Abstract

It is now standard to distinguish between two kinds of rationality: substantive rationality, which consists in holding attitudes that are substantively reasonable or justified, and structural rationality, which consists in holding attitudes that fit together in the right ways. What, if anything, unifies these two kinds of rationality? In this paper, I propose that norms of rationality arise because we are epistemically limited beings who cannot directly ensure the correctness of our attitudes. Substantive and structural rationality represent two different ways of manifesting a fundamental commitment to getting things correct, given our epistemic limitations. Correspondingly, substantive and structural irrationality are distinct rational failures. Substantively irrational attitudes involve a failure to live up to the commitments that constitute those attitudes. Structurally irrational combinations of attitudes are constituted by inconsistent commitments, which guarantees that we will fail to live up to at least some of our commitments in holding these attitudes.