  A central consideration adduced in support of internalist theses is the conceptual link between reasons and explanation. In an influential early discussion of reasons for action, Donald Davidson (1963) observed that a common form of explanation of why an agent acted as she did involves citing the reasons she had to act that way. He argued that because actions are always to be explained in terms of psychological states, we can identify reasons for actions with the desire-belief pairs that cause them. Since Davidson’s concern was with what explains actual action, rather than with what justifies prospective action, his discussion might seem to concern motivating reasons rather than normative reasons. But Davidson took his reasons to “rationalize” or justify as well as to explain action, and many philosophers subsequently concluded that the two kinds of reasons had to be closely, conceptually, connected.