…On Liberty also addresses freedom of thought and discussion in terms that remain instructive. His view is that progress depends on truth, that the truth is most likely to emerge from a constant collision of opinions, and that freedom of speech is necessary to generate such collisions. There are three essential components to his argument that free discussion is truth-generative. First, any opinion may be true, no matter how eccentric it seems at first, and so to suppress it is to slow the march of knowledge. Second, few opinions contain the whole truth, while many contain a “portion” of it—and only by bringing them into contact and conflict can any approximation of the whole truth be constructed. In an echo of Coleridge, he declares that usually “conflicting doctrines, instead being one true and the other false, share the truth between them.” Third, even if a received doctrine happens to be true, it becomes less vitally so unless subjected to open critique: “both teachers and learners go to sleep at their post, as soon as there is no enemy in the field.” (He certainly would have opposed the jailing of David Irving.)
Mill insists that religion should be subject to the same criticism as any other system of thought, regardless of the offence caused. I think we can be confident that Mill would be disappointed by the progress made on this issue in the last century and a half, and by the regress of the last half decade. He certainly anticipated those who wanted to turn only “intemperate” expressions of religious criticism into crimes. Mill gave no ground, pointing out that serious offence is taken “whenever the attack is telling and powerful.” There is no doubt where he would stand on the current debates on religious hatred, or on publication of the cartoons of Muhammad.
There are weaknesses in Mill’s free speech arguments, of course. It is not clear, as Bernard Williams pointed out in his last book, Truth and Truthfulness, that an absolutely free exchange of opinion is indeed the surest route to the production of truth, or its dissemination. But Mill’s case has considerable force in the contemporary debates about speech crimes. And it is all the stronger for its reliance on instrumental outcomes rather than on “human rights” grounds. I am not at all sure that I have a “right” to freedom of speech, but I am absolutely clear that it is to the detriment of us all if I am denied it…