This essay discusses and criticizes the claim that normative political theory canbe (justifiably and fruitfully) divided into two parts—a part havingto do with ideal theory which assumes full compliance and abstracts away fromissues having to do with implementation and, contrasting with this, a nonidealpart having to do with implementation and with rules and institutionsappropriate for conditions of partial compliance. On this conception of idealtheory, empirical facts about human behavior and motivation, connected to issuessurrounding compliance and implementation, are irrelevant to ideal theory,although such facts can be relevant to the nonideal part of normative theory. Iargue against this conception, holding instead that such empirical facts arerelevant to most or all of normative political theory, including“fundamental” normative principles.
