Artifacts are not ascribed essences, nor are they treated as belonging to kinds

We evaluate three theories of categorisation in the domain of artifacts. Two theories are versions of psychological essentialism; they posit that artifact categorisation is a matter of judging membership in a kind by appealing to a belief about the true, underlying nature of the object. The first version holds that the essence can be identified with the intended function of objects. The second holds that the essence can be identified with the creator's intended kind membership. The third theory is called "minimalism". It states that judgements of kind membership are based on beliefs about causal laws, not beliefs about essences. We conclude that each theory makes unnecessary assumptions in explaining how people make everyday classifications and inductions with artifacts. Essentialist theories go wrong in assuming that the belief that artifacts have essences is critical to categorisation. All theories go wrong in assuming that artifacts are treated as if they belong to stable, fixed kinds. Theories of artifact categorisation must contend with the fact that artifact categories are not stable, but rather depend on the categorisation task at hand.