 A critic might concede that we in fact hold these divergent attitudes toward humans and non-human animals but would question their moral significance: why should we regard the congenital absence of certain capacities as a tragedy for the individual lacking them if and only if that individual is human (McMahan 1996)? A humanist would respond that the question itself reveals that the critic simply is not clear on the concept of “human being”—a concept that includes the notion of a common life, based on shared embodiment, from which radically impaired humans are excluded.