This is the introduction to a volume of new essays in the metaphysics of moral responsibility by John Martin Fischer, Carl Ginet, Ishtiyaque Haji, Alfred R. Mele, Derk Pereboom, Paul Russell, and Peter van Inwagen. I provide some background for the essays, cover the main debates in the metaphysics of moral responsibility, and emphasize some of the authors' contributions to this area of philosophy.

In the tradition of substructural logics, it has been claimed for a long time that conjunction and inclusive disjunction are ambiguous:we should, in fact, distinguish between ‘lattice’ connectives (also called additive or extensional) and ‘group’ connectives (also called multiplicative or intensional). We argue that an analogous ambiguity affects the quantifiers. Moreover, we show how such a perspective could yield solutions for two well-known logical puzzles: McGee’s counterexample to modus ponens and the lottery paradox.