Abstract

John Stuart Mill’s defense of free discussion in On Liberty includes the claim that silencing discussion implies an “assumption of infallibility.” This claim is often dismissed as absurd on the ground that a censor might attempt to silence an opinion he believes to be true but pernicious, or because rational assurance short of infallibility is obviously sufficient to justify censorship. This paper argues that Mill is concerned about the epistemic position one assumes with regard to future persons and circumstances as a result of attempting to settle some matter irremediably. The irrationality of this "assumption" sets an important authority-limiting constraint on both social authority and individuals in matters that otherwise would fall under their rightful control. For individuals, in particular, it explains Mill's restriction on selling oneself into irrevocable slavery.