Ever since its first publication in 1970, Amartya Sen's paper “The Impossibility of a Paretian Liberal” (reprinted in Sen, 1982) has served as the starting point for almost all discussions of liberty in social choice theory. However, a number of people, myself included, have argued that Sen's theorem rests on a misleading characterization of liberty (Nozick, 1974, pp. 164–166; Bernholz, 1974; Sugden, 1978, 1981, pp. 193–198; Garden-fors, 1981; Levi, 1982). In a recent paper, addressed to a philosophical audience, Sen (1983) has provided a careful defence of his theorem against this charge. I shall argue that this defence does not work.