As a guy who wrote no books, Davidson's two published collections have done the work of securing his legacy. In this volume, among other things, we have the papers that argue for two of his most important theses in philosophy of mind. (1) The behaviorists argued that every state of mind was at best a disposition to some behavior, as in Gilbert Ryle's _The Concept of Mind_. Davidson, in "Actions, Reasons, Causes" and a couple of other papers in this volume, laid bare one of the essential arguments that put down this view for good. We often have many reasons or other mental states upon which we do not act. But such beliefs or desires are still reasons, and still mental states--just ones that behaviorism can't account for. (2) Davidson argues for the oft-maligned but influential thesis of anomalous monism, as a strategy to resolve the worries arising from "materialism of the mental". If the mind is mere matter, then physics will eventually figure out its laws! Then where will our free will be? Davidson argues, relying on some tendentious claims about what a law is, that there can never be laws of the mental *even though* there are laws of the physical stuff. The mental is anomalous and not lawlike.
Anyway, this volume is a very important piece of recent philosophy of mind. It also sets into motion an important tradition of thinking about moral psychology, action theory and ethics from the perspective of reasons for agential action.