The classical analysis of relevance in probabilistic terms does not fit legal, moral or conversational relevance, and, though analysis in terms of a psychological model may fit conversational relevance, it certainly does not fit legal, moral or evidential relevance. It is important to notice here that some sentences are ambiguous between conversational and non-conversational relevance. But, if and only ifR is relevant to a questionQ, R is a reason, though not necessarily a complete or conclusive reason, for accepting or rejecting something as an answer toQ. Reasons of this kind are governed by appropriate covering laws or principled probabilities and a number of questions thus arise about the relationship between relevance and certain formal-logical properties.