What is the ontological status of social entities -- kinship systems, police departments, religious movements? And what is the status of causal powers of social entities? Do we need to "reduce" social entities to the compounds of individuals who make them up? And do we need to derive the causal properties of social entities from the characteristics and interactions of the individuals who make them up? In short, do we need to be reductionist about the social world?This is a question that arises in many of the "special" sciences, including in particular psychology and neuroscience. A basic premise of contemporary philosophy is that all phenomena are composed of physical entities, processes, and systems. The mind-body problem...