Charles Sanders Peirce offers a number of arguments against the rational application of theory to morality, suggesting instead that morality should be grounded in instinct. Peirce maintains that we currently lack the scientific knowledge that would justify a rational structuring of morality. This being the case, philosophically generated moralities cannot be otherwise than dogmatic and dangerous. In this paper, I contend that Peirce’s critique of what I call “dogmatic-philosophical morality” should be taken very seriously, but I also claim that the (...) purely instinctive morality Peirce endorses is liable to a danger of its own, namely fanaticism. Indeed, Peirce himself recognizes this danger. As an alternative, I sketch a form of “pragmatic morality” that attempts to sidestep the dogmatism of philosophical morality and the fanaticism of instinctive morality. This form of morality avoids philosophical dogmatism by treating extant instincts as the postulates and materials with which it works. It avoids instinctive fanaticism by allowing a role to reason. By exhibiting fallibilism, revisability, pluralism, and meliorism, this type of reasoning can avoid the dogmatism of the philosophical kind of morality Peirce critiques. (shrink)