Watson, John. “Plato and Protagoras.” The Philosophical Review 16, no. 5 (1907): 469. https://doi.org/10.2307/2177231
THE present controversy between the representatives of the loose body of opinion, variously known as 'pragmatism, ‘humanism,' or 'radical empiricism,' and the exponents of the belief in a science of reality, recalls the earlier combat between the Sophists and Plato. In a sense the grounds of disagreement are the same. The modern like the ancient Sophist has risen in revolt against the tyranny of an established creed, and in defense the rights of the individual; and he displays a decided aversion from investigations into the ultimate nature of things which he assumes to be incapable of solution accompanied by strong faith in the essential soundness of the common moral consciousness. His opponent, on the other hand, like Plato, insists upon the necessity of a reasoned body of truth, to which the individual must yield assent; and he maintains that no solid foundation can be found either for knowledge or morality unless it is possible to comprehend in principle the ultimate nature of things. An antagonism so vital and fundamental obviously admits of no compromise; but perhaps it is not beyond reasonable hope that better understanding of the strength of each other's position will at least result in the elimination of irrelevant issues and prepare the way for a solution of the problem, if such a solution is possible at all. Partly as a small contribution in this direction, I propose to recall the attitude of Plato, the representative of what in a large sense may be called a rational idealism, towards Protagoras, whom a recent exponent of 'pragmatism,' or perhaps I should say of ' humanism,' is willing to regard as his philosophical progenitor.
The development of Greek mythology, as we know, consisted in a regress from nature to man, and from multiplicity to unity; but, as this regress did not fairly lift the mind of Greece above the pictorial stage of thought, the time inevitably came when an attempt was made to grasp the world and human life in a more adequate way. Thus, arose the speculations of the early philosophers and the subsequent doctrines of the Sophists and theocratic schools. And it was only natural that the philosophy of Greece should repeat, at the stage of reflective thought, the process by which the religion of Greece had advanced from object to subject, from nature to man. In its first phase philosophy assumed that the real was the external, and therefore it sought to interpret all reality in terms of nature; and it was only when this first vein of reflection had been exhausted, that the Greek mind turned its attention to the problem of human life. It was felt, rather than clearly seen, that no principle drawn from the sensible world could adequately account for the peculiar nature of man; and thus, began a new phase of speculation. Nature was no longer regarded as self-explanatory; the key to the riddle of existence was therefore sought in man. The first step in the new direction was taken by the Sophists, who expressed the revolt against a mode of thought which turned away from human life or sought to assimilate it to the unconscious movements of external nature. This 'humanistic' attitude, as we may fairly call it, arose in the reaction from a philosophy which attempted to explain all things solely from the point of view of the object. The Sophists adopted very much the same attitude towards the naturalism of their day as the early philosophers towards the current mythology. To all speculations on the ultimate nature of things they were indifferent or openly hostile; for either, like Protagoras, they refused to admit that such enquiries had any real bearing on human life, or, with Gorgias, they explicitly denied that a knowledge of the objective world was possible for man.
Socrates so far agreed with the Sophists, that he doubted or disbelieved in the possibility of comprehending the universe as a whole; but, in contrast to them, he denied that the prevalent moral beliefs of men were the only, or the sufficient, basis of morality. The reason, or one of the reasons, relied upon by theming defense of their view that morality is a matter of expediency, viz., that the moral beliefs of different nations and individuals are mutually contradictory, was employed by him to inculcate the duty of seeking for impregnable principles of conduct. Socrates, as we may say, urged the necessity of a metaphysic of morality, while denying the necessity of a metaphysic of reality. His problem therefore was, to determine, on the basis of reason, wherein the highest life of man consists. This problem, as he claimed, could only be solved by a clear comprehension of the end towards which all effort should be directed, and a definite knowledge of the means by which it may be realized. To be really virtuous, as it seemed to him, the agent must have a clear consciousness of what he ought to aim at, and why certain acts are good; and until he has attained to this self-knowledge, his conduct may conform to what is customary, but it can have no moral value. The artist in life is not made so by accident, and if he were, he would deserve no credit for what lay beyond his range of vision. On the other hand, it is Socrates's belief that a clear consciousness of the true end of life will inevitably be followed by the performance of the acts by which it may be realized. Hence "virtue is knowledge," both in the sense that without knowledge of the end to be realized there is no morality, and that, as man is so constituted that he cannot do otherwise than follow what he knows to be best, knowledge of that end must result in virtuous acts. Now, the end of life, as that in which Aman must find his true good, obviously is 'happiness,' or 'wellbeing. ‘The ambiguity of the term however, inevitably led to a divergence of view in the followers of Socrates, and even in the mind of Plato, his greatest pupil. This divergence comes to clear expression in the Protagoras, which has justly been regarded as marking the transition from the dialogues which are occupied with the exposition and illustration of the Socratic view of morality to those in which Plato works out a higher conception of his own. What light does this dialogue throw upon his attitude towards Protagoras? It will hardly be said that Plato has here made a 'travesty' of the doctrine of Protagoras: if there is any 'travesty' at all, it is rather of the Socratic thesis, that " virtue is knowledge." But, in truth, no valuable result is to be derived from the study of a great writer, which does not assume absolute good faith on his part. Even in the case of the Theaetetus, as I believe, Plato is not only speculatively, but even historically, just; and in the Protagoras he is undoubtedly not only just, but even generous, in his picture of the great Sophist.
There are two main points in the dialogue, which should be clearly distinguished: firstly, the contrast of method in Protagoras and Socrates; and, secondly, the attitude of each towards current morality. As to the former, the method of Protagoras is rhetorical, and therefore does not seek to go behind average public opinion; while that of Socrates is dialectical and aims at a systematic connection of moral ideas. It is obvious that this fundamental contrast of method is quite compatible with the fact that, so far as results are concerned, Protagoras comes nearer to the truth than Socrates. If truth, as our modern pragmatists Tellus, consists in the ideas that work out best, there can be little doubt that the assumption running through the whole of Protagoras’s statements, that the public conscience is on the whole sound, is more defensible than the doctrine of Socrates that no moral judgment has any ethical value which has not been explicitly brought into relation with the one end of life and seen to be subordinate to it. A different judgment must be passed upon the value of Protagoras's ethical doctrine when we look at it as simply the formulation of the current ideas of his time. Theosophist, as Protagoras claims, merely clearly states the moral ideas which are present in the minds of all; ideas which owe their origin partly to a divinely implanted instinct, and partly to the influence of men upon each other in society. Thus, virtues are not a special art, presupposing an original endowment and a particular training, but a common possession, which everyone can teach, and does teach, to his neighbor. The Sophist makes no pretensions to an exceptional knowledge of morality; all that he professes to do is to state in a better form what all reasonable men believe; and this power, in fact, is his only claim to recognition. He is a better teacher of morality than others, but by no means its only teacher. Now, there can be no doubt that Protagoras here insists upon an aspect of truth which Socrates, with his rigid doctrine, ignores: the truth, that morality is not the product of pure reflection, but exists prior to reflection and as the result of the process by which the individual, as a member of a civilized community, is unconsciously moralized. But, while thesis true, the method of Protagoras, as Plato thinks, has this fundamental defect: that it virtually assumes the ultimate validity of current morality, just because it makes no attempt to trace it back to its principle; and in doing so, it bars the way to a higher form of morality. The force of rhetoric lies in its appeal to the average mind, and the rhetorician, as Plato indicates by the manner in which Protagoras falls before Socrates after two or three blows, is no match for the dialectician, just because he has always assumed the absoluteness of current moral ideas, and is therefore perplexed and confused when he is forced to give a reason for the faith that is in him.
It may of course be said that Protagoras, who could confidently count on the response of the popular conscience, was on a higher level than Socrates, with his one-sided ' intellectualism. ‘But this defense overlooks the fact that truth is something more than mere conformity with the nature of things, including as it does a comprehension by the individual of the grounds of that conformity. In assuming the attitude of the spokesman of customary ideas, Protagoras was either committing himself to a bundle of contradictions, or tacitly assuming a principle contradictory to his rhetorical method. For current moral ideas, even of the same people in the same age, and much more of different peoples in different ages, are not perfectly homogeneous, but are made up of incompatible elements. By his method Protagoras was led to pass lightly over these contradictions, and to appeal to an accepted body of ethical opinion, representing on the whole the better mind of Greece. And no doubt there was a certain justification for this light-hearted method of ignoring differences; but the justification must ultimately lie in the principle that ethic truth, like other truth, is the expression of a rational and therefore self-consistent body of doctrine. In other words, the appeal to the public conscience is either an appeal to the reason latent in all men, or it is a mere appeal to popular prejudice. Now, it is surely obvious, that, if morality is to be the expression of the growing moral consciousness of the race, the first step in the transition from the assumptions and inconsistencies of custom must consist in bringing current moral ideas to the test of some universal principle. Upon this presupposition the method of Socrates was based; and, therefore, whatever its immediate success might be, as a method it was infinitely superior to that of Protagoras.
What has just been said as to the contrasted methods of Protagoras and Socrates partly anticipates the second point, viz., the attitude of each towards customary morality. The problem of Protagoras was not to discover the rational basis of the particular ethical judgments men make, much less to search for a single principle to which they might all be referred, but merely to frame good working conception which should serve as a guide for the ordinary well-disposed citizen. Socrates, on the other hand, refused to be satisfied with anything short of a science of morals, in which each virtue was clearly seen to follow from the idea of a single supreme end. In the Protagoras, Plato represents Socrates as seeking to defend this view on the basis of what has been called ‘psychological hedonism,' i.e., the doctrine that nothing ever is or can be desired but pleasure and the absence of pain. If this is admitted, the thesis, that virtue is knowledge, as it is argued, maybe successfully defended. For, in the first place, all acts which result in greater pleasure than pain will be good; and, in the second place, since nothing but good ever is desired, he who knows the felicific consequences of any proposed course of conduct will inevitably do those acts which result in a maximum of pleasure, i.e. he will act virtuously. Thus, as Socrates argues, a science of morality, based on a calculus of pleasures and pains, may be constructed, and, as a consequence, men may be taught the art of good citizenship, just as they learn the arts of architecture or painting or sculpture. If we ask which of these views is Plato's own, the answer must be both, and yet neither; for, though in the Protagoras no definite conclusion is reached, the clear opposition of the two antagonistic views, represented by Protagoras and Socrates respectively, is a proof that Plato entered sympathetically into each, while satisfied with neither. What he found suggested in the view of Protagoras was, that the individual is undoubtedly moralized by society prior to any construction on his part of a science of conduct; while in the demand of Socrates for such a science he recognized the legitimate claim of the reason to accept only that which is rational. On the other hand, the pupil of Socrates could never be induced to acquiesce in the view of Protagoras, that morality has no other justification than custom and convention; nor could he ultimately be satisfied with the precarious and shifting basis offered by hedonism. The dialogue must therefore be regarded as exhibiting the strength and weakness of both views, and as presenting for subsequent solutions the problem of reconciling the ordinary moral judgments of men with the claim of philosophy to accept nothing that is not rational. We have now to ask whether Plato has been less just to Protagoras in the Theaetetus than in the dialogue just considered. Here, if anywhere, must be found the evidence for the charge of misapprehension or distortion which has been made by various writers ever since Crete's famous defense of the Sophists.
The first question is whether Plato has shown indifference to historical accuracy in his characterization of Protagoras. After the convincing essay of Natori, it seems impossible that anyone can regard this charge as capable of being substantiated. In the dialogue it is assumed that the treatise of Protagoras, “On Truth," was accessible, and could be consulted in verification of any statement that was made. When, therefore, Socrates expressly refers to some saying as having been made by Protagoras, it may fairly be claimed that what is so referred to is the veritable doctrine of the distinguished Sophist. Applying this test, there can be no doubt as to the actual doctrine of Protagoras. Man, as he held, is the measure of all things, of those things that are, that they are; of those things that are not, that they are not. What is meant by this is, that as each thing appears to me, it is to me; as it appears to you, it is to you. Sometimes, when the same wind is blowing, one of us is cold, the other not; and one is slightly cold, the other exceedingly. Now, it cannot be that the wind in itself is cold or not cold; but to one who feels it cold, it is cold, to one who does not feel it so, it is not so. Thus, the same wind appears cold to one, not cold to another.
In Plato's estimation, then, the doctrine of Protagoras was that the individual man is the measure of what is and is not. This, indeed, was the universal view taken of the doctrine of Protagoras by ancient writers. Nor is there any discrepancy between the representation of Protagoras already considered and that now given; on the contrary, nothing is more natural than that one who assumed that what everyone believes to be good is to be taken as good, should see nothing absurd in the doctrine that each man must be guided by what seems to him true, and especially by what is directly presented to him by his senses. There is no improbability in the supposition, that Protagoras was unconscious of any contradiction in maintaining at once the relativity of each man's apprehension and the identity of an object with itself apart from such apprehension; a want of clearness of thought which is not surprising, when we consider that the same confusion reappears in the writings of our 'pragmatic' friends. There is, therefore, no reason to doubt the correctness of Plato’s view, that Protagoras regarded the individual man as the measure of truth for himself.
The doctrine of Protagoras is first connected by Plato with the definition of knowledge as sensible perception, put in the mouth of Theaetetus, and then with the Hera clitic doctrine that "all things are in flux." A careful study of the dialogue, however, makes it clear that this connection is not said by Plato to have been stated by Protagoras himself, in his treatise on Truth. No doubt Protagoras is declared to have "said the same thing as Theaetetus in a different way;” but, on the other hand, “the opinion of the great sage Protagoras, that man is the measure of all things," is expressly contrasted with " the view of Theaetetus, that, given certain premises, perception is knowledge." Moreover, Plato indicates that Protagoras did not, at least with any definiteness, connect his own view with the Hera clitic doctrine. He spoke “in a parable," as Plato puts it, "to the common herd, like you and me, and only told the truth, 'his Truth’ in secret to his disciples." As Plato also speaks of the 'mysteries' of certain 'brethren’ and of "the hidden 'truth' of a famous man or rather famous school, “it is evident that there was nothing in the work of Protagoras about the doctrine of 'flux'; though no doubt his disciples, possibly at some suggestion from him, may have sought to defend their sensationalist theory by reference to that doctrine. But while Plato makes it quite clear that the three theses were not brought into relation with one another by Protagoras himself, he also maintains that there is a close inner connection between them; so close, indeed, that they may be regarded as integral elements in a single comprehensive theory. His interest in this theory was not polemical but constructive, as may be seen from a short summary of the development of his own thought in the interval between the composition of the Protagoras and the Theaetetus.
The Protagoras, as we have seen, virtually calls into question the abrupt opposition of ignorance and knowledge which was characteristic of Socrates, suggesting that the real opposition, at least in the case of moral judgments, is between opinion and knowledge. The view thus suggested is explicitly stated in the Meno and Gorgias. The ordinary moral judgments of men are not false, but merely confused; they seem to be in particular, while in reality what gives them their force is the universal principle which they tacitly presuppose. In the Menthe correct, yet unconscious, application of the universal principles explained by the half-mythical doctrine of 'reminiscence,' the substance of which is, that the advance from opinion to knowledge consists in bringing to clear and explicit expression the universal principle already obscurely presenting the particular judgments of the ordinary consciousness. Thus, when a man who pays his debts is pronounced just, it is tacitly implied that he was governed by the universal principle of justice, though he did not think of it in that way, and is unable to define justice when asked to do so. Here, therefore, it is suggested that human life is always guided by universal principles or ' ideas.' Ifrit is asked why, on that supposition, a science of conduct is necessary, Plato answers that the explicit recognition of moral principles is the only safeguard against vacillating and inconsistent conduct, and the sole guarantee of a life organized on a definite plan. In the Gorgias it is added that, in their ordinary moral judgments, men are not only guided by universal principles, but they always act under the idea of a single supreme principle, the 'idea of the Good.' No doubt they are apt to suppose that they are seeking some particular object, such as health, wealth, or honor, but what they will, as distinguished from what they wish, is always 'the Good,' all other things being really desired as a means to the realization of this supreme end. The confusion between the real and the apparent object of desire explains the prejudicial influence of a false rhetoric; for the rhetorician may appeal to what men wish, overlooking what they will, and may therefore, encourage false and selfish views of life. Hence the importance of a science of ethics, which shall bring to light the ultimate principle of action and enable men to organize the whole of their life by reference to it.
As the result of the discussions embodied in these three dialogues, Plato has shown: (I) that the ordinary moral judgments of men derive their force from the universal 'ideas' or principles underlying them; (2) that all moral judgments without exception presuppose the 'idea of the Good,' which is the real object of every desire. In the Symposium, the Phaedo, and the Republic, he takes a bolder flight and applies his theory of ideas to the universe as a whole. Just as 'the Good' is the supreme principle of human action, so, as we must suppose, the various principles by which the different spheres of reality other than that of human conduct are characterized, must also fall under the same principle. Thus, we reach the conception of a principle of principles. At the same time, Plato is not prepared to admit that this principles completely realized in the particular; on the contrary, he regards it as one of the defects of 'opinion' that it confuses the actual with the ideal, attributing to the former what is true only of the latter; as when it says, "This flower is beautiful," "That act is just," not observing that no object of our experience is perfectly ‘beautiful' or perfectly 'just.' Thus, as it would seem, there is a contrast between the actual, as manifold, changing, and transient, and the ideal, as one, unchanging, and eternal, a contrast which clings to Plato's doctrine to the end, and prevents him from admitting that "the actual is rational and the rational actual." But, while he shrinks from this final identification, Plato insists that there must be a regular ascent from proximate to higher principles, and that nothing short of the reference of these to a single self-sufficient principle can give final satisfaction. Applying this method in the Republic, he seeks to show that the principles of the special sciences, while they are adequate as the standard of the particular phase of reality to which they apply, are not self-sufficient, and therefore presuppose the supreme principle of the Good, or God, which he now conceives as the source of all truth and reality.
So far Plato has been mainly occupied in the endeavor to prove that special phases of the actual presuppose certain characteristic principles, while these must all be referred to a single supreme principle; but, having reached this point, he feels the necessity of showing that these principles are not mere abstractions, but actually explain the particulars to which they are applied. Thesis the problem to which he devotes special attention in the Theaetetus, the Sophist, and the Parmenides. The hurried account just given of the development of his thought may help us to interpret with some degree of confidence the contents of the first of these dialogues, that with which we are more immediately concerned. The problem in which Plato was mainly interested is indicated by what he tells us himself: dissatisfied at once with the Eleatic doctrine, which denied all motion and change, and with the counter-theory of the Heraclitans that nothing is permanent and unchanging, he sought to find a way of escape from the opposite inadequacies of both.1 The first half of this problem is discussed in the Theaetetus, the second in the Sophist and Parmenides. Ianthe special theory of Protagoras, apart from its kinship to the followers of Heraclitus, especially Crotyls, Plato is not interested, mainly because its author had no proper comprehension of theological consequences of his own doctrine. What he therefore does is to bring out the ambiguity in the saying of Protagoras, refusing to allow him to escape under a cloud of rhetoric, effective and useful enough in practical life, but speculatively disastrous, because fitted to confirm the natural tendency of the ordinary man to take his ideas on trust.
Protagoras, as it is implied, did not limit his formula to the sensation of the moment, but said without reservation that, when any judgment is made by this or that individual, it 'appears' to him true, and indeed 'is' the only truth of which he is capable. For Plato, after pointing out the contradiction involved in the general proposition, that every opinion of every individual is true, goes onto say, that "there is more difficulty in proving that states of feeling, which are present to a man, and out of which arise sensations and opinions in accordance with them, are also untrue." What Protagoras actually held, then, if we are to believe Plato, was, that judgments in general, including other, and especially moral, judgments along with judgments of perception, are true only for the individual who makes them, while he drew no distinction between judgments of perception and other judgments, or between judgments of perception and the immediate feeling of a sensitive subject (such as, say, 'feeling hot' or 'cold'). Protagoras, therefore, cannot have distinguished what he said was, that each man must decide for himself what is true or false; so that what 'appears’ true to him, what he 'thinks' to be true, what he 'feels' to be true, is the only ' truth ' of which he is capable. It is thus legitimate to say that Protagoras denied the possibility of arriving at the ultimate truth of things, or, what is the same thing, that he refused to admit the existence of absolutely universal judgments. Plato therefore subjects to close examination the doctrine that all judgments are particular, with its corollary that man is incapable of any knowledge of permanent reality. No doubt Protagoras, in a loose way, was thinking of average good opinion as having superior claims to truth; but Plato was justified impressing home the consequences of his doctrine, on the groundhog it virtually denied any distinction in kind between one man’s judgment and another's, and thus contradicted itself.
How, then, does Plato connect the saying of Protagoras with the definition of knowledge suggested by Theaetetus? The latter he takes as equivalent to the view that each man comes inContact with reality solely through his perceptions. As in the case of Protagoras, no explicit distinction is in the first instance made between the 'feeling' of the individual and the 'judgment ‘based on it; the point of view is that of common sense, which assumes that a sensible object is simply and directly apprehended by the senses. Protagoras and Theaetetus therefore agree in making no distinction between 'feeling' and 'judgment.' And, though Theaetetus is made to identify knowledge with sensible perception, no doubt all that Plato means is, that, as the ordinary man regards sensible things as immediately apprehended, and therefore, never questions their reality, he naturally takes sensible perception as showing what knowledge is; impressed, he will not deny that there is knowledge of what is not directly perceived, but he is sure to add, that perception at least is knowledge.
Now, it is of course Plato's object to show that Protagoras’s view, which practically amounts to saying that there is no criterion of truth but the individual's conviction, or belief, or inability to think otherwise, is untenable. In order to do so, he therefore limits it, in the first instance, to judgments of perception; and thus, he is able to connect it with the view expressed by Theaetetus, that knowledge is sensible perception. When he has brought to light the difficulties involved in this interpretation of Protagoras’s saying, he then goes on to show that even greater difficulties arise from extending it to all 'opinions' whatever. Plato's reference to the Protagorean saying is, therefore, a sort of literary device by which he exhibits the defect of ordinary uncritical opinion. The 'plain man ‘is not aware that, in assuming the truth of his judgments about sensible objects, on the ground of an assumed immediate apprehension, he is virtually affirming that the perceptions of every individual are true; while Protagoras has got so fares to see that immediate perceptions are not always self-consistent, and that, if he claims authority for his own perceptions, he must be ready to concede the same privilege to others.
No sooner has he interpreted the view of Protagoras in the way just indicated, than Plato goes on to connect it with the Heraclitic doctrine that " all things are in flux." In common with all the earlier thinkers except the Eleatics, as he reminds us, Heraclitus maintained that, as all things are in process, we cannot, strictly speaking, say that things ‘are,' but only that they 'become'; for nothing can be found that persists unchanged in two successive moments. That Protagoras sought to justify his own view by reference to this Heraclitic doctrine is not asserted by Plato; but it is obvious that, as he certainly affirmed the immediate truth of the judgments of the individual, especially those directly based upon the perceptions of sense, he could not consistently admit the truth of the Eleatic doctrine, that reality can only be grasped by reason, and therefore, he did not accept the doctrine that all true Beings in itself permanent and unchangeable. As a pragmatist before pragmatism, Protagoras was not the man to trouble himself overmuch with speculations about the ultimate nature of things. It seemed plain to him that things do change; and the proper course for a sensible man, as he did not doubt, was to act according to the view suggested by his personal experience. But, while the doctrines of Protagoras and Heraclitus are cognate, Plato does not say that Protagoras himself connected the one with the other; on the contrary, he makes it clear that the connection was only made by his followers.1 It is their doctrine, therefore, to which Plato refers as a subtle combination of the Heraclitic principle that "all is becoming" with the Protagorean theory of the sensible.
Plato's criticism of this developed Protagoreans assumes throughout, as he was entitled to assume, that whatever is known about reality must be derived from what directly presents itself to the individual. The Eleatic conception of a reality which is different from what appears to each of us is therefore excluded. There is nothing in our experience, as it is argued, to guarantee the unchangeable reality of anything whatever, and therefore we cannot say that things have a fixed and unchangeable character. 1 If this is admitted, we can understand how it comes about that the perceptions of the individual are continually changing. The qualities which we ascribe to a thing, and supposed to be unalterable, are really the momentary appearances which the thing presents to each of us when it is brought into relation to our senses, which themselves are subject to incessant change. Obviously, therefore, each individual will regard as true, and rightly regard as true, what presents itself to him at the moment of his perception; and, if any other person claims to have a different perception of the same object, he will been no way disturbed, but will answer: “Certainly, because you are speaking of the object as relative to your senses; I am speaking of it as relative to mine." It must also be pointed out, that our judgments are by no means adequate to the subtlety of nature. The incessant fluctuation in our perceptions is due to the coincidence of the 'sensible' and ‘sensible perception,’ the 'active' and the 'passive ‘factors, and as there is an infinity of possible combinations, we are able to give distinctive names only to a few of the most obvious characteristics. The conclusion, then, to which we are led is that truth is what appears true to each individual at a given moment, and that, as a necessary consequence, there is no possibility of falsehood.
The doctrine thus elaborated, and referred by Plato to the followers of Protagoras, is substantially the same as that which is now commended to us in the name of 'pragmatism,' 'humanism,' or 'radical empiricism'; and it is therefore of great interest to see how it is dealt with by the first great idealist. Plato was quite aware that it went far beyond the simple doctrine of Protagoras, and therefore, he gives a restatement of that doctrine, unencumbered by the subtleties introduced by his Heraclitic followers. His object in doing so, as I think, was not to throw contempt upon these more recent developments, but to clear the ground for fresh attack upon the whole principle, by bringing to light the unwarranted assumptions implicit in it. The Apologia which he supposes Protagoras to make is briefly as follows: It is certainly true that " our sensations are relative and individual," and, as a logical consequence, that what 'appears' to the individual 'is.' But, while this is undeniable, "one man may be a thousand times better than another in proportion as different things ‘are' and 'appear' to him." It is not denied that "wisdom and the wiseman exist; the wise man is he who makes the evils which ‘appear' and 'are' to a man, into goods which 'are' and appear ‘to him."
The defense of Protagoras, then, consists (I) in reaffirming the main thesis, that truth is for each man what appears to him, and(2) in distinguishing between individuals, not on the ground that one man is capable of truth and another not, but because certain opinions, from the character of their content, ‘work' better or are more conducive to a higher and happier life.
In restating the doctrine of Protagoras, Plato has removed the restriction under which he had so far been viewing it: what is now affirmed is that all judgments, and not merely judgments of perception, are true for each man. Now, one of these judgments is Protagoras' own doctrine, that for each man his own opinions are true; a doctrine which he sets forth as the 'truth,' and which he therefore virtually claims to be of universal application. But, argues Plato, he must admit that men do not usually believe all opinions to be true, and in fact regard such a doctrine as absurd; and, therefore, he is bound to admit that his doctrine, that ever inconclusive, because Protagoras need not grant that the opinion of another is binding upon himself. This retort, however, obviously has force only if Protagoras makes no claim to speak for anyone but himself; a position which he can adopt only at the expense of making his own doctrine meaningless. It is not self-contradictory for an opponent, who admits the possibility of objectively true judgments, to deny the truth of Protagoras's view; but it is self-contradictory for Protagoras, who denies all universal judgments, to advance a doctrine which assumes the universality of his own judgment. It thus seems to me that Plato hasher put his finger on the weak spot of all individualistic views of truth. The individualist must assume at least that his doctrine has a universal meaning; and, if he attempts to limit it by saying that it has no meaning except for himself, he obviously lays himself open to the reply that such a view denies that his judgment has a meaning even for himself. The criticism, as it seems to me, applies to every possible form of individualism, even to that which takes refuge in the supposed limitation of knowledge in general to what is true for man, as distinguished from other possible intelligences. There is no way of proving the absolute relativity of knowledge, for the simple reason that the doctrine that knowledge is absolutely relative must be either universally valid, and snoot relative, or it is utterly meaningless. After showing the untenability of the doctrine of Protagoras, taken in its most comprehensive sense, Plato goes on to consider whether it may not be true when restricted to immediate impressions of sense.
"There are many ways," says Socrates, "in which the doctrine that every opinion of every man is true may be refuted; but there is more difficulty in proving that states of feeling, which are present to a man, and out of which arise sensations or opinions in accordance with them, are also untrue." 1 In this connection Plato recurs to the doctrine of the Heraclitans, which he contrasts with the opposite doctrine of the Eleatics, that the real is unchangeable. We must ask which of them speaks more truly; and " if we find that neither of them has anything reasonable today, we shall be absurd enough to imagine that our own poor opinion may have something in it."
Is it possible, then, to explain the judgments of perception of each man on the basis of the flux of all things? Such judgments must rest upon the immediate feelings or impressions of the individual. Now, if these are in continual process, coming to be and ceasing to be from moment to moment, they afford nothing to which a name may be attached. On such evanescent and vanishing feelings no judgment of any kind can be based; and, therefore, knowledge cannot be identical with perception. In truth, non judgment whatever is possible without the presence in the flux of feeling of a unifying principle, which apprehends the sensible qualities of objects and grasps their likeness and unlikeness, their identity and difference.
"There is, therefore, no knowledge in the impressions of sense, but only in the discourse of reason in regard to them." Thus, as we must conclude, the Heraclitic reduction of reality to pure change and the Protagorean reduction of knowledge to particular judgments are equally irrational. Just as the real must be a permanent which is compatible with change, so knowledge must be a universal which comprehends the particular.
To this hurried summary of the Theaetetus space will only permit me to add a single word. It seems to me of great importance that any theory of knowledge which is proposed for our acceptance should be tested in the most rigid way. There is very great difficulty, because of the indefinite character of ordinary literary language, in avoiding the pitfalls of vague and loose thinking, on the one hand, and of a cramping literalism, on the other; but these opposite dangers must be faced, if we are to think consistently at all. Now, the proposition that " man is the measure of all things," is one of those large and indefinite statements, which can only lead to confused thinking unless we are careful to make clear to ourselves in which of its various possible senses we propose to understand it. Plato, rightly as I think, held Protagoras to mean that each man must determine for himself what is true, and that there is no fixed constitution of things, or at least none that we can discover, and therefore no universal standard of truth. To this doctrine his main objections are: (I) that it contradicts itself, and (2) that it does not account even for the existence of particular judgments. These objections, as I cannot but think, apply with equal force to the most recent forms of relativism. For, what precisely is meant by saying that our judgments are only relatively true? If there are no absolutely true judgments, what are called relatively true judgments cease to have competitors and become absolute; and if there are absolutely true judgments, contrasted in principle with those which fall within our experience, we expose ourselves to the contradiction of claiming to make the absolutely true judgment that we can make no absolutely true judgments. It is this last point that Plato urges, when he draws attention to the contradiction involved in the doctrine of Protagoras, a doctrine which, on the throne hand, denies all absolute judgments, and, on the other hand, assumes the absoluteness of the judgment implied in his own formula. Plato's second objection, that relativism does not account for any judgment whatsoever, seems to me equally cogent. If a judgment merely connects ideas in an arbitrary way, it is indistinguishable from any other accidental association of ideas; and if it brings ideas into a relation, which in any sense expresses reality, it must that extent be true. A judgment which affirms what has no bearing upon reality cannot be true in any possible sense. Even if it is only put forth as valid within the sphere of human action, it must at least have the truth implied in its being a true statement of what actually obtains in that connection; and it seems to me an obvious contradiction to claim truth in this sense, while affecting to deny the possibility of judgments true in the sense of expressing the real nature of things; unless, indeed, by 'the real nature of things' is meant the fiction of a transcendent and therefore unknowable realm, of which nothing can be said, because of it there is nothing to say.