Explanatory Reduction, Conceptual Analysis, and Conceivability Arguments about the Mind Brie Gertler University of Wisconsin, Madison The current stand-off between reductionists and anti-reductionists about the mental has sparked a long-overdue reexamination of key issues in philosophi- cal methodology. 1 The resulting debate promises to advance our understand- ing of how empirical discoveries bear on the numerous philosophical problems which involve the analysis or reduction of kinds. The parties to this debate disagree about how, and to what extent, conceptual facts contribute to justify- ing explanatory reductions. My aim here is threefold: ~a! to show that conceptual facts play a more sig- nificant role in justifying explanatory reductions than most of the disputants recognize, 2 ~ b! to furnish an account of that role, and ~c! to trace the conse- quences of this account for conceivability arguments about the mind. I begin ~Section I ! by sketching an initial argument for the thesis that all justification for explanatory reductions is based in conceptual facts, in that our concept of a kind determines what qualifies as evidence for a reduction of the kind. The middle sections of the paper ~Sections II-V! defend this thesis from recent influ- ential objections. I extract from this defense a detailed model of how concepts contribute to explanatory reductions ~Section VI !. This model implies that reduc- tionists cannot simply dismiss, as irrelevant, conceivability arguments against reductionism about the mind. In the final section ~Section VII ! I rehearse a familiar brand of conceivability argument, and sketch the reductionist strat- egies for defusing this argument which remain available on the model of explan- atory reduction defended here. I then describe the anti-materialist rejoinders which that model makes available. I do not take a side in the debate over men- tal reductionism. My point is that the viability of reductionism must be decided on conceptual grounds and that, therefore, conceivability arguments are cru- cially important in evaluating materialism about the mind. NOÛS 36:1 ~2002! 22–49 © 2002 Blackwell Publishing Inc., 350 Main Street, Malden, MA 02148, USA, and 108 Cowley Road, Oxford OX4 1JF, UK. 22