Abstract

Levels-of-reality talk is common among practicing scientists and philosophers of science, yet such talk of levels has been criticized by Jaegwon Kim, Amie Thomasson, and Angela Potochnik, which I analyze into three objections of increasing strength. The first requires abandoning only some of the wilder claims about levels, while the second prunes off many biological uses, and the third poses serious challenges even for metaphysicians. Metaphysicians who wish to save realism about levels must be prepared to make serious revisions. I argue for a novel approach which carves up levels using a neo-Aristotelian answer to the question of fundamental mereology which takes substances as the tiles of the world and uses metaphysical priority aconformities these generate in the mereological graph to identify levels. This emergentist account of levels is more coherent than varieties less connected to mereological structure, and places fewer constraints on that mereological structure than views like van Inwagen’s. While starkly revisionist, it fares better in recovering historical levels discourse than competitors like material atomism and priority monism. Further, the most painful revision is treating much of the biological levels discourse as representation and metaphor, but Potochnik argues that such talk was never a good candidate for metaphysics.