ABSTRACT
It is common practice among biologists to attribute functions to biological traits. Examples abound: the function the vertebrate kidney is to purify the blood; the function of an image-forming eye is vision. Yet the concept of biological function is far from unproblematic. The explanatory role and the ontological commitments of functions have been the source of intense debate over the last thirty years or more. The issue is that, as intuitively appealing, as evidently instructive, as function ascriptions are they appear to deploy a mode of thinking that, by all accounts, has been thoroughly discredited since the Scientific Revolution. Function ascriptions, taken at face value, are teleological. A function ascription answers the question “What is it for?” where the answer to the question cites some effect that the trait ought to have for the good of the organism of which it is a part. Moreover, in a functional explanation, the appeal to “what a trait is for” is called on to explain the presence of the entity functionally characterized. The most vivid analogy for the role of functions in biology comes from the functions of artifacts. Artifact function is unreservedly teleological. The function of an artifact is determined by the intentions of the designer (or user). Much of the recent philosophical literature on function addresses this tension between the presumed explanatory role of function ascriptions, on the one hand, and their naturalistic credentials, on the other. Two general strategies for naturalizing function emerge from the recent debates. The first, by far the more common – I call it reductive non-teleological – attempts to recast the concept of function in a way that eliminates the apparent commitment to unreduced natural teleology. The second strategy – I call it non-reductive teleological – accepts at face value the teleological implications of function ascriptions and functional explanations. It attempts to demonstrate, nevertheless, that genuine teleological functions are naturalistically acceptable.
