 At present, the nature of conceptual structure remains unsettled. Perhaps part of the problem is that more attention needs to be given to the question of what explanatory work conceptual structure is supposed to do and the possibility that there are different types of structure associated with different explanatory functions. We’ve seen that conceptual structure is invoked to explain, among other things, typicality effects, reflective categorization, cognitive development, reference determination, and compositionality. But there is no reason to assume that a single type of structure can explain all of these things. As a result, there is no reason why philosophers shouldn’t maintain that concepts have different types of structure. For example, notice that atomism is largely motivated by anti-descriptivism. In effect, the atomist maintains that considerable psychological variability is consistent with concepts entering into the same mind-world causal relations, and that it’s the latter that determines a concept’s reference. But just because the mechanisms of reference determination permit considerable psychological variability doesn’t mean that there aren’t, in fact, significant patterns for psychologists to uncover. On the contrary, the evidence for typicality effects is impressive by any measure. For this reason, it isn’t unreasonable to claim that concepts do have prototype structure even if that structure has nothing to do with the determination of a concept’s referent. Similar considerations suggest that concepts may have theory-structure and perhaps other types of structure as well (see Laurence &amp; Margolis 1999 on different types of conceptual structure). 