Two notions of intentional action? Solving a puzzle in Anscombe’s Intention

The account of intentional action Anscombe provides in her (1957) Intention has had a huge influence on the development of contemporary action theory. But what is intentional action, according to Anscombe? She seems to give two different answers, saying first that they are actions to which a special sense of the question ‘Why?’ is applicable, and second that they form a sub-class of the things a person knows without observation. Anscombe gives no explicit account of how these two characterizations converge on a single phenomenon, leaving us with a puzzle. I solve the puzzle by elucidating Anscombe's two characterizations in concert with several other key concepts in ‘Intention’, including, ‘practical reasons’, the sui generis kind of explanation these provide, the distinction between ‘practical’ and ‘speculative’ knowledge, the formal features which mark this distinction, and Anscombe's characterization of practical knowledge as knowledge ‘in intention’