Metaphysical Emergence

Book excerpt: Both the special sciences and ordinary experience present us with a world of macro-entities - trees, birds, lakes, mountains, humans, houses, and sculptures, to name a few - which materially depend on lower-level configurations, but which are also distinct from and distinctively efficacious ascompared to those configurations. This give rise to two key questions. First, what is metaphysical emergence, more precisely? Second, is there actually any metaphysical emergence? Metaphysical Emergence provides clear, compelling, and systematic answers to these questions. Wilson argues that thereare two and only two forms of metaphysical emergence that make sense of the target cases: 'Weak' emergence, whereby a macro-entity or feature has a proper subset of the powers of its base-level configuration, and 'Strong' emergence, whereby a macro-entity or feature has a new power as compared toits base-level configuration. Given that the lower-level configurations are physical, Weak emergence unifies and accommodates diverse accounts of realization associated with varieties of non-reductive physicalism, whereas Strong emergence unifies and accommodates anti-physicalist views according towhich there may be fundamentally novel features, forces, interactions, or laws at higher levels of compositional complexity. After defending each form of emergence from various objections, Wilson considers whether complex systems, ordinary objects, consciousness, and free will are actually eitherWeakly or Strongly metaphysically emergent. She argues that Weak emergence is quite common, and that Strong emergence, while in most cases at best a live empirical possibility, is instantiated for the important case of free will.