I present an interpretation of ideal theory that is grounded in the idea of society as a fair scheme of cooperation, which Rawls describes as the most fundamental idea of justice as fairness. A key element of the Rawlsian idea of cooperation, I claim, is that the individual participants of a genuinely cooperative scheme—whatever its scale—are morally accountable to each other for complying with the scheme’s rules. This means that each participant has the moral standing to demand of the others (...) that they comply with the rules. I argue that the logic of these moral demands requires that the scheme’s rules be worked out on the basis of a strict compliance assumption. In justice as fairness, society as a whole is a grand scheme of cooperation. The principles of justice constitute the moral terms of association for this cooperative scheme, and hence define the moral demands that citizens, as such, may make of one another. Thus, these principles of justice must likewise be worked out on the basis of a strict compliance assumption. I contrast this interpretation with the standard telic alternative, which grounds the strict compliance assumption in its role as part of the theory of a realistic utopia, and argue for the possibility of non-utopian ideal theories. (shrink)