This dissertation is a defense of the claim that ideal theory is democratic theory. I begin with an interpretation of Plato's famous critique of democracy. One is properly equipped, Plato argues, to exercise authority in politics in virtue of the possession of knowledge. Therefore, sane political arrangements involve distributing political authority to experts. But democracy does just the opposite: by putting political authority in the hands of the majority, it substitutes ignorance for knowledge where we can least afford it. I turn to Aristotle for help in answering this challenge. Aristotle argues that the political art belongs to an important category of rational but non-technical capacities, the exercise of which is essential to leading a good life. The Platonic argument in favor of rule by experts is objectionable because one is equipped to participate in the government of the affairs of one's community as a result of ones upbringing and life experience as a member of that community, and because it is wrong to deprive someone of the opportunity to exercise the capacity for self-government, even if this capacity is flawed. In the second half of my dissertation I explore the consequences of this argument for ideal theory. I argue against “value pluralism”: the doctrine that political values, like freedom, equality, and justice, conflict with one another. In order to be practicable, a conception of the ideal must consist of values that are compatible rather than incompatible. I also argue against “the thesis of moderate scarcity”: the claim that for ideal theory to be practicable we must assume that the polity lacks, to a moderate degree, the material resources it needs. On the contrary, for the political ideal to be practicable it must require only limited material resources. For the purposes of ideal theory we must assume that material resources are sufficient rather than moderately scarce. The conclusion of my argument is that ideal theory is the theory of a democratically self-organized society, governing itself in accordance with a set of compatible values, in conditions of sufficient material resources.