Abstract
Underlying many of our uneasy debates about the social and moral responsibilities of professionals is a form of scepticism about the role of reason in morals. This claim is illustrated by examples drawn from both the pure-knowledge and applied-knowledge professionals. Hume's sceptical views about the role of reason in our knowledge of matters of fact and in morals are critically examined. An alternative theory of reasonableness that combines elements of foundationalism and coherentism, cognitivism and emotivism, and that emphasizes a process of congruence achieved through reflection, dialectic and dialogue is sketched and illustrated. It is claimed that this notion of reasonableness is the one actually involved in science, law and morals