 Another difficulty—even if a given social category is the product of agreement—is identifying which feature of an agreement does the “metaphysical labor” in setting up the category. Suppose we employ a social category at time t′ which was a product of an agreement at time t. It may be that the features of that category are a product of the mental states of participants at t, or of the utterances or acts of participants at t. Or perhaps what matters is the mental states of community members at t′: that is, it is the synchronic trace of the agreement that sets up the social categories in a community at t, not the agreement itself.