Protagoras · Philosophy
Condemned by Plato and reduced to a byword for fallacy, Protagoras was rehabilitated by modern thinkers who saw in ‘man is the measure’ a profound anticipation of pragmatism, perspectivism, and the modern critique of objective truth. His relativism became one of the central, contested ideas of modern thought.
For most of the two thousand years after his death, Protagoras existed in the Western imagination only as a defeated opponent - the foil Plato set up in order to knock down, the ‘sophist’ whose very name became a slur. This was not because Protagoras’ ideas had been shown to be worthless, but because his chief expositor was also his chief antagonist, and that antagonist happened to be the most influential philosopher and one of the greatest writers in the entire tradition. Plato’s dialogues - the Protagoras, the Theaetetus, the Gorgias, the Sophist - became canonical texts, read and revered for millennia, and in all of them the sophist is cast as the embodiment of intellectual error and moral danger: the relativist whose doctrine self-destructs, the seller of persuasion indifferent to truth, the dark double of the true philosopher. Protagoras’ own books did not survive; his case was heard only through the mouth of the prosecutor. Small wonder the verdict went against him.
This is one of the most striking examples in intellectual history of how reputations are made and unmade by the accidents of transmission and the talents of one’s enemies. Had Protagoras’ own works survived, or had a defender of comparable genius taken up his cause, the history of the very word ‘sophist’ - and perhaps of relativism itself - might have run quite differently. Instead, for two millennia, to be a ‘sophist’ was to be a clever fraud, and ‘man is the measure’ was remembered chiefly as the doctrine Plato had triumphantly refuted. The rehabilitation of Protagoras - the recovery of the serious thinker behind the Platonic caricature - would have to wait until the modern age, when new philosophical movements arose that found in his ancient relativism not an error to be refuted but an anticipation of their own most cherished insights. The villain of the dialogues was about to become a prophet.
The first great modern rehabilitation of Protagoras came from the pragmatist movement at the turn of the twentieth century, and especially from the English philosopher F. C. S. Schiller, who explicitly took up Protagoras’ banner and even called his own version of pragmatism ‘Humanism,’ in conscious homage to the man-measure doctrine. Schiller and his greater American ally William James found in Protagoras a prophet of their central conviction: that truth is not a fixed correspondence to a ready-made reality but is bound up with human purposes, needs, and experience - that truth is, in some sense, made rather than found, and that the human knower is an active participant in what counts as true, not a passive mirror of an independent world. James’ famous (and much-misunderstood) formula that the true is ‘what works,’ what proves useful and satisfactory in the conduct of life, can be read as a sophisticated descendant of ‘man is the measure’: the standard of truth is brought back, once again, to the human and the experiential.
Schiller pressed the connection openly. ‘Man is the measure of all things,’ he argued, was not the absurdity Plato made it out to be but a deep and defensible insight - that all our knowledge is human knowledge, shaped by human faculties, interests, and ends, and that the dream of a purely objective truth wholly independent of the knower is a chimera. The pragmatists did not, for the most part, embrace the crudest relativism (that any belief is as true as any other); they held a subtler view, that truth is what survives the test of experience and serves human life, which allows beliefs to be better or worse, more or less workable, while still denying a truth utterly detached from human concerns. In this they recovered something of Protagoras’ own subtlety - his ‘better, not truer’ distinction, his focus on what improves human life - and rescued him from the caricature of the man who thought every opinion equally valid. Through the pragmatists, Protagoras was reborn as a forerunner of one of the most influential philosophical movements of the modern age, and ‘man is the measure’ was heard again, after two thousand years, not as a refuted blunder but as a serious claim about the human character of all our truths.
The long afterlife of Protagoras - from Platonic villain to pragmatist prophet to the half-understood slogans of the present day - matters because it shows that the question he raised is not a settled matter of ancient history but one of the permanent, recurring fault-lines of human thought. The quarrel between Protagoras and Plato - between the view that truth is relative to the human measure and the view that there is an objective truth the same for all - has never been resolved, and it re-erupts in every age in new forms. It is there in the modern debates between objectivists and relativists, between realists and constructivists, between those who hold that science describes a mind-independent reality and those who hold that all knowledge is socially or perspectivally conditioned. It is there in disputes about whether morality is universal or culturally relative, about whether there are human rights that hold across all societies or only the norms each community happens to adopt. It is there, in degraded form, in the culture’s casual talk of ‘your truth’ and ‘alternative facts.’ Wherever human beings argue about whether there is a single truth that measures us all or only the many truths of our differing standpoints, they are continuing the argument Protagoras began.
This is the deepest measure of his importance, and it vindicates him against the long centuries of dismissal. Protagoras was not a foolish relativist refuted once and for all by Plato; he was the first to formulate, sharply and seriously, one of the two great permanent options in the theory of truth - and the fact that his option keeps returning, in ever-new guises and ever-more-sophisticated forms, shows that it captures something deep and resistant in our situation as knowers. We really do always know from somewhere; perspectives really do differ profoundly; the dream of a view from nowhere really is elusive. Whether these truths force us all the way to Protagorean relativism, or can be honoured within a more objectivist framework, is exactly what the quarrel is about - and it is a quarrel we are still, all of us, conducting. To study Protagoras is to take up a question that will outlast us, as it has outlasted everyone who has engaged it for the last twenty-four centuries. The man whose books were burned and whose name became an insult turns out to have asked one of the questions that will never go away.
This is the opening of the lesson. The rest — the dialogue, the primary source, and the recall — is in the app.
You learned that Protagoras, long dismissed as a mere sophist by Plato’s influential polemic, was rehabilitated in modern times: the pragmatists (F. C. S. Schiller, William James) hailed ‘man is the measure’ as an anticipation of their view that truth is what works for human purposes; Nietzsche’s perspectivism (‘there…
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