could pass from uncertified general notions, reflections of ideas, to the Good, so as to be able to say, not only that the Good causes the ideas to be what they are, but also that the Good causes the ideas to be what we conceive them, we might infer, he thought, that our definitions, hitherto provisional, are adequate representations of real existences. But the Platonism of this period had another ingredient. It has been seen that the Eleatic Zeno had rested his denial of plurality upon certain supposed difficulties of predication, and that they continued to perplex Antisthenes as well as perhaps Euclides and others of Plato's contemporaries. These difficulties must be disposed of, if the new philosophy was to hold its ground; and accordingly, to the fundamental assertion of the existence of eternal immutable ideas, the objects of knowledge, Plato added two subordinate propositions, namely, (1) “the idea is immanent in the particular,” and (2) “there is an idea wherever a plurality of particulars is called by the same name.” Of these propositions the one was intended to explain the attribution of various and even inconsistent epithets to the same particular at the same time, whilst the other was necessary to make this explanation available in the case of common terms other than the Socratic universals. Such was the Platonism of the Republic and the Phaedo, a provisional ontology, with a scheme of scientific research, which, as Plato honestly confessed, was no more than an unrealized aspiration. It was the non-Socratic element which made the weakness of this, the earlier, theory of ideas. Plato soon saw that the hypothesis of the idea's immanence in particulars entailed the sacrifice of its unity, whilst as a theory of predication that hypothesis was insufficient, because applicable to particulars only, not to the ideas themselves. But with clearer views about relations and negations the paradox of Zeno ceased to perplex; and with the consequent withdrawal of the two supplementary articles the development of the fundamental assumption of ideas, eternal, immutable, suprasensual, might be attempted afresh. In the more definite theory which Plato now propounded the idea was no longer a Socratic universal perfected and hypostatized, but rather the perfect type of a natural kind, to which type its imperfect members were related by imitation, whilst this relation was metaphysically explained by means of a “thoroughgoing idealism” (R. D. Archer-Hind). Thus, whereas in the earlier theory of ideas the ethical universals of Socrates had been held to have a first claim to hypostatization in the world of ideas, they are now peremptorily excluded, whilst the idealism which reconciles plurality and unity gives an entirely new significance to so much of the Socratic element as is still retained.
The growth of the metaphysical system necessarily influenced Plato's ethical doctrines; but here his final position is less remote from that of Socrates.Plato's Ethical Theories. Content in the purely Socratic period to elaborate and to record ethical definitions such as Socrates himself might have propounded, Plato, as soon as the theory of ideas offered itself to his imagination, looked to it for the foundation of ethics as of all other sciences. Though in the earlier ages both of the individual and of the state a sound utilitarian morality of the Socratic sort was useful, nay valuable, the morality of the future should, he thought, rest upon the knowledge of the Good. Such is the teaching of the Republic. But with the revision of the metaphysical system came a complete change in the view which Plato took of ethics and its prospects. Whilst in the previous period it had ranked as the first of sciences, it was now no longer a science; because, though Good absolute still occupied the first place, Good relative and all its various forms—justice, temperance, courage, wisdom—not being ideas, were incapable of being “known.” Hence it is that the ethical teaching of the later dialogues bears an intelligible, though perhaps unexpected, resemblance to the simple practical teaching of the unphilosophical Socrates.
Yet throughout these revolutions of doctrine Plato was ever true to the Socratic theory of education. His manner indeed changed; for, whereas in the earlier dialogues the characteristics of the master are studiously and skilfully preserved, in the later dialogues Socrates first becomes metaphysical, then ceases to be protagonist, and at last disappears from the scene. But in the later dialogues, as in the earlier, Plato's aim is the aim which Socrates in his conversation never lost sight of, namely, the dialectical improvement of the learner.
Bibliography.—Of the histories of Greek philosophy the most convenient for the study of Socrates's life and work is Zeller's Philosophie d. Griechen. The part in question has been translated into English under the title of Socrates and the Socratic Schools (London, 1877). For a list of special treatises, see Ueberweg in his Grundriss d. Geschichte d. Philosophie. The following sources of information may be specially mentioned: F. Schleiermacher, “Ueber d. Werth d. Sokrates als Philosophen,” in Abh. d. berliner Akad. d. Wissensch. (1815) and Werke, iii. 2, 287-308, translated into English by C. Thirlwall in the Philological Museum (Cambridge, 1833), ii. 538-555; L. F. Lélut, Du Démon de Socrate (Paris, 1836, 1856), reviewed by E. Littré in Médecine et médecins (Paris, 1872); G. Grote, History of Greece, ch. lxviii., and Plato and the Other Companions