In this paper, I try to develop an account of functions which might be of use to a biologist engaged in classifying and explaining natural phenomena. The most pressing difficulty facing such an account is the need to reconcile the normativity of function statements with their explanatory force. I consider two familiar accounts of function statements, offered by Andrew Woodfield (an ‘Actual Capacity Theorist’) and Larry Wright (a ‘Historical Theorist’). I examine both accounts in search of the strongest possible formulation of each type of theory. I fail to find a formulation of the ACT which is completely immune from counterexamples, but I do find a satisfactory formulation of the HT. In particular, I argue that the HT should incorporate a point central to the ACT that functions involve a means/end relationship between two devices. I then consider functional explanations: I argue that an ACT which holds that function statements are intrinsically explanatory cannot offer a satisfactory account. The account offered by Woodfield, who rejects this assumption, is adequate, though less attractive than the account suggested by the HT. I conclude by considering how the HT can account for functional norms. Copyright © 1995, Wiley Blackwell. All rights reserved
