Emergence and Reduction

Abstract Ontological reductionism and strong emergentism (henceforth ‘reductionism’ and ‘emergentism’) are two broad conceptions of how the discoveries of different sciences might fit together. Reductionism and emergentism disagree about the causal completeness of the processes studied by physics, or equivalently, the closure of such processes with respect to interventions from processes studied by so-called special sciences. This chapter raises epistemological questions about this metaphysical debate: what kinds of scientific evidence are available to address it? Critics of emergentism have charged that it seems attractive only because it is not articulated with enough precision: it is either (i) incoherent, or (ii) anodyne because it fails to exclude a broadly reductionist view of the causal structure of the world, or (iii) inconsistent with key scientific discoveries that support completeness. It is out of place in twenty-first-century philosophy to think that the impossibility of emergentism can be established a priori, so the question posed by this chapter is, how strongly do empirical discoveries really challenge emergentism? It critically examines influential arguments presented by Brian McLaughlin and David Papineau (among others), arguing that it is unclear which specific scientific achievements they cite in favour of reductionism, and that they fatally misinterpret emergentism. Using the relationship between determinism and Newtonian mechanics as a historical parallel, it is also argued that scientists and philosophers sometimes draw far-reaching metaphysical conclusions on slim scientific bases, conclusions which are rejected by later generations. Arguments for the completeness of physics are also the products of hubris and should be abandoned.