  If moral status admits of degrees, then the defender of animal research would locate the main problem with the Borderline-Personhood Argument in its claim that there are only slight differences in personhood-relevant properties between borderline persons and paradigmatic persons. In fact, the differences between even a language-trained chimpanzee and a normal adult human are quite large. As DeGrazia himself argues elsewhere, for example, only normal adult humans are capable of what he calls “full-fledged moral agency” (1996, 199–210). Now, the Borderline-Personhood Argument only requires that borderline personhood be sufficient, not necessary, for full or near-full moral status, but both the Unequal Consideration Model and the Unequal Interests Model quite generally relate moral status to personhood-relevant properties. The question therefore arises as to why these vast differences in personhood-relevant properties do not underwrite a large difference in moral status and a concomitant difference in the research protections owed to individuals of the two groups.