Plato or Protagoras?

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F. C. S. SCHILLER, M.A., D.Sc.


B. H. BLACKWELL, 50-51 Broad Street
All Rights Reserved


In a somewhat shorter form this Essay was read to the Oxford Philological Society on the 15th November, 1907, and there had the benefit of valuable criticisms from Mr. H. P. Richards, Mr. R. R. Marett and others. I have in consequence been enabled to realize more clearly the divergences from the current theories as to the import of the Theætetus to which my own studies had conducted me. They proved to be more extensive than I had suspected, and to involve some interesting and novel issues both of a literary and of a philosophic character. It seemed a duty, therefore, to render my conclusions accessible to the learned world, to which the problems of Platonic criticism are of perennial interest. But though my primary purpose is to raise a literary question, I have not thought it either right or possible to slur over the philosophic importance of my thesis. For the philosophical significance of the Theætetus has been very strangely misconstrued. It contains no tenable account of knowledge. It contains no refutation of Humanism. It refutes nothing but an extreme, and probably exaggerated or misapprehended, form of sensationalism. Nothing of all this has, apparently, been perceived. Nor, again, has what it does contain been fully recognized. It contains a sweeping repudiation of the senses and the feelings as contributories to the growth of knowledge. It contains a renunciation by Platonic logic of the duty of explaining the individual. It is a glorious monument of the Weltflucht to which Pure Thought finds itself impelled whenever it is taken seriously. And its very patient and subtle researches into the problem of knowledge culminate in the frankest and sublimest confession of failure which adorns the annals of intellectualistic literature. Whether or not, therefore, it is possible to exhume from it the lost teachings of Protagoras, it is clear that in the study of Plato’s great dialogues, and particularly of the Theætetus, lies the master-key to the understanding of the whole intellectualistic position in philosophy.

Oxford, December, 1907.

Plato or Protagoras?[edit]

The fifth century B.C. was not only politically, but also intellectually, the great age of Greece. In the history of thought also it makes an epoch. In it philosophic man for the first time rouses himself from a nightmare of childish guessing and a stupor of helpless wonder at the vast uncomprehended and uncontrolled panorama of external nature. For the first time he consciously realizes that he is the Spectator of it all, that the whole world’s infinite complexity exists in relation to him, and that he has not merely an eye to see but also a mind to devise and a hand to execute, if he but has a spirit to dare, that if he will but strive patiently and resolutely to co-ordinate his powers, he may aspire to control the flux and to divert it into channels conducive to the attainment of his highest ends. To the truth of which man caught his first glimpse then he has never since grown wholly blind again, though its vision has often been obscured by the intoxicants and opiates to the use of which his weakness and his sufferings have degraded him.

This first outburst of Humanism, moreover, was in some respects the greatest of the humanistic eras. For it was the freest and most spontaneous and the least hampered by man-made obstacles. All the later revivals of Humanism have been subsequent to the institution of a learned caste whose academic spirit is always largely occupied with ritual observances for giving his due (and not infrequently a good deal more) to the Demon of Pedantry; and so they have had to live and operate in and upon a more or less unfavourable atmosphere. They could not always succeed in developing their Humanism to the full.

The Humanists of the Renaissance, for example, were doubtless sincere humanists in their intentions. They tried to set man’s spirit free from the crushing armour of Scholastic learning, which had immobilized the medieval sage quite as effectively as his defensive mail had immobilized the medieval knight. But they soon fell lamentably short of their noble design and of the proud name they had assumed. Total humanity cannot be identified with any one of its functions, and so ‘humaner letters’ are neither the ‘whole duty of man’ nor even more than comparatively humane. In Scotland ‘humanity’ was academically reduced to Latin. Hence an impartial judge might soon doubt the superiority of Humanism over the Scholasticism which it supplanted in this very point of pedantry. Pedantry is the poverty of the soul, and like poverty it is always with us, while it is only occasionally that the human spirit rises in revolt against the dust-storms of finely comminuted knowledge with which it buries alive all originality and force.

Unfortunately we have little direct knowledge of this earliest Humanism. Its heroes and martyrs, Protagoras and Socrates, have left us no memorial. It is true that by the irony of history the spiritual heritage of one of them soon became a valuable asset, to be disputed over by the philosophic schools of the fourth century, and that so in the end Socrates has become for history what it suited the interest of the strongest, i.e., of the greatest writer, that he should appear. Plato has made our ‘Socrates’ into an intellectualist like himself. But this is manifestly one-sided. The teaching of the real Socrates must have been such as to inspire not only Plato, but also Xenophon, and Aristippus, and Antisthenes. He cannot, therefore, have been the beau idéal of intellectualistic idealism Plato makes him out to be. In his general attitude towards life he probably came far nearer to the progressive types of his own age than a careless reader would infer from Plato. For Plato has made him into a stalking horse in his campaign against his own professional rivals, the Sophists. The historic Socrates, however, probably got on with Sophists of his time even better than Plato admits in the Protagoras.

This interpretation of Socrates, however, is inferential. For from his own mouth we have not one authentic word. Protagoras was more careful of posterity. He wrote a book, but owing to no fault of his, there has come down to us as certainly authentic nothing but two short sentences, which pierce through the veiling mists of tradition like the glittering summits of the Wetterhorn. What was the line of thought which led up to them, what were the reasonings by which they descended into the souls of men, we can only dimly guess. Unless indeed there is truth in the claim of Plato that he had conquered these virgin peaks and left us a trustworthy description of this perilous ascent.

It is this claim of Plato’s that I propose to examine, and more specifically, the Protagoras Speech in the Theætetus 166-68. The conventional view of this speech, which I propose to contest, is that it is as little authentic in substance as in form, and that in it Plato has tried either to represent current developments of Protagoreanism made by his disciples or to embody his own reflections on the problem of putting a reasonable interpretation on an obscure dictum, and that the decision between these alternatives does not greatly matter, because in either case the Speech is completely refuted in the sequel.

But three weighty reasons may be given for rejecting this view. (1) The somewhat tentative language Plato uses as to the authenticity of the defence undertaken by his ‘Socrates’[1] has of course to be taken quite literally on this theory. It is taken to mean that Plato felt really doubtful as to whether Protagoras would have accepted the developments attributed to him. But it is obviously possible, and indeed more natural, to understand his phrases otherwise. Why should not Plato really have felt doubtful about the success of an attempt to reproduce an authentic line of argument and have known that his success might be impugned? (2) It is simply not true that the argument of the speech is refuted, either in the Theætetus or anywhere else in Plato. (3) The conventional view, lastly, will be found to involve itself in insoluble difficulties of a literary kind. A close examination of the argument will show that if Plato be supposed to be the real author of the Speech, he has regaled us with the fancies of a man of straw but told us nothing about the argument of the real Protagoras. Is it not curious moreover that the argument of the Speech is never really answered? Either, therefore, Plato is made into a dishonest controversialist who suppresses his opponent’s case and substitutes for it figments of his own, or into so incoherent a thinker that he cannot see the scope of an argument he has himself invented.

The alternative theory I venture to suggest will be found to cast no such slur upon the moral and intellectual character of Plato. It credits Plato with an honest desire to state his opponent’s case and assumes merely that he has not fully grasped an alien point of view for the appreciation of which his whole type of mind unfitted him, and which even so he has grasped much better than the generality of intellectualists have done down to the present day. It proceeds therefore from two very reasonable presuppositions, (1) that Plato did know the authentic doctrine of Protagoras, and (2) that he did not know it perfectly. As to the reason, we may please ourselves. He may not have actually possessed the suppressed book of Protagoras on ‘Truth’ and have been forced to rely on incomplete memories of its contents. Or again he may have felt that he had not completely made it out.

The reasonableness, however, of these presuppositions will best appear from an analysis of the ‘Protagoras’ Speech and the reply to it as it stands in Plato. The conclusions I shall try to establish are (I) that the Speech is intended to give, and probably to a large extent succeeds in giving, the authentic argumentation by which Protagoras defended his great discovery of the relativity of the object of knowledge to the subject (so far as Plato understood it), because (II), if it is taken to be a figment of Plato’s the great absurdity results, that Plato did not notice that he was refuting himself, and (III), it contains internal evidence showing that Plato never understood it. (IV) It yields, therefore, trustworthy evidence for the reconstitution of the actual doctrine of the historic Protagoras, and (V) this is confirmed by the fact that it actually contains the solution of the problem with which Plato wrestles vainly in the same dialogue, that of Truth and Error.

It is further clear that these positions are not unconnected. For if the current view that the positions taken up in the Speech are disposed of in the progress of the argument can be shown to be untenable, if it is demonstrable that the arguments of the Speech are neither refuted nor even correctly represented in the sequel, it becomes highly probable that Plato has not understood it aright, and that therefore it is not really of his own invention.


If then the substance of the Speech is not Plato’s, whose is it? Surely Protagoras’s claim to it should take precedence over any other. Attempts have been made to attribute its arguments to Aristippus, on the ground that his is probably the philosophy attacked in the earlier parts of the Theætetus. But if our conception of the real relation of Socrates to the thought of his contemporaries be right, the humanistic strain in Aristippus may well have come down to him from his master Socrates, on whom the spirit of the fifth century was doubtless operative, though Plato has done his utmost to erase all trace thereof from his picture of their common master. Hence an agreement between the doctrines of Protagoras and Aristippus is in no wise inexplicable, nor would it prove that the Speech belonged to the latter.

As for the invention of imaginary Protagoreans against whom Plato is imagined to be so eager to contend as to ignore their master, that surely is too desperate an expedient to be sanctioned by any sane principles of historical criticism. In some cases, as in palliating the clearly deliberate misrepresentation of Plato by Aristotle, such an expedient may commend itself to the timidity of reconcilers reluctant to admit that one great thinker may fail to appreciate another, though in this case we know at least that there was a Platonic School on which to impose the burden Aristotle falsely fastens on to Plato, and though even then the hypothesis does not cover all the facts. But in general a master contends with masters and not with disciples. Moreover, there is no clear evidence that Protagoras had any disciples.[2] His appears to have been one of the rare (but all the sadder) cases in which persecution (like that of the Japanese Christians in the seventeenth century) really achieved its purpose. There is no evidence to show that Protagoras’s book survived the Athenian persecution. The one copy which, it is reasonable to suppose, no persecution could extort, viz., Protagoras’s own, must have perished with him when the ship went down on which he was fleeing from the pious wrath of the Athenians and the fate which subsequently befel Socrates. Hence it is no wonder that nobody seems to know anything about Protagoras’s book, beyond the title and the two dicta, except Plato, and that all the later references to it are plainly based on his account. And it is remarkable that even Plato does not seem to have first-hand verbatim knowledge of it, though we shall see that he must have known a great deal more about it than any one has done since.


If we are willing to accept the Speech as genuine Protagoreanism, we are enabled to fill up a great and mysterious lacuna in our knowledge. As at present advised we know nothing about the context of the Homo Mensura dictum. But obviously it must have had one, or rather two, one psychological, the other logical. No man makes a great discovery without being led to it by a psychic process. No man ventilates what may be taken as a giant paradox, without trying to make it plausible and palatable to his audience. Especially if he is a professional teacher, i.e., a man who has lived all his life under a consciousness that his living depends on the approval of this same audience.

It is utterly shallow, therefore, to regard Protagoras’s dictum as an irresponsible freak of subjectivism. Subjectivism from its nature can never be unreflective, any more than pessimism. Objectivisms and optimisms always are initially unreflective, and frequently remain so to the end. For the necessities of life have severely schooled us to begin by turning outward the eye of the soul, and the last thing that man thinks of, the last thing he discovers, is himself.

It is psychologically certain, therefore, that Protagoras must have had, and must have stated, interesting reasons for his position. But we are in the unsatisfactory position of knowing only his conclusion, and neither its premisses nor its context, and no interpretation of the Theætetus can be adequate which takes no account and has no explanation of this fact.

Can we suppose that Plato was equally unfortunate, equally ignorant of the context and grounds of Protagoras’s dictum? Only if we suppose that he neither possessed, nor had ever read, Protagoras’s book on ‘Truth’; nay, that he had never heard it discussed by those who had read it. But this is extremely improbable. It is indeed just possible that Plato knew no more than we do. It is quite possible that Athenian persecution so successfully suppressed the book that no copy escaped to be perused by Plato. Indeed this is even probable, under the very peculiar circumstances of the catastrophe which ended the career of Greece’s greatest Sophist. We may infer this also from the hesitations and apologies with which Plato always accompanies his account of Protagoras. These become intelligible if we suppose that he possessed no copy of the book himself and was not in a position to cite textually anything but the two admitted dicta.

But it is incredible that Plato should not have been familiar with the substance of the book. It was published, as the crown and outcome of the long career of the most popular teacher of the day, in Athens, Plato’s native city, in 411 (or 412) B.C., when Plato was already well advanced in his teens. If he was then already interested in philosophy, he must surely have read it, or at least have heard it discussed. Even if he was not, he must have been the contemporary of dozens who had read it and of hundreds who had heard it discussed; for in a democracy, which cannot act with a tyrant’s promptitude, some time would elapse before the indignation of the orthodox could gather force enough to lead to its denunciation and destruction, and the withdrawal of Protagoras from the city. Plato, therefore, was in a position to ascertain the real arguments of Protagoras with great exactitude. For it is improbable that they were protected from reproduction by their abstruseness. Protagoras was not a recluse like Heraclitus, but a popular lecturer. His arguments cannot have been too subtle to be committed to memory.

But if Plato knew, not indeed textually but in substance, the arguments which Protagoras had advanced for his position, why on earth should he suppress them? Why should he not reproduce in his polemic such of them at least as he thought he could answer? Why be at pains to invent bogus arguments on behalf of Protagoras, when the genuine ones were extant, and might even be remembered by the seniors in his own audience? Surely it would have been neither artistic, nor honest, nor prudent, to attempt more than to re-word in a condensed form the substance of the genuine argument. And this is precisely what the Theætetus indicates throughout. The remark in 171 E, which is the chief ground for attributing to Plato the complete fabrication of the Protagoras Speech, does not imply more than this, if it is not unfairly pressed.


If Plato had invented the Protagoras Speech, he would surely have made a better job of it polemically. He would have taken care not to put into the mouth of his ‘Protagoras’ anything his ‘Socrates’ did not subsequently refute. If, therefore, there can be found in the Speech arguments which the Theætetus does not refute, we may be sure that they were not of Plato’s invention. And if Plato thinks he has refuted them and it can be shown that he is wrong, this confidence will be strengthened; there will remain no reasonable doubt but that he has tried in his Speech to represent a real opponent’s actual views, that he has failed to understand him, and therefore failed to dispose of him, as he supposes.

An unprejudiced reading of the Protagoras Speech will, I believe, bear out all these contentions.

The Speech falls into three parts. (1) 166 A—C, (2) 166 D—167 D, and (3) 167 D—168 B. (1) ‘Protagoras’ begins with a protest against the verbalism of the ‘Socratic’ contentions that have preceded. The memory of a perception must not be lumped together with the perception. It is in no wise absurd that the same person should know and not know the same thing—at least, we must add, if as in Plato’s examples (165, etc.) the thing is taken in a different reference. As for the difficulty of the change in the knower which results from his interaction with the object, we can, if you insist that he cannot be identical in change, regard him as an infinite plurality.[3] ‘No’, says Protagoras, ‘face the real point: deny outright that we have peculiar and individual perceptions, which we alone experience.’

In part (2) he expounds his true doctrine and refutes the misinterpretations put upon it. ‘While I affirm that each man is the measure of what is “true” for him, I do not deny that one man may be 10,000 times as good as another, in this very point of what appears to him and is to him “true”. It is thus that the wise man is distinguished from the fool; he is one who is able, when things appear to us and are bad, to make them appear and be good.’ [I.e., who teaches us how to make the best of a bad job and to adjust ourselves to life.] ‘Your own illustration of the sick man to whom what is sweet to the healthy seems bitter tells against you, Socrates. It is futile to make either of them any “wiser” than they are, or to declare that the sick man is uninstructed in judging as he does: what he needs is to be altered; for the contrary condition is the better. Thus the sophist’s task is practical like the doctor’s; but his ministrations use words, instead of drugs, to produce a better state of mind. There is no question, therefore, of turning “false” opinions into “true”; all we opine is always “true” in so far as it expresses what we experience. But whereas a soul in bad condition opines badly, a good one produces good thoughts. Some mistakenly call such “better” appearances “truer,” but I merely “better” or “worse” but not “truer”. Wise men, therefore, are they who, like the physicians of bodies, or the cultivators of plants, train men to perceive aright. And the sage or ‘sophist’ performs a similar service also for cities; wherefore he earns his pay.

‘(3) We see, therefore, that in a sense, though no one can be said to opine falsely, some are wiser than others.’ The Speech concludes with a grave admonition to ‘Socrates’ to cease from arguing disputatiously, and points out the harm this does by disgusting people with philosophy, and the perils of arguing from the current usage of words which only lead to puzzles.


In its whole tone and contents this Speech seems to me exactly what we should expect from an attempt at authentic reproduction. The anti-intellectualism, the emphasis on the practical side, the defence of pay for intellectual work, the didactic tone, the high moral seriousness (which Plato attests also in the Protagoras), the disgust with the endless and often aimless ‘dialectics’ of the Greek boulevardier, the consciousness of the dangers of verbal traps, these are all characteristics we might expect to find in the veteran teacher whose mission it was to guide the education of a democratic age.

Why then should we hesitate to attribute to him also what is the cardinal point of his defence, viz., the distinction between the formal claim to truth which every judgment makes and its value? This point is made lucidly, repeatedly and emphatically, and if my paraphrase has brought it out still more, the reason is merely that, thanks to Plato, most philosophers have become involved in so dense an intellectualistic bias that anything which runs counter to it has to be made very clear indeed. But the distinction is quite clearly in the Greek.

It is also quite clearly the complete answer to the attacks on the humanism, miscalled the ‘subjectivism,’ of Protagoras, and the solution of the problem of a common truth. It explains how we pass from individual claims to social values, and attribute to them an objective validity. The bricks out of which the temple of Truth is built are the individual judgments which supply the material. Every one is continually making them. But of these a large proportion are half-baked, or broken, or of the wrong shapes. So these have to be rejected. They may still seem to their makers subjectively ‘true,’ but they are objectively useless. Whoever, on the other hand, has the skill to devise a form of brick which is useful finds hosts of imitators. He becomes an architectonic authority, and is called in to mould or re-mould the bricks of others. And so dominant patterns arise which prevail and attain an objective validity. But this validity is the reward of value and the result of selections based on experience. The ‘validity’ of a claim to truth is neither logically nor etymologically other than its ‘strength.’ There is no need to presuppose any inaccessible supercelestial archetype which ratifies and sanctifies by a suprasensible communion, the human imitations we inexplicably make. Still less do we need any deus ex machina supernaturally to establish by his fiat any initial ‘commonness’ of truth. We do not even need any ‘independent’ object magically authenticating its ‘true copy’ in our thoughts.[4] All we need is that there should be de facto differences in the value, and therefore in the subsequent validity, of different people’s judgments. And of these we have, of course, abundance.

It is noticeable, however, that Protagoras is represented as declining to call these superior values ‘truths’. They are ‘better’ but not ‘truer’. If so, he did not yet perceive that all ‘truths’ are ‘values,’ and therefore ‘goods,’ even though an individual’s truths are good and satisfying only to him, and their value is very restricted, because their currency is small. Nor again can he have seen that the same ambiguity which pervades truth-values pervades also all the rest. Many things are judged ‘good,’ which are not really good, just as they are judged ‘true’ without being really true. Everywhere there is needed a bridge of validation by use to cross the gap between claim and validity. But it is also possible either that Plato has not here reproduced the full subtlety of Protagoras’s argument, or that Protagoras was hindered from expressing himself fully only by the poverty of Greek philosophic language, not yet enriched by the genius of Plato. Anyhow, the difference between Protagorean and modern Humanism concerns only a subordinate point of terminology.[5]

What now, we may proceed to inquire, does Plato make of this important philosophic distinction he has attributed to Protagoras? It is astounding to find that he makes nothing of it whatsoever. He treats it almost as badly as the other three un-Platonic points made in the Protagoras Speech, (1) the repudiation of intellectualism and of the doctrine that badness is simply ignorance (166 E—167 A), (2) the demand for an alteration of reality by practical action and not by dialectics (166 D and 168 A), and (3) the declaration that the State may err morally like the individual, and may need the services of the moral expert (168 B). These three points the Platonic ‘Socrates’ totally ignores in the sequel.

The conception of truth-values he just refers to, but his reference to it is worse than none at all. For it only shows that Plato had no conception of the meaning and scope of the argument he had just stated. In 169 D, he starts again from the bare dictum as if the Speech had done nothing to explain its real meaning nor given it a philosophic context. And the reasons ‘Protagoras’ had given for the dictum are actually treated as concessions derogating from its validity and inconsistent with his original assertion! Nothing could be more unfair and unenlightened, or even more contrary to the very wording of the Speech. For in the Speech ‘Protagoras’ emphatically puts his doctrine forward as his very own, and distinguishes it from the laxer use of popular language, (167 B[6]). And well he might; for it is the vindication, not only of his whole career as a skilled adviser and educator, but of the liberty which he concedes to every one to hold by his own experience. Such a profound misconstruction seems possible only in one who was reproducing with imperfect success an argument he did not understand.

There follows immediately afterwards a still more extraordinary proof of the discomfort which the Protagorean mode of thought had occasioned in Plato’s mind. For in 169 E, it is suggested that as Protagoras is not present to confirm the ‘concessions’ made on his behalf, it will perhaps be better to restrict the discussion to his own words, the original dictum!

By this master-stroke of dialectical manipulation the whole defence of Protagoras is declared invalid and set aside, and we are once more reduced to the bare dictum and stripped of all knowledge of what it really meant in its context. This procedure is so arbitrary that even Plato’s literary art cannot quite reconcile his readers to it. But on our hypothesis it is at least intelligible. On the hypothesis that Plato has concocted the Protagoras Speech it becomes utterly unthinkable. For how can one believe that, after propounding a defence of Protagoras which was at least novel and striking even if it was not completely adequate, Plato should at once have dropped it, merely because he suddenly felt a conscientious qualm lest Protagoras himself should not have approved of it? Surely whether the argument of the Speech was Protagoras’s or Plato’s, once it was stated, it should have been answered, and in the latter case at least it could have been answered: the presumption, therefore, is that Plato dispensed himself from this duty because he perceived that it surpassed his powers. For it is worth noting that though the Speech is evicted, it is never refuted. Its points are almost ostentatiously ignored henceforth, but no attempt is made to answer any one of them, and the argument becomes almost farcical in its unfairness. The logical value, therefore, of the ensuing argument is slight.

For example, (1) in 170 A Socrates insists on treating the difference between the authority and the fool as merely one in knowledge, despite the protest in 167 A, against this very trick of intellectualism. Protagoras having denied that differences in truth-value were merely intellectual, Plato makes a point of reaffirming his intellectualist analysis dogmatically and in the very same words. The protest of the Speech, therefore, has been wholly vain.

(2) So, too, were the protest against relying too much on popular language and the explanation of the apparently unfamiliar assertion that all always judge ‘truly’. For as 170 C shows, Plato continues to base his objections on the current use of the words ‘true’ and ‘false’.

(3) The argument in 170 D, which seems a clincher to Plato, is almost ludicrously inconclusive to one who has grasped the manifest meaning of the Protagoras Speech. It is in no wise absurd that an opinion (which you may roughly call ‘the same’) should be ‘true’ to me and ‘false’ to you; nor that one man should be right and 10,000 wrong.

For (a) it may well be ‘true’ to a lover that his mistress is the most beauteous creature in the world; but it by no means follows that this is ‘true’ to the rest of the world, nor is it even desirable that it should be. If then it is true that there is a peculiar and personal side to every piece of knowledge, he who has the experience alone can judge of its value. He alone feels where the shoe pinches or sees the subjective glow which transfigures the landscape. (b) Even where we feel entitled to abstract sufficiently from this individuality of concrete experiences to speak of a ‘common’ situation, it may be perfectly legitimate for different minds to evaluate it differently. All views may be right from their several standpoints, and they generally are so more or less. To deny that the ‘true’ mode of attaining the Good varies according to the circumstances of the agent is both intolerance and ineptitude, (c) Athanasius contra mundum and the fact that all new truth necessarily starts in a minority of one, should moderate our reliance on numbers as a test of truth. ‘Universal consensus’ is a consequence and not a cause of truth.

(4) It is in vain, therefore, that Plato attempts (in 170 E—171 C) to show that on his own principles Protagoras must bow to the verdict of the majority who reject his dictum. Plato’s argument here is completely vitiated by the ‘ambiguity of truth,’[7] and as it completely ignores the distinction made by the Protagoras Speech, it is a mere ignoratio elenchi. For ‘Protagoras’ has already explained how on his theory scientific authority was constituted. He could, therefore, reply—‘My dictum may be “true” (claim) for me, even though it is not “true” for all the world besides. There is no contradiction in this, for we are different. I am Protagoras: you, to put it mildly, are—not! And I may already be right, though no one else perceives it yet. For eventually men may come to see that my view is really “better”. And then the validity of the truth I now claim will be admitted.’

(5) In 171 E—172 C Plato propounds a restriction of the dictum’s claim to matters of sense-perception, exempting matters of health and disease from its sway, and he identifies this restricted claim with the position of the Protagoras Speech.

This passage, ᾑ ἡμεῖς ὑπεγράψαμεν βοηθοῦντες Πρωταγόρᾳ, which has already been referred to (p. 14), at first sight seems direct evidence in favour of the view that the Speech is really a Platonic invention, and if this were the only or the best interpretation of the remark, it would be almost fatal to the contention of this study. But in point of fact it may be shown that it is only part of Plato’s misconstruction of the Speech, and that upon examination it tells strongly in favour of the view that the Speech is genuinely Protagorean and has been utterly misunderstood by Plato. To put the matter quite bluntly, it is not true that the Speech said what Plato’s ‘Socrates’ now says it said. The discrepancies between what was said and what is now alleged may doubtless look small, but they are not insignificant; and it is obvious that nothing very glaring could be expected. For if Plato had become aware of any considerable divergence between the text of the Speech and his subsequent version of it, he would have modified one or the other.

(a) The assertion that the restriction now proposed is a concession to common-sense on the part of Protagoreanism is merely a repetition of the remark in 169 D. It does not become more plausible thereby. And it has already been explained how profound a misconception of the chief distinction made in the Speech is implied in this assertion.

(b) Nothing is said in the Speech about a division of territories whereby the sphere of perception would be left to the dictum, while that of good and evil, and of health and disease would be assigned to the control of authority. The contention of the Speech was that of judgments equally true one might be better than another. And this was laid down universally. Neither subjectivity nor valuation was confined to sense-perceptions, thus implicitly giving the lie to Plato’s attempt to fuse the humanism of Protagoras with the sensationalism of his day, an attempt the arbitrary nature of which is as good as confessed in ‘Socrates’s’ remark in 152 C, that he is divulging a ‘secret doctrine’ to an astonished world. No restriction, therefore, of the personal implication in all knowing to the sphere of mere perception can for a moment be entertained by any logical Protagoreanism, and this implication must carry the universality of valuations with it. If e.g., I am short-sighted and you are not, your visual perceptions will be ‘better’ than mine. But this will not make them ‘true’ to me. The fact that you can read print at a distance impossible to me, does not enable me to do so, though the manifest superiority of your practical adjustments will induce me to admit and to envy the superiority of your perceptions. I shall continue to see a blur, where you see clearly, as before. It would seem, therefore, that in attempting to apply the distinction of the Speech, Plato has restricted it in a way which the Speech does not warrant and the facts refute. Surely a curious fact on the hypothesis that he was himself the author of the distinction!

(c) Plato’s quotation of the words of the Speech is seriously inaccurate. He substitutes ‘healthful’ and ‘diseased,’ for ‘better’ and ‘worse’. But in the Speech these were merely illustrations of the general principle, and the distinction was not restricted to them.

(d) The argument about the cities in 172 A—B is both inaccurate and absurd. Nothing was said in the Speech about the ‘advantageous;’ the terms used were ‘good’ and ‘evil’. Moreover, the compromise proposed is impossible, as Plato must have been fully aware. You cannot allow States to judge as they please about the just and the moral, if they are to be controlled by a perception of their true advantage. For their ideas about justice also may chance to be extremely disadvantageous to them, and may therefore require to be altered. The ‘Protagoras’ of the Speech had talked no such nonsense: he had very sensibly and truly remarked that the opinions of States about the just might have to be altered, just as those of the sick man about the sweet.

In short, Plato’s references do not exactly reproduce either the words or the sense of the ‘Protagoras’ Speech, and thereby prove pretty conclusively that he was not the real author of its contentions. For those who insist on believing that he was, his whole handling of the Speech must seem an unfathomable mystery. He first contrives this brilliant Speech, which contains a number of points, new and unheard of in all Platonic philosophy, together with one distinction of capital importance. And then he goes on as if he did not know what he had done, as if nothing had happened! The main point is blankly ignored, the references to the Speech are all curiously vague and inexact, and the whole Speech is almost at once set aside as possibly inaccurate, on an absurd pretext that the wording is not by Protagoras. If this was the way in which he was going to treat it, why did Plato trouble to make a statement he could make so little of? The Theætetus would have been gayer and more forceful without a long, halting and impotent discussion of what seems a half-understood position. Nothing but external compulsion would drive an expert controversialist to such shifts. But may not such compulsion have been forthcoming from the expectations of his older readers, who remembered the actual reasonings of Protagoras and required of Plato an attempt to meet them?

And the philosopher must urge this difficulty still more insistently than the literary critic. The Theætetus contains a position of immense philosophic importance, whether it originated with Protagoras or with Plato. It is never dealt with. Why not? And is not the philosopher seriously concerned to estimate how much it detracts from the security of Plato’s chosen creed to have left a hostile stronghold, however weakly garrisoned, untaken, nay unassailed, in his rear?

(6) When after a long digression, in the course of which Plato emphasizes the hopeless transcendence of the truly real and valuable with the utmost acerbity, the argument is resumed in 177 C, Plato first, quite superfluously, proves what the Protagoras of the Speech had long ago pointed out, viz., that cities often do not know their own advantage.

(7) In 178 A a fresh point is made. Can it be maintained that each man is the measure not only of his present perception, but also of the future? Will that be exactly as he anticipates? And does not the knowledge of the advantageous depend mainly on the future?

The Platonic ‘Socrates’ appears finally to rest his case on this point and on the argument in 171 C [our No. (4)], by which Protagoras was alleged to refute himself. In reality, however, the appeal to the future leads to a triumphant vindication of the Humanist interpretation. For how does the future decide between two rival theories of truth? By the value of the consequences to which they severally lead. That is precisely the meaning of the pragmatic testing of truth by its consequences. Whether Protagoras would have replied in this way if the point had been brought to his notice, we are not, of course, in a position to say; but enough has probably been said to show that if we read the Theætetus critically and do not credulously swallow every claim Plato chooses to make without verifying it, there can be no question of a refutation of the argument of the Protagoras Speech by the subsequent criticism.


Plato himself, moreover, was a better judge of the value of his argument than his followers, and so was not unaware of the incomplete character of his dialectical victory over the bare dictum of Protagoras. He realizes plainly that in order to justify his rejection of it, it is incumbent on him to devise a tenable theory of Error. For even ‘subjectivism’ cannot be refuted by more scepticism, and even a rationalistic theory of knowledge is bound to discover some difference between ‘truth’ and ‘error’. This implication of his logical position, was not, of course, a thing to make too dangerously prominent, but it is clearly the meaning of the remark in 190 E, that ‘if we cannot show that false opinion is possible, we shall be obliged to admit many absurd things’. The ‘many absurd things’ are the Protagorean view of Truth as it has been interpreted by Plato. And the connexion between it and a failure to solve the problem of Error is this: if the possibility of Error cannot be explained, there can be no ‘false opinion’: and if there can be no ‘false opinion’ then all opinions are true; but this was precisely what Protagoras had meant, according to Plato. Hence the Platonic inquiry is on its own showing in the awkward position of being bound to discover a tenable theory of Error in order to save itself from a relapse into a Protagorean ‘subjectivism,’ which it has itself rashly declared to be equivalent to an abolition of all truth.

Nor does the fact that the Platonic interpretation of Protagoras is wrong, in any way relieve the logical pressure upon Plato’s intellectualism at this point. For as an ad hominem refutation, a failure to devise a theory of Error tells against Plato’s theory in any case. Whether or not Protagoras had really denied the possibility of Error, Plato’s theory of knowledge must irremediably collapse, if it cannot account for the existence of Error. And, unlike many modern intellectualists, who seem to contemplate with equanimity their total failure to discriminate between truth and error and to regard it as quite an unimportant defect in a theory of knowledge, Plato saw this clearly.

Hence the zeal and perseverance with which the inquiry is prosecuted. Plato is battling pro aris et focis, to save the central fire of intellectualism from extinction, and it is probably because he realized this as none of his successors have done after him, that he produced his great classical discussion of the problem, which is distinguished by ingenuity and ennobled, though not saved, by the frank confession of final failure.

That this failure was an inevitable outcome of Plato’s presuppositions is the next point for us to understand. We shall in understanding this understand also that no intellectualist theory of Error is possible, and consequently no really adequate intellectualist theory of knowledge. For a theory of knowledge which cannot explain Error cannot discriminate it from Truth, and so cannot explain that either.

With the usual naive objectivism of ancient metaphysicians, Plato starts from the assumption that Error is something objective and inherent in the object of knowledge. I.e., Plato has made the usual abstraction from the human and personal side of knowledge and assumed that this can have no bearing on the theory of logic. If, therefore, this assumption is wrong, we can at once account for the failure of his efforts, without being driven into the scepticism, in which intellectualist epistemologies invariably end.

But to be more specific, if the possibility of Error is dependent on the nature of the object, there must be an object of error as well as an object of knowledge, and the error must consist in our taking the one for the other, or getting the one when we want the other. To know this, however, we must necessarily know both. We must know, that is, the object of error as such, and to do this would of course be not error, but truth. For we should ‘apprehend it as it is’. Again, in so far as an object of knowledge is involved in error recognised as such, it is known truly. Error, therefore, always involves the contradiction that we must simultaneously both know and not know in the same cognitive reference. Thus a theory of Error is unthinkable. The same conclusion follows if we start from any formal view of Truth. For we thereby incapacitate ourselves for distinguishing between a truth and a claim to truth, and as the latter may be wrong, error becomes a kind of truth and we are, once more, unable to distinguish between truth and error.

Such in essence is the impasse to which all Plato’s ingenious speculations in the end conducted him. He could not find the real clue to the maze, because of his initial abstractions. Having abstracted from the personal maker of the judgment, he never noticed that errors do not exist as such until they are found out. A false judgment is in form indistinguishable from a true one, a self-contradictory judgment being unmeaning as expressed. Hence in dealing with errors no man can ever be simultaneously in a condition of both knowing and not knowing. While we maintain the ‘error,’ we judge it to be ‘true’; when we have discovered it to be an ‘error,’ we no longer affirm it. As critics we can of course perceive errors which others judge to be true. Indeed, the ‘errors’ that trouble us are generally not our own, but those of others, which they affirm and we deny. But when the traditional ‘logic,’ after tabooing all systematic reference to the psychological context of its subject-matter, proceeds to treat of Error in the abstract, it declines to look beyond the fact that ‘the same’ proposition is both affirmed and denied, both known and not known. I.e., it has abstracted from this difference in the persons who affirm and reject the erroneous judgment. But this difference is essential, because it may always affect and dissolve the unity of what has been called ‘the same’. Hence ‘logic’ has debarred itself from all intelligible treatment of the question.

The second point to be grasped is that the seat of Error is not in any defective configuration of the ‘object,’ but in its relation to a cognitive purpose. That some errors consist in the affirmation of non-existent objects is not only unimportant, but wholly irrelevant. It is irrelevant because it involves a confusion of an ontological with a logical ‘object’. The logical ‘object’ is never non-existent, even though we may be discussing Centaurs, Chimaeras, Absolutes, intellectualistic theories of knowledge and other ontological nonentities. But all errors denote the defeat of a cognitive purpose. Hence the failure of a purposive thought to attain the aim or ‘object’ which would have satisfied it, can never be treated in abstraction from the personal aspect of knowing. It cannot be described per se or be represented in merely formal (and therefore verbal) terms. It always implies a relation to something beyond the two ends of the proposition. It is nothing intrinsic in the judgment, it is never to be judged as a purely intellectual thing.

How, on the other hand, does this problem look if we approach it from the aspect of knowledge for the first time seen and emphasized by Protagoras? It will be found that this much-maligned and little understood theory has no difficulty in coping with it. For it starts with human knowing, not with ‘ideals’ of a ‘perfect’ knowledge inaccessible to man. Every judgment is a claim to ‘truth,’ i.e., an experiment with ‘reality’ as it appears to us. But such experiments may fail as well as prosper. If they succeed, we recognize their value and hail them ‘true’. If they fail, wholly or in part, we condemn as ‘false,’ and admitting that we were ‘wrong,’ withdraw the values claimed. Gradually in the course of time there are thus segregated two great realms, of light and darkness, Truth and Error. But between the two will lie much disputed territory, where, either because our experience is not yet adequate or because our experiments have not been decisive, there is ample room for doubt and difference of opinion.

But only a mind thoroughly corrupted with dialectic and corroded with scepticism will base on its existence a charge that to recognize these facts is to abolish the conception of Truth. In reality we are here on the holy ground where, by the continuous revision of values and the rejection of ‘errors,’ Truth is made, where knowledge is alive and growing. And the fertile soil yields the only sort of truth that has use or meaning for man. You cannot, it is true, raise on it any humanly fruitless and unprofitable crop of Platonic Ideas. If the seeds of such sterilities are scattered on the ground by breezes that issue from the bags of Æolus, they will fail to germinate in a soil so richly manured by the heart’s-blood of human desire and the bones of the martyrs of human science. But our loss is nil; for such static forms would be utterly unsuited to our needs. We need plastic conceptions that can adjust themselves to the dynamic nature of reality, and, in Plato’s parlance, can know the ‘flux.’ It is only in unmeaning tautologies that the ‘ideas’ remain immobile even in the single judgment. In all real knowing subject and predicate always have their meaning changed by being combined in a judgment, alike whether this growth enriches only the mind of a single knower or extends to all those who are interested in the advancement of human knowledge. All our concepts, therefore, as James says, are teleological weapons of the human mind.

Plato, doubtless, would never have admitted that such mere instruments of human knowing were true ‘Ideas’. But neither he nor any of his many followers has ever been able to devise a tenable formula to express the (unthinkable) relation of the plastic ‘Ideas’ we use to the immutable ‘Ideas’ they have vainly postulated. Hence though we may be glad that he has expressed for all time the perfect exemplar of the rationalistic temper, we cannot in these days imitate his superb fidelity to an impracticable ideal. The growth of Science and the application of Knowledge to Life are too stupendous facts to be ignored even in the seclusion of academic lecture-rooms. And so, though philosophers as a body will naturally be the last persons to admit it, it must eventually be recognized that Protagoras’s vision of a Truth that did not shun commerce with man was truer than Plato’s dream of an Eternal Order that transcends all human understanding.


Since the above study was written my attention has been called to an article on Plato and Protagoras in the Philosophical Review, xvi., 469, (September, 1907) by Prof. J. Watson. Its appearance is a welcome sign of the times in so far as it indicates a perception that the old controversy between Protagoras and Plato is by no means dead and recognizes that it turns on essentially the same point as the modern issue between Humanism and Absolutism. But Prof. Watson could have very materially enhanced the timeliness and relevance of his discussion by taking more adequate cognizance of the Neo-Protagorean position. Even if my Studies in Humanism (pp. 33-38, 145-46, and 298-347) appeared too recently to be used by him, he might at least have referred to a quite explicit article which appeared in the Quarterly Review so long ago as January, 1906. Instead of this he confines his polemic to a passing remark in the Preface of my Humanism, the full justification of which is only forthcoming in the present study. It is, however, satisfactory to find that he also thinks that Plato meant to give the veritable views of Protagoras. He holds also that Plato, when writing the Theætetus, had access to the treatise of Protagoras, a position which I have given reasons for thinking not only intrinsically improbable, in view of the apologetic tone of the Platonic reproductions, but also untenable, as ignoring the external authority of Diogenes Laertius, ix., 52. So despite of what I said in Studies in Humanism, p. 37, it now seems to me far more likely that Plato was relying wholly on oral tradition about a work that was no longer extant. The Speech Prof. Watson ascribes to a ‘developed’ Protagoreanism fabricated by Plato himself, without attempting to explain why Plato should proceed to ‘develop’ a doctrine for which he had not yet stated the authentic grounds, and then return to the undeveloped form without refuting its ‘developments’. He says nothing about the relevance of the discussion of Error, and particularly of 190 E, to the issue, and his whole exposition of Plato’s arguments is unfortunately far too general and goes too little into the detail of the text to establish any of his contentions.


  1. 165 E, 168 C, 169 E, 171 E.
  2. Theodorus in the Theætetus is represented (1) as his friend, and (2) as no philosopher but a mathematician. As for the Antimoerus of the Protagoras (315 A) we never hear of him again.
  3. Compare with this James’s analysis of the knower into a succession of momentary I’s, each inheriting and summing up his predecessor. Any dynamic account of knowing will tend to have recourse to such descriptions, in order to combat the useless assumption of a static knower, and will be similarly charged with destroying the knower’s reality.
  4. Lest I should hereabouts be unintelligently charged with denying ‘objective reality’ altogether, I must append a note to this remark. The only sense (out of many) in which a Humanist theory of knowledge does away with ‘independent objects’ is the utterly nugatory one in which the ‘object’ is made so ‘independent’ as to transcend human cognition altogether: all the other senses of ‘objectivity,’ it expounds and explains, each in its proper place. It is most unfortunate that both ‘realists’ and ‘absolute idealists’ should apparently have piqued themselves on, quite irrationally, affirming just this superfluous absurdity, and on tying all the legitimate senses of ‘objectivity’ on to it. Cf. my Studies in Humanism, pp. 439, 461-62.
  5. Cf. Studies in Humanism, p. 36.
  6. ἃ δή τινες τὰ φαντάσματα ὑπὸ ἀπειρίας ἀληθῆ καλοῦσιν ἐγὼ δὲ βελτίω μὲν τὰ ἕτερα τῶν ἑτέρων, ἀληθέστερα δὲ οὐδέν.
  7. As I have shown in Studies in Humanism, pp. 145-46.

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