The idea of the “marketplace of ideas” in which truth wins out through competition with error has a strong tradition in the U.S. Suggested in nascent form by Milton and Mill, US Supreme Court decisions appeal to it in free speech decisions, and it frequently appears in commentary and everyday conversations. It continues to hold axiomatic status in the U.S., at least outside of a set of college campuses.
Justice Holmes in his famous Abrams’ dissent styles the claim that
when men have realized that time has upset many fighting faiths, they may come to believe even more than they believe the very foundations of their own conduct that the ultimate good desired is better reached by free trade in ideas — that the best test of truth is the power of the thought to get itself accepted in the competition of the market . . .
So, too, in On Liberty, J.S. Mill argues that “silencing the expression of an opinion” robs humanity:
If the opinion is right, they are deprived of the opportunity of exchanging error for truth: if wrong, they lose, what is almost as great a benefit, the clearer perception and livelier impression of truth, produced by its collision with error.
Both appeal to a social process in which truth wins out in a competitive process with falsehood.
While preceding Mill by a century, and Holmes by more than a century hand a half, in his (quite curious) First Discourse, Jean-Jacques Rousseau advances much the opposite claim to Mill, Holmes, and others. While he focuses his discussion on “arts and sciences,” his argument would seem to engage the implicit social process of the Millian postulate more generally:
How many errors, a thousand times more dangerous than the truth is useful, must be surmounted in order to reach the truth? The disadvantage is evident, for falsity is susceptible of infinite combinations, whereas truth has only one form. Besides, who seeks it sincerely? Even with the best intentions, by what signs is one certain to recognize it? In this multitude of different opinions, what will be our one criterium in order to judge it properly?
Rousseau suggests several lines of thought at odds with the Millian claim. First, he hints the sheer volume of mistaken ideas can drown out good ideas. In a flood of babble, how can one discern the good among the bad? Rousseau’s view suggests a counter analogy of sorts in the form of an epistemological Gresham’s law: As bad money drives out good money in the actual marketplace, perhaps bad ideas drive out good ideas in the market place of ideas. Or perhaps we could express it in a weaker form, that bad ideas simply drown out good ideas.
Secondly, Rousseau hints at a more pessimistic anthropology than Mill & etc. “Who seek [the truth] sincerely,” he asks? The Millian postulate assumes that people naturally, even if slowly and gradually, accept the true, that we seek the truth sincerely. Rousseau pushes on the anthropology implicit in the Millian view. He advances a darker anthropology throughout his First Discourse. I don’t know that it would be accurate to term it an Augustinian anthropology. But if we were skeptical whether humans indeed were naturally attracted to truth – instead being those who “suppress the truth in unrighteousness,” as Paul put it in his epistle to the Romans – perhaps a marketplace of ideas would lead to a Gresham-like outcome in which truth gets buried by falsehood rather than one in which truth wins out.
Finally, then, Rousseau asks whether and how people recognize the truth even if we seek for it sincerely. How do we judge whether we arrive at the truth if in fact we do not already know the truth? But if we already know the truth, then on the terms of the Millian perspective itself it need not be uncovered through the competitive process of the marketplace of ideas. If we in fact don’t know the truth, then how do we know it is increasingly approximated by the process the view advances?
Rousseau’s claims inverts Millian claims at critical points. Rousseau’s pessimistic views of humanity and the sociology of knowledge clash distinctly with the optimism of the Millian view.
Yet even if we were to accept Rousseau’s view, and reject the Millian view that competition in the marketplace of ideas leads to the success of truth, it wouldn’t seem to provide any greater warrant for censorship than the Millian view itself. After all, human magistrates have no greater claim to perceiving the truth than anyone else in Rousseau’s argument. So what justification would there be to allow a magistrate to privilege one opinion over another; to allow one falsehood to impose on all the other falsehoods? A pessimistic portrait to be sure – I guess it would be “let a thousand weeds fester” rather than “let a thousand flowers bloom” – but one that does not justify censorship despite rejecting the assumptions of the Millian view.
In any event, Rousseau’s argument provides us with a contrarian counterpoint to the concept of the marketplace of ideas, and so provides a useful opportunity to muse a little more deeply on why we think truth naturally wins out in competition with error.
 Abrams v. United States, 250 U.S. 616, 630 (1919)
 The Basic Writings of John Stuart Mill (Modern Library Classics, 2002): On Liberty, 19.
 The Major Political Writings of Jean-Jacques Rousseau (University of Chicago Press, 2012): Discourse on the Sciences and the Arts, 24.