Levels and explanations

It is a mainstay of the philosophy of science that reduction is a relationship between theories pitched at different levels of nature. But the relevant sense of “level” is notoriously difficult to pin down. A promising recent analysis links the notion of level to the compositional relations associated with mechanistic explanation. Such relations do not order objects by scale or physical type; one and the same kind of entity can occur at several levels in a single mechanism. I will sketch this approach to levels and consider some of its implications for our understanding of the relationship between cognitive psychology and neuroscience.Jon Opi