 Before turning to other theories of conceptual structure, it’s worth pausing to see what’s so appealing about classical or definitional structure. Much of its appeal comes from the way it offers unified treatments of concept acquisition, categorization, and reference determination. In each case, the crucial work is being done by the very same components. Concept acquisition can be understood as a process in which new complex concepts are created by assembling their definitional constituents. Categorization can be understood as a psychological process in which a complex concept is matched to a target item by checking to see if each and every one of its definitional constituents applies to the target. And reference determination, we’ve already seen, is a matter of whether the definitional constituents do apply to the target.