Infima species

There is a classic controversy in interpreting Aristotle: Is there one form per individual or one form per species?

One of the main arguments for individual forms is that the form of the human being is the soul, and it would be crazy to think that you and I have the same soul.

But what if—though this is surely not what Aristotle thought—the truth were this: There is one form per species, but humans, unlike other organisms, are each their own species (much as Aquinas thought the angels were).

This creates a discontinuity between non-human and human animals. This discontinuity is in itself a disadvantage of the view—it makes things more complicated.

However, at the same time the discontinuity would correspond nicely with some ethical intuitions. It wouldn’t be reasonable for a human to sacrifice her life for a Komodo dragon. But it could be reasonable for her to sacrifice her life for the Komodo dragon species. The view also fits with the widespread, though far from universal, intuition that it is permissible to kill non-human animals for food, but that the killing of a human being is a morally far weightier thing. Moreover, the idea that humans are infima species seems to capture important things about human individuality (I am grateful to Richard Gale for this observation), including the idea that while there is a teleological commonality between human beings, it is also the case that individual humans have individual vocations, telè that are their own only.

The main disadvantage of the view is theological. In Athanasian soteriology, it is crucial that Christ is metaphysically same species as we are. But one might hope that a Christology could be modified where being of the same genus would play the same role as being of the same species does for St Athanasius—or perhaps one where what plays the role is just the fact of a shared rational animality (which we also share with any non-human rational animals outside of the Solar System).

I don’t think the view is true, because the radical discontinuity the view posits between non-human and human animals just seems wrong. But I think there is more to be said for this view than is generally thought. And for those who think that they are not animals—for instance, people who think that they are constituted by an animal—the view seems even better.