In this paper I want to explore certain parallels between the logic of action and the logic of belief or, as it might otherwise be put, between practical and theoretical reasoning and rationality. The parallels will be seen to involve an ontological dimension as well as psychological and linguistic dimensions. It may help to begin by mentioning how I was drawn into an examination of these parallels. This was through becoming convinced of the correctness of an externalist account of reasons for action, having been persuaded of this by, amongst other things, arguments found in Jonathan Dancy’s recent book on the subject, Practical Reality.1 Externalism about reasons for action appeared to me to be, on reflection, the only view that one could plausibly adopt in conjunction with a libertarian account of free will—the latter being a position which I am now convinced is not only coherent but entirely defensible and indeed correct. Oddly enough, however, recent debates concerning internalist versus externalist accounts of reasons for action tend to have been dominated by moral philosophers, whereas those concerning compatibilist versus libertarian accounts of free will tend to have been dominated by philosophers of action. As a consequence of this, the two debates have been carried on relatively independently of each other—in my view, to the detriment of both. The present paper is part of a larger exercise of trying to bring them together.