 A second argumentative strategy in defense of the higher-brain approach claims to appeal to our personal identity while remaining agnostic on the question of our essence (Green and Wikler 1980). The fundamental claim is that, whatever we are essentially, it is clear that one of us has gone out of existence once the capacity for consciousness has been irreversibly lost, supporting the higher-brain standard of death. Clearly, though, any view of our numerical identity over time—our persistence conditions—is conceptually dependent on a view of what we essentially are (DeGrazia 1999; DeGrazia 2005, ch. 4). If we are essentially human animals, and not essentially beings with psychological capacities, then, contrary to the above argument, it is not clear—indeed, it is false—that we go out of existence upon irreversible loss of the capacity for consciousness; rather, we die upon the collapse of organismic functioning. The appeal to personal identity in support of the higher-brain standard depends on the thesis that we are essentially minded beings and therefore inherits the challenges facing this view, as discussed in the previous subsection. Nevertheless, the appeal to personal identity, construed as a distinct argumentative strategy, was somewhat influential in early discussions of the definition of death (see, e.g., President's Commission 1981, 38–9).