Can presidential systems be just? Suppose you were in a position of constitutional choice akin to John Rawls's original position; you have full mastery of social-scientific knowledge, but know nothing about your society or the place you occupy in it, save that it is an industrial society. Would it then be permissible to choose a presidential system of government over a semi-presidential system or a parliamentary system? Answering this question is a precondition for understanding which political institutions are the most desirable, and which best satisfy the requirements of justice. This paper argues that were you in such a position, you morally ought not to choose presidentialism over its semi-presidential or parliamentary rivals. I call this the Anti-Presidentialism Thesis. My argument for the Thesis is that the workings of presidential systems guarantee that some government officer - the President - will be unaccountable to other officers for her public acts, and we ought not to choose such a system, because such unaccountability threatens each citizen's capacity for self-government. In arguing for the Thesis, I analyze the nature of presidential, semi-presidential, and parliamentary systems. I then mount the argument from unaccountability to other officers. I then consider and refute the seven most popular arguments for presidential systems: the arguments from direct election, from direct accountability to the voters, from identifying alternative governments, from arbitrating conflict, from separation of powers, from executive stability, and from dispatch.