Why do zebras have stripes? One way to answer that question is ask what function stripes play in the lives of zebras – for example, to deter disease-carrying flies from biting them. This notion of a function plays a central role in biology: biologists frequently refer to the functions of many traits of evolved organisms. But not everything a trait causes is its function – the stripes might disorient some harmless birds, but that isn’t their function. So what determines the function of a trait? And what sort of explanations are offered when biologists claim that a trait has a particular function? In What Biological Functions Are and Why They Matter
(Cambridge University Press, 2019), Justin Garson
defends his generalized selected effects theory of what functions are and what they do. Garson, who is an associate professor of philosophy at Hunter College/CUNY, argues that functions can result from differential retention as well as differential replication in a population, and that to refer to a trait’s function is to provide a condensed causal explanation. This accessible introduction to debates regarding functions in the philosophy of biology also considers how the generalized selected effects theory contributes to contemporary debates in philosophy of psychiatry and philosophy of mind.