 Affirming that there are emergent phenomena that are both dependent on and yet autonomous with respect to underlying physical structures leaves a great deal open, however, as both of the characteristics have been explicated in diverse ways (see Van Gulick 2001, Gillett 2002, Wilson 2015, and Humphreys 2016 for discussions highlighting this diversity). Accounts of the dependence at issue may appeal to relations of composition, supervenience, realization, grounding, or causation. Accounts of the autonomy at issue may appeal to fundamental or non-fundamental novelty of powers, properties, forces, laws, or effects; irreducibility; non-aggregativity; or non-linearity.