 The Boorsian analysis is of a commonsense concept of disease which bottoms out in a notion of malfunction as the cause of illness. The view is that conceptual analysis determines the empirical commitments of our disease concepts and then hands over to the biomedical sciences the problem of finding biological functions and malfunctions. Some recent theorists, notably Wakefield, have argued for an evolutionary account of function as that which has historically been spread by natural selection. Others have argued that the biomedical sciences employ a different conception of function. Besides identifying the right concept of function for the job, other problems affect the whole naturalist community. A reliance on scientific, functional decomposition as the ultimate justification of judgments of health and disease requires a revisionist, rather than a conservative, account. Also, it may not always be possible to settle contested cases by an appeal to a notion of normal human nature, because that notion is itself contested.