Of the terrible doubt of appearances an essay in moral epistemology

Recreational killing strikes most of us as wrong. Such "moral appearances," in which the world appears to us to be a certain way, morally speaking, play an important role in moral epistemology, usually in the guise of "moral intuitions.";Moral appearances are natural phenomena, however, and scientists are discovering the psychological mechanisms underlying them. Recent research suggests a "developmental sentimentalist" model of moral appearances, on which moral appearances arise from "moral sentiments," which develop through a process of emotional conditioning.;This naturalistic account of moral appearances allows us to explain our moral appearances without supposing that their intentional content is true. This explanatory irrelevance gives us a prima facie reason to discount moral appearances when deciding which moral claims to endorse. Sensibility theory and rational intuitionism attempt to validate the use of moral appearances in the face of their explanatory irrelevance. I argue that neither theory succeeds.;But it seems that moral appearances cannot be discounted altogether, for it is unclear how we could justify moral claims without them. I introduce the notion of "practical coherence" as a basis for deciding between alternative systems of evaluative claims, including both moral and nonmoral claims. I assume that evaluative claims have, as at least one function, the prescription of actions. A system of evaluative claims is practically coherent to the extent that, given current circumstances, performing the actions prescribed by any one evaluative claim in the system increases, or at least does not reduce, the probability of being able to perform the actions prescribed by other claims in the system. Because the practical relations between different actions are determined by the world, not by what we think, practical coherence ties evaluative systems to the world. This dependence on both the values that we hold and the attitude-independent relations among various actions yields an unusual combination of limited ethical relativism and moderate moral realism. But more importantly, practical coherence leads to a multidisciplinary method of ethical inquiry that will allow us to devise more satisfying answers to the central question of ethics: How should one live?...