How does rational explanation—the explanation of actions and attitudes in terms of an agent’s reasons—relate to other kinds of explanation? Is it just like other kinds of explanation? Is it fundamentally unlike other kinds of explanation? One way to make progress on these questions is by getting clear on the semantics of ‘why’-questions and their canonical answers. That’s what I aim to do in this talk. Drawing on recent work in the syntax and semantics of interrogatives, I argue that ‘why’-questions are, in most important respects, syntactically and semantically just like other ‘wh’-questions. In particular, like other ‘wh’-questions, ‘why’-questions, at some level, involve a quantificational expression associated with a domain which can be contextually restricted. Given this, we should expect the kind of semantic context-sensitivity we find with other ‘wh’-questions to show up in ‘why’-questions. And we do. Or so I argue. Having done so, I extend the argument to the case of ‘because’. I argue that in order to be suited to its role as a constituent of sentences which express semantic answers to ‘why’-questions in contexts, ‘because’ must be contextually sensitive to the same features of a context of utterance that a ‘why’-question is. I then briefly speculate on how this understanding of the semantics of ‘because’ and ‘why’ might bear on the questions above.