Emergence
This chapter surveys contemporary theories of emergence and argues that no comprehensive account currently exists. It separates ontological emergence, epistemological emergence, and conceptual emergence, as well as discussing synchronic and diachronic forms of each. It further argues that the emphasis on emergence in the philosophy of mind has led to a neglect of diachronic emergence and that the contrast between reduction and emergence has reinforced that bias. Downward causation is assessed as being less of a problem for ontological emergence than usually supposed; recent presentations of weak emergence and of undecidability results are discussed. Universality and nonlinearity as sources of emergence are examined, as is the role of holism in emergence and skepticism about the existence of emergence. Finally, a tentative suggestion is made about how to bring order to this vast literature.