ABSTRACT
Both experience and the seeming structure of the sciences suggest that some special scientific phenomena (broadly construed to include artifacts and the like) are synchronically dependent on lower-level physical phenomena, and yet are also distinct from and distinctively efficacious as compared to the lower-level physical phenomena upon which they depend. This characteristic combination of dependence and autonomy serves to motivate the notion of metaphysical emergence as important to understanding natural reality. Indeed, and reflecting different specific interpretations of the dependence or autonomy at issue, there is at present a great diversity of contemporary accounts of metaphysical emergence. As I’ll here argue, however, many of these accounts – thankfully, not all – fail to satisfy one or both of the following criteria of adequacy:
The criterion of appropriate contrast: Reflecting that metaphysically emergent phenomena are supposed to be distinct from the lower-level phenomena upon which they synchronically depend, an adequate account of metaphysical emergence must provide a clear (i.e., explicit) basis for ruling out that phenomena it deems emergent can be given an ontologically reductionist treatment – that is, it must provide a clear basis for ruling out that emergent phenomena are identical to dependence base phenomena. Relatedly, an adequate account of metaphysical emergence must provide a clear basis for establishing that the phenomena it deems emergent are not just epistemically or representationally emergent. For example, even supposing that seemingly metaphysically emergent phenomena are always surprising to those who first encounter them, then (since being surprising is in itself compatible with being identical to some lower-level phenomenon) an account of metaphysical emergence in terms of such a response would fail to satisfy the criterion of appropriate contrast.
The criterion of illuminating contrast: An adequate account of metaphysical emergence must not only provide a clear basis for contrasting such emergence with ontological reduction, but moreover do so in a way that provides an illuminating – that is, explanatorily relevant – basis for understanding how such failures of reduction might occur. Relatedly, an adequate account of metaphysical emergence must provide a clear basis for the in-principle resolution of disputes over whether some phenomenon is metaphysically emergent, in a way going beyond appeal to brute intuitions or irrelevant distinctions. For example, even supposing that an oracle exists who can infallibly report whether a given phenomenon is metaphysically emergent, an account pitched in terms of such oracular pronouncements would fail to 158illuminate what it is to be metaphysically emergent and so would fail to satisfy the criterion of illuminating contrast. More plausibly, an account according to which metaphysically emergent phenomena are dependent on but ontologically irreducible to lower-level physical phenomena, but which did not provide any explanatory insight into how, exactly, some dependent goings-on might be so irreducible, would lead directly to stalemate between emergentists and reductionists (e.g., with regard to the status as emergent of certain mental states), and so would fail to satisfy the criterion of illuminating contrast.
There are, of course, other important criteria of adequacy on an account of metaphysical emergence. Foremost among these is to provide a basis for accommodating the distinctive efficacy of metaphysically emergent phenomena – and moreover, to do so in a way that is able to address concerns, notably raised by Kim (in, e.g., his 1989 and 1993), according to which certain varieties of metaphysical emergence give rise to problematic causal overdetermination. Treatment of this and other criteria of adequacy is beyond the scope of this chapter, though I believe such treatment would support the methodological morals I will later draw. 1