The study of psychology with Plato stands in a fourfold relation to his general theory of the world. The dialectic method, without which Nature would remain unintelligible, is a function of the soul, and constitutes its most essential activity; then soul, as distinguished from body, represents the higher, supersensual element of existence; thirdly, the objective dualism of reality and appearance is reproduced in the subjective dualism of reason and sense; and lastly, soul, as the original spring of movement, mediates between the eternal entities which are unmoved and the material phenomena which are subject to a continual flux. It is very characteristic of Plato that he first strains an antithesis to the utmost and then endeavours to reconcile its extremes by the interposition of one or more intermediate links. So, while assigning this office to soul as a part of the universe, he classifies the psychic functions themselves according to a similar principle. On the intellectual side he places true opinion, or what we should now call empirical knowledge, midway between demonstration and sense-perception. Such at least seems to be the result reached in the Theaetêtus and the Meno. In the Republic a further analysis leads to a somewhat different arrangement. Opinion is placed between knowledge and ignorance; while the possible objects to which it corresponds form a transition from being to not-being. Subsequently mathematical reasoning is distinguished from the higher science which takes cognisance of first principles, and thus serves to connect it with simple opinion; while this again, dealing as it does with material objects, is related to the knowledge of their shadows as the most perfect science is related to mathematics.[138]
Turning from dialectic to ethics, Plato in like manner feels the need of interposing a mediator between reason and appetite. The quality chosen for this purpose he calls θυμός, a term which does not, as has been erroneously supposed, correspond to our word Will, but rather to pride, or the feeling of personal honour. It is both the seat of military courage and the natural auxiliary of reason, with which it co-operates in restraining the animal desires. It is a characteristic difference between Socrates and Plato that the former should have habitually reinforced his arguments for virtue by appeals to self-interest; while the latter, with his aristocratic way of looking at things, prefers to enlist the aid of a haughtier feeling on their behalf. Aristotle followed in the same track when he taught that to be overcome by anger is less discreditable than to be overcome by desire. In reality none of the instincts tending to self-preservation is more praiseworthy than another, or more amenable to the control of reason. Plato’s tripartite division of mind cannot be made to fit into the classifications of modern psychology, which are adapted not only to a more advanced state of knowledge but also to more complex conditions of life. But the characters of women, by their greater simplicity and uniformity, show to some extent what those of men may once have been; and it will, perhaps, confirm the analysis of the Phaedrus to recall the fact that personal pride is still associated with moral principle in the guardianship of female virtue.
If the soul served to connect the eternal realities with the fleeting appearances by which they were at once darkened, relieved, and shadowed forth, it was also a bond of union between the speculative and the practical philosophy of Plato; and in discussing his psychology we have already passed from the one to the other. The transition will become still easier if we remember that the question, ‘What is knowledge?’ was, according to our view, originally suggested by a theory reducing ethical science to a hedonistic calculus, and that along with it would arise another question, ‘What is pleasure?’ This latter enquiry, though incidentally touched on elsewhere, is not fully dealt with in any Dialogue except the Philêbus, which we agree with Prof. Jowett in referring to a very late period of Platonic authorship. But the line of argument which it pursues had probably been long familiar to our philosopher. At any rate, the Phaedo, the Republic, and perhaps the Gorgias, assume, as already proved, that pleasure is not the highest good. The question is one on which thinkers are still divided. It seems, indeed, to lie outside the range of reason, and the disputants are accordingly obliged to invoke the authority either of individual consciousness or of common consent on behalf of their respective opinions. We have, however, got so far beyond the ancients that the doctrine of egoistic hedonism has been abandoned by almost everybody. The substitution of another’s pleasure for our own as the object of pursuit was not a conception which presented itself to any Greek moralist, although the principle of self-sacrifice was maintained by some of them, and especially by Plato, to its fullest extent. Pleasure-seeking being inseparably associated with selfishness, the latter was best attacked through the former, and if Plato’s logic does not commend itself to our understanding, we must admit that it was employed in defence of a noble cause.
The style of polemics adopted on this occasion, whatever else may be its value, will serve excellently to illustrate the general dialectic method of attack. When Plato particularly disliked a class of persons, or an institution, or an art, or a theory, or a state of consciousness, he tried to prove that it was confused, unstable, and self-contradictory; besides taking full advantage of any discredit popularly attached to it. All these objections are brought to bear with full force against pleasure. Some pleasures are delusive, since the reality of them falls far short of the anticipation; all pleasure is essentially transitory, a perpetual becoming, never a fixed state, and therefore not an end of action; pleasures which ensue on the satisfaction of desires are necessarily accompanied by pains and disappear simultaneously with them; the most intense, and for that reason the most typical, pleasures, are associated with feelings of shame, and their enjoyment is carefully hidden out of sight.
Such arguments have almost the air of an afterthought, and Plato was perhaps more powerfully swayed by other considerations, which we shall now proceed to analyse. When pleasure was assumed to be the highest good, knowledge was agreed to be the indispensable means for its attainment; and, as so often happens, the means gradually substituted itself for the end. Nor was this all; for knowledge (or reason) being not only the means but the supreme arbiter, when called on to adjudicate between conflicting claims, would naturally pronounce in its own favour. Naturally, also, a moralist who made science the chief interest of his own life would come to believe that it was the proper object of all life, whether attended or not by any pleasurable emotion. And so, in direct opposition to the utilitarian theory, Plato declares at last that to brave a lesser pain in order to escape from a greater, or to renounce a lesser pleasure in order to secure a greater, is cowardice and intemperance in disguise; and that wisdom, which he had formerly regarded as a means to other ends, is the one end for which everything else should be exchanged.[139] Perhaps it may have strengthened him in this attitude to observe that the many, whose opinion he so thoroughly despised, made pleasure their aim in life, while the fastidious few preferred knowledge. Yet, after a time, even the latter alternative failed to satisfy his restless spirit. For the conception of knowledge resolved itself into the deeper conceptions of a knowing subject and a known object, the soul and the universe, each of which became in turn the supreme ideal. What interpretation should be given to virtue depended on the choice between them. According to the one view it was a purification of the higher principle within us from material wants and passions. Sensual gratifications should be avoided, because they tend to degrade and pollute the soul. Death should be fearlessly encountered, because it will release her from the restrictions of bodily existence. But Plato had too strong a grasp on the realities of life to remain satisfied with a purely ascetic morality. Knowledge, on the objective side, brought him into relation with an organised universe where each individual existed, not for his own sake but for the sake of the whole, to fulfil a definite function in the system of which he formed a part. And if from one point of view the soul herself was an absolutely simple indivisible substance, from another point of view she reflected the external order, and only fulfilled the law of her being when each separate faculty was exercised within its appropriate sphere.
There still remained one last problem to solve, one point where the converging streams of ethical and metaphysical speculation met and mixed. Granted that knowledge is the soul’s highest energy, what is the object of this beatific vision? Granted that all particular energies co-operate for a common purpose, what is the end to which they are subordinated? Granted that dialectic leads us up through ascending gradations to one all-comprehensive idea, how is that idea to be defined? Plato only attempts to answer this last question by re-stating it under the form of an illustration. As the sun at once gives life to all Nature, and light to the eye by which Nature is perceived, so also the idea of Good is the cause of existence and of knowledge alike, but transcends them both as an absolute unity, of which we cannot even say that it is, for the distinction of subject and predicate would bring back relativity and plurality again. Here we seem to have the Socratic paradox reversed. Socrates identified virtue with knowledge, but, at the same time, entirely emptied the latter of its speculative content. Plato, inheriting the idea of knowledge in its artificially restricted significance, was irresistibly drawn back to the older philosophy whence it had been originally borrowed; then, just as his master had given an ethical application to science, so did he, travelling over the same ground in an opposite direction, extend the theory of ethics far beyond its legitimate range, until a principle which seemed to have no meaning, except in reference to human conduct, became the abstract bond of union between all reality and all thought.
Whether Plato ever succeeded in making the idea of Good quite clear to others, or even to himself, is more than we can tell. In the Republic he declines giving further explanations on the ground that his pupils have not passed through the necessary mathematical initiation. Whether quantitative reasoning was to furnish the form or the matter of transcendent dialectic is left undetermined. We are told that on one occasion a large audience assembled to hear Plato lecture on the Good, but that, much to their disappointment, the discourse was entirely filled with geometrical and astronomical investigations. Bearing in mind, however, that mathematical science deals chiefly with equations, and that astronomy, according to Plato, had for its object to prove the absolute uniformity of the celestial motions, we may perhaps conclude that the idea of Good meant no more than the abstract notion of identity or indistinguishable likeness. The more complex idea of law as a uniformity of relations, whether coexistent or successive, had not then dawned, but it has since been similarly employed to bring physics into harmony with ethics and logic.
III.
So far we have followed the evolution of Plato’s philosophy as it may have been effected under the impulse of purely theoretical motives. We have now to consider what form was imposed on it by the more imperious exigencies of practical experience. Here, again, we find Plato taking up and continuing the work of Socrates, but on a vastly greater scale. There was, indeed, a kind of pre-established harmony between the expression of thought on the one hand and the increasing need for its application to life on the other. For the spread of public corruption had gone on pari passu with the development of philosophy. The teaching of Socrates was addressed to individuals, and dealt chiefly with private morality. On other points he was content to accept the law of the land and the established political constitution as sufficiently safe guides. He was not accustomed to see them defied or perverted into instruments of selfish aggrandisement; nor, apparently, had the possibility of such a contingency occurred to him. Still less did he imagine that all social institutions then existing were radically wrong. Hence the personal virtues held a more important place in his system than the social virtues. His attacks were directed against slothfulness and self-indulgence, against the ignorant temerity which hurried some young men into politics before their education was finished, and the timidity or fastidiousness which prevented others from discharging the highest duties of citizenship. Nor, in accepting the popular religion of his time, had he any suspicion that its sanctions might be invoked on behalf of successful violence and fraud. We have already shown how differently Plato felt towards his age, and how much deeper as well as more shameless was the demoralisation with which he set himself to contend. It must also be remembered how judicial proceedings had come to overshadow every other public interest; and how the highest culture of the time had, at least in his eyes, become identified with the systematic perversion of truth and right. These considerations will explain why Greek philosophy, while moving on a higher plane, passed through the same orbit which had been previously described by Greek poetry. Precisely as the lessons of moderation in Homer had been followed by the lessons of justice in Aeschylus, precisely as the religion which was a selfish traffic between gods and men, and had little to tell of a life beyond the grave, was replaced by the nobler faith in a divine guardianship of morality and a retributive judgment after death—so also did the Socratic ethics and the Socratic theology lead to a system which made justice the essence of morality and religion its everlasting consecration.
Temperance and justice are very clearly distinguished in our minds. The one is mainly a self-regarding, the other mainly a social virtue. But it would be a mistake to suppose that the distinction was equally clear to Plato. He had learned from Socrates that all virtue is one. He found himself confronted by men who pointedly opposed interest to honour and expediency to fair-dealing, without making any secret of their preference for the former. Here, as elsewhere, he laboured to dissolve away the vulgar antithesis and to substitute for it a deeper one—the antithesis between real and apparent goods. He was quite ready to imagine the case of a man who might have to incur all sorts of suffering in the practice of justice even to the extent of infamy, torture, and death; but without denying that these were evils, he held that to practise injustice with the accompaniment of worldly prosperity was a greater evil still. And this conviction is quite unconnected with his belief in a future life. He would not have agreed with St. Paul that virtue is a bad calculation without the hope of a reward for it hereafter. His morality is absolutely independent of any extrinsic considerations. Nevertheless, he holds that in our own interest we should do what is right; and it never seems to have entered his thoughts that there could be any other motive for doing it. We have to explain how such a paradox was possible.