Abstract

A persistent boast of the historical approach to functions is that functional properties are normative. The claim is that a token trait retains its functional status even when it is defective, diseased, or damaged and consequently unable to perform the relevant task. This is because historical functional categories are defined in terms of some sort of historical success -- success in natural selection, typically -- which imposes a norm upon the performance of descendent tokens. Descendents thus are supposed to perform the associated task even when they cannot. The conceit, then, is that malfunctions are explicable in terms of historical success. The aim of this paper is to challenge this conceit. My thesis is that the historical approach to functions lacks the resources with which to account for the possibility of malfunctions. If functional types are defined in terms of historical success, then tokens that lack the defining property due to defect, and tokens that have lost the defining property due to disease or damage, are excluded from the functional category. Historically based malfunctions, in consequence, are impossible. The historical approach is no better than its non-historical competitors in accounting for the presumed normativity of functional properties.