 A defender of a human kinship approach might readily accept this limitation, especially since we and the Martians would still be constrained by the attachments of the cognitively normal members of the other species to their radically impaired relations (as discussed in  Sec. 4.2  above). But she would still have to defend the claim that co-membership in the species established the sort of kinship that required even this species-relative full moral status. McMahan (2002) argues that even if membership in some groups, like nations, could confer full and equal status on its members, membership in the same species could not: