ABSTRACT
The concept of “function” is used in science to ask two types of questions: The first asks what the external function of some particular structure might be or, equivalently, what external function some particular structure might serve. The second usage asks how a particular structure functions, or equivalently, what internal relationships among the parts of a structure account for its capacity to serve the external functions which it does in fact serve. We might, for example, ask either what function the human hand serves (i.e., in what way it affects the interaction between an individual and his or her environment), or, how the human hand functions (i.e., what internal processes make it possible to serve that function).
