This thesis investigates the relationship between the concepts of justice and responsibility. It is important to decide what the relationship is, because the details of a theory of justice will depend on it. Four possible views of the relationship are outlined, and arguments are canvassed for and against one of them, which I call naturalism. Naturalism is appealing because it offers to make theories of justice independent of troubling agency-implicating judgements. But I argue that naturalism is false, because political argument, including theories of justice, cannot do without such judgements. They play an essential role in determining which range of possible actions or arrangements is relevant to a political argument. The argument against naturalism is in two parts. The first part analyses the concept of benefit, underlining the feature of that concept which makes agency-implicating judgements necessary for those who employ it. This first anti-naturalist argument is directed to arguments in ideal theory, in Rawls's sense of that term. The second part of the argument against naturalism is directed to deliberative arguments. Naturalism is, I claim, a much more plausible doctrine if it is understood to apply to such arguments in particular. But I argue that it is nevertheless false, because it leaves us unable to account for some of the reasons persons have for resisting acquiescence. Discussion of the rationality of acquiescence leads into discussion of the nature of deliberation. I argue that a feature of some consequentialist models of deliberation, which I call the hard-nosed view, must be rejected. I end with a comparison of the resulting view with Kant's ethics, and some variant forms of consequentialism.