The book develops, defends, and applies a "Dual Scale" model of weighing reasons to resolve various issues in ethics. It tells you everything you ever wanted to know about weighing reasons and probably a lot of stuff you didn't want to know too. It addresses, among other things, what the general issue of weighing reasons is; what it is to weigh reasons correctly; whether reasons have more than one weight value (e.g., justifying, requiring, and/or commending weight); whether weight values are (...) context sensitive; how to tell what the weights of reasons are; how reasons for are related to reasons against; and how the weights of reasons aggregate. After addressing such issues, it explains a number of puzzling phenomena in ethics, such as the All or Nothing Problem, the normative significance of small improvements, and the intransitivity of the makes-it-permissible-to-act-against relation. (shrink)

Some philosophers think that knowledge or justification is both necessary and sufficient for rational action: they endorse knowledge-action or justification-action biconditionals. This paper offers a novel, metaphysical challenge to these biconditionals, which proceeds with a familiar question: What depends on what? If you know that p iff it is rational for you to act on p, do you know that p partly because it is rational for you to act on p, or is it rational for you to act on (...) p partly because you know that p? And a structurally similar question can be asked regarding justification-action biconditionals. I argue that proponents of these biconditionals cannot give a satisfactory answer to these questions. This is because each direction of these biconditionals strongly supports an opposite order of explanation to the one that is supported by the other direction. Given the traditional assumption that metaphysical explanations—even partial ones—are asymmetric, I argue that these biconditionals should be rejected. While knowledge might be necessary for rational action, and it might be sufficient, it cannot be both. And the same goes for justification. (shrink)

According to a standard picture, normative reasons do not extend beyond the boundaries of agency. If something isn’t an agent, then there can’t be normative reasons for it to do one thing rather than another. This paper argues that the standard picture is false. There are reasons for smoke detectors to alarm when exposed to smoke, and for Venus Flytraps to close around their prey when stimulated. I argue that the collapse of the standard picture has important implications for philosophical (...) debates about reasons, and especially serious consequences for theories that analyse normative reasons in terms of the standards of good practical reasoning. (shrink)