Introduction

A remarkable aspect of John Stuart Mill's argument in On Liberty (1859) is his claim to be defending “one very simple principle”: that “the only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others. His own good, either physical or moral, is not a sufficient warrant” (OL i.9; Mill 1977: 223, emphasis added). Prevention of harm to others is a necessary condition for the legitimate exercise of any form of coercion against “human beings in the maturity of their faculties”. The implication usually seized upon by commentators, which, however, is not the only possible one, is that any adult ought to be free to do anything that does not harm other people. In other words, a civil society has no legitimate authority to regulate any conduct that does not pose a definite risk of harm to others, and should not even consider regulating it. Mill seems to confirm this interpretive strategy later in the same paragraph: “The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign” (ibid., emphasis added).