 There is, then, a perspective on humans that is plausibly present in Aristotle, stronger in Aquinas and dominant in Kant and that involves seeing them as instances of a kind other than the “human kind”, i.e., seeing the human animal “as a rational being” (Kant 1785 [1996: 45]). According to this view, the “nature” of humans that is most worthy of philosophical interest is the one they possess not insofar as they are human, but insofar as they are rational. Where this is the relevant use of the concept of human nature, being a specimen of the biological species is unnecessary for possessing the corresponding property. Specimens of other species, as well as non-biological entities may also belong to the relevant kind. It is also insufficient, as not all humans will have the properties necessary for membership in that kind.