Three roles of ideal theory

Rawlsian ideal theory is meant to perform various roles in non-ideal theory. In this paper, I distinguish between three roles, and I consider the extent to which we can expect ideal theory to perform them. It is meant to serve as a target to guide non-ideal theorising in the long-term. It is also supposed to provide a way of comparing different injustices to tell us which is worst and therefore in most urgent need of a remedy. Finally, ideal theory is the basis for a model of fairness that restricts the set of morally permissible measures in non-ideal theory. I show how the first two roles—the target and urgency roles—are less plausible than the fairness role.