Metaphysical Emergence as Higher-Level Naturalness

This chapter offers a new conception of the metaphysics underlying emergent phenomena. The account works by distinguishing between fundamentality and naturalness (in the sense employed by David Lewis) and by acknowledging perfectly natural properties at non-fundamental levels of reality. Its starting point is Elizabeth Barnes’s proposal to characterize the emergent as fundamental but dependent, criticizing it on the ground that it undermines the theoretical work we need fundamentality to do. Nonetheless, Barnes is on the right track: emergence is linked to a selective metaphysical privileging of higher-level subject-matters. Building on this idea, the chapter proposes an alternative account of the emergent as non-fundamental but (at least relatively) natural. It then develops a framework for thinking about naturalness at non-fundamental levels which makes essential use of the notion of a subject-matter. Drawing on recent work by Jeffrey Russell, it is shown how the naturalness of a subject matter can be modelled in well-understood ways using the machinery of partitions on sets of worlds. The chapter concludes by exploring some initial consequences of the proposed account for debates over emergentism and reductionism. Its overall aim is to make conceptual room for a certain general form of metaphysical emergence which is compatible with supervenience of the emergent. In a slogan: metaphysical emergence is eliteness of higher-level properties.