In this article I argue for an Aristotelian hylomorphic view of bodily parthood on which parthood turns on functionality: something is part of a human being's body just in case it functions in the right way for the sake of that person; that is, its functioning aims at the flourishing of the particular human's biological life. Thus, perhaps counterintuitively, some things can stand in the body part relation without being composed of human cells-say, transplanted non-human organs or prosthetic appendages. I argue that there is evidence that some functions of the human body are relational: body parts can perform social functions. If these social or relational functions are genuine functions of the human body, then parts that may not appear to be functioning are. I argue that this could have ethical implications for delineating surgeries that are "functional" versus "aesthetic" (and perhaps necessary versus elective), and implications for human enhancement.
Hilary Yancey (Wed,) studied this question.