The viability of Weak emergence

Wilson considers and responds to a range of objections to the schema for Weak emergence and the associated ‘subset of powers’-based approach to realization. These include that satisfaction of the conditions in the schema is compatible with anti-realism about, reductionism about, or physical unacceptability of the emergent entities or features, or is not necessary for physically acceptable emergence. Each challenge admits of one or more responses available on any sensible implementation of the schema for Weak emergence; certain additional responses draw on features of Wilson’s preferred accounts of Weak emergence, appealing to the determinable/determinate relation or to an elimination of degrees of freedom.

Complex systems

Wilson considers whether complex systems are either Weakly or Strongly emergent. She first traces the demise of nonlinearity as criterial of Strong emergence, and offers a new criterion in terms of apparent violations of a conservation law. By these lights, the Strong emergence of complex systems remains a live but currently unmotivated possibility. Wilson then argues that while appeals to algorithmic incompressibility, dynamic self-organization, and universality do not establish the Weak emergence of complex systems, cases can be made that these or related features satisfy the conditions in the schema. Most promisingly, complex systems exhibiting universality have eliminated degrees of freedom (DOF), and so are Weakly emergent by lights of a DOF-based account; and other complex systems (gliders in the Game of Life; flocks of birds) may also be seen as Weakly emergent by these lights.

Consciousness

Wilson considers whether consciousness is either Weakly or Strongly emergent. Some have seen consciousness as the best case for a Strongly emergent phenomenon, reflecting that subjective or qualitative aspects of consciousness depart so greatly from physical features that some anti-physicalist view (perhaps Strong emergence) must be true. Wilson considers two such ‘explanatory gap’ strategies, associated with the knowledge argument (Jackson 1982, 1986) and the conceivability argument (Chalmers 1996, 2009). She argues that each strategy fails, for reasons not much previously explored; hence while the Strong emergence of consciousness remains an open empirical possibility, there is currently no motivation for taking this to actually be so. Wilson then argues that attention to the determinable nature of qualitative conscious states provides good reason to take such states to be Weakly emergent by lights of a determinable-based account, and defends the application of such an account to mental states against various objections.

Ordinary objects

Wilson considers whether ordinary (inanimate) objects are either Weakly or Strongly emergent. First, she argues that ordinary objects are at least Weakly emergent: first, by lights of a degrees of freedom (DOF)-based account, reflecting that quantum DOF are eliminated from those of ordinary objects in the classical limit; second, by lights of a functional realization account, reflecting a conception of artifacts as associated with sortal properties and distinctive functional roles; third, by lights of a determinable-based account, reflecting that ordinary objects have metaphysically indeterminate boundaries, which are best treated by appeal to a determinable-based account of metaphysical indeterminacy. While the Strong emergence of ordinary objects remains an open empirical possibility, the best such case involves artifacts: artifacts might be Strongly emergent, if the states of consciousness that determine what powers are possessed by artifacts are Strongly emergent, as is explored in Chapter 7.

Free will

Wilson considers whether free will is either Weakly or Strongly emergent. She starts by drawing on Bernstein and Wilson (2016) to present a framework for connecting positions on the problem of free will with positions on the problem of mental (higher-level) causation. Bernstein and Wilson argue that compatibilist accounts implement a ‘proper subset’ strategy relevantly similar to that implemented by nonreductive physicalists/Weak emergentists; here Wilson extends this result to establish that the compatibilist strategy entails satisfaction of the conditions in Weak emergence. Wilson then argues that libertarian accounts implement a ‘new power’ strategy entailing satisfaction of the conditions on Strong emergence. Wilson goes on to suggest that free will of the compatibilist/Weakly emergent variety is plausibly widespread, and to present a novel argument for taking some instances of seemingly free choice to be Strongly emergent.

Key issues and questions

Both the special sciences and ordinary experience suggest that there is metaphysical emergence, whereby there are macro-entities which materially depend on lower-level configurations, but which are also distinct from and distinctively efficacious as compared to these configurations. Such appearances give rise to two key questions. First, what is metaphysical emergence, more precisely? Second, is there actually any metaphysical emergence? Wilson registers the aim of providing clear, compelling, systematic answers to these questions; she discusses the overall strategy and associated plan for the book; and she surveys certain operative notions, including those of the physical, levels, the fundamental, causes and powers, and methodology.

Metaphysical emergence: next steps

Wilson summarizes the results of the book and calls attention to some phenomena whose status as metaphysically emergent deserves further attention, including quantum entanglement, molecular structure, biological systems, and brain dynamics. She closes with some methodological observations pointing towards other ways in which attention to broadly mereological relationships between sets of powers might serve to shed light on other aspects of higher-level reality, beyond metaphysical emergence.

The viability of Strong emergence

Wilson considers and responds to a range of objections to the schema for Strong emergence and the associated ‘new power’ approach to physically unacceptable emergence. These objections include that satisfaction of the conditions in the schema renders Strong emergence naturalistically unacceptable or ‘scientifically irrelevant’, is compatible with physicalism, is impossible owing to the base entity or feature inheriting any purportedly novel power, or is not necessary for physically unacceptable emergence. Each challenge admits of one or more responses available on any sensible implementation of the schema for Strong emergence; certain additional responses draw on features of Wilson’s preferred ‘fundamental interaction-relative’ account of Strong emergence.

Two schemas for metaphysical emergence

Wilson presents the problem of higher-level causation (Kim 1989, 1993, 1998), according to which metaphysical emergence gives rise to problematic causal overdetermination. She argues that there are two and only two strategies of response to this problem of making sense of metaphysical emergence. One strategy provides a schematic basis for ‘Weak’ (physically acceptable) emergence; core and crucial here is that a macro-entity or feature has a proper subset of the powers of its base-level configuration. The other strategy provides a schematic basis for ‘Strong’ (physically unacceptable) emergence; core and crucial here is that a macro-entity or feature has a new power as compared to its base-level configuration. Wilson shows that a range of seemingly diverse accounts of metaphysical emergence are plausibly seen as satisfying the conditions in one or the other schema, and thus are more unified than they appear.