Abstract

Entire moral philosophies have been rejected for ruling out the possibility of failure. This “fallibility constraint” (also sometimes called the “error constraint”) cannot be justified by appealing either to Wittgensteinian considerations about rules or to the moral importance of alternate possibilities. I propose instead that support for such a constraint in ethics can be found in the Strawsonian reactive attitudes. I then use the constraint to reveal hidden weaknesses in contemporary contstitutivist strategies to ground moral normativity such as Christine Korsgaard’s, and also to reveal hidden strengths in historical accounts of morality such as Bishop Butler’s. We will have reason to reject any moral theory that makes constitutivism’s mistake, but only because we have reason not to reject the fallibility constraint itself. The way this ethical fallibility can be justified suggests a general principle that could be used to justify fallibility constraints in other normative domains such as practical reason, epistemology, the philosophy of language, and the philosophy of mind.