Thick Concepts and the Moral Brain

Abstract Drawing on Williams’ distinction between thin and thick ethical concepts, I argue that current moral neuroscience and psychology unwarrantedly restrict their researches to thin morality only. Experiments typically investigate subjects’ judgments about rightness, appropriateness, or permissibility, that is, thin concepts. The nature and workings of thick concepts – e.g. , dignity, integrity, humanness, cruelty, pettiness, exploitation, or fanaticism – have not been empirically investigated; hence, they are absent from recent theories about morality. This may seem like a minor oversight, which some additional research can redress. I argue that the fix is not that simple: thick concepts challenge one of the theoretical backbones of much moral psychology and neuroscience; they challenge the conception of a hardwired and universal moral capacity in a way that thin concepts do not. In the conclusion I argue that the burgeoning science of morality should include both thin and thick, and that it should include the contributions of psychologists and neuroscientists as well as those of anthropologists, historians, and sociologists.