Wednesday, April 25, 2018

We aren't just rational animals

I think some Aristotelian philosophers are inclined to think that our nature is to be rational animals, so that all rational animals would be of the same metaphysical species. Here is a problem with this. Our nature—or form or essence—specifies the norms for our structure. Our norms specify that we should be bipedal: there is something wrong with us if we are incapable of bipedality. But an intelligent squid would be a rational animal, and its norms would surely not specify that it is supposed to be bipedal. So, it seems, that the hypothetical intelligent squid would have a different nature from ours.

But that was too quick. For it could be that our nature grounds conditionals like:

  1. If you’re human, you should have two arms and two legs

  2. If you’re a squid, you should have eight arms and two tentacles.

We have some reason to think there are such conditional normative facts even if we take our metaphysical species narrowly to be something like human or even homo sapiens, since presumably our nature grounds normative conditionals about bodily structure with antecedents specifying whether we are male or female.

But there is a hitch here: if humans and intelligent squid have the same form, what makes it be the case that for me the antecedent of 1 is true while for Alice (say) the antecedent of 2 is true? I think our best story may be that it is facts about DNA, so in fact the antecedents of 1 and 2 are abbreviations for complex facts about DNA.

That might work for DNA-based animals, which are all the animals we have on earth, but it probably won’t work for all possible animals. For surely there nomically could be animals that are not based on DNA, and it is implausible that we carry in our nature the grounds for an array of conditionals for all the nomically (at least) possible genetic encoding schemes.

I suppose we could take our nature to be rational members of the Animalia, with the assumption that the kingdom Animalia necessarily includes only DNA-based organisms (but not all of them, of course). But Animalia seems a somewhat arbitrary choice of classification to tack on to rationality. It doesn’t have the exobiological generality of animal, the earthly generality of DNA-based organism, or the specificity of human.

It seems to me that

  • rational DNA-based organism, or

  • rational member of genus Homo

are better options for where to draw the lines of our metaphysical species, assuming “rationality” is the right category (as opposed to, say, St. John Paul II’s suggestion that we are fundamentally self-givers), than either rational animal or rational member of Animalia.


William said...

Does "metaphysical species" really mean species, or this a situation like "fictional woman" not really meaning woman? Does the question of what Lady Macbeth's fingerprints are make sense? Does a squid being the same species as a human if the squid is intelligent make sense?

Christopher Michael said...

Here's a not unreasonable way to bite the bullet: in fact, the form of the human body prescribes not just rational animality but also all the features of Homo sapiens, such that if God infused such a form into an octopus, that octopus would change into a member of Homo sapiens. And this explains why God would never infuse such a soul into anything but a member of Homo sapiens (i.e. a descendant of Adam). It also would explain why God waits until He does in evolutionary history to infuse the rational soul (the matter has to be properly disposed).

Alexander R Pruss said...


I take this proposal to be a way of denying that our nature is just rational animality. It includes rational animality, but it additionally includes all the other features of Homo sapiens. I personally like something pretty similar, except that I see no reason to tie it to that low a level of species. I think there is a good chance we should include Neanderthals as well. (Some relevant evidence: )


The metaphysical sense of species comes from Aristotle, and hence it has long predated the modern biological gene-exchange sense. So I think it would be odd to say it's not really a species concept.

I think a squid being the same species as a human if the squid is intelligent *could* make sense: we could imagine that they are fundamentally the same kind of thing, despite very different body plans (just as you and I are fundamentally the same kind of thing, despite *somewhat* different body plans). It depends whether the mentality is more important for classification than body plan.

Ganesh Bharate said...

First of all Aristotle also made a statement "Man is a social animal". Secondly Genidentity is getting older and unfashionable. We have much more better concepts like Holobionts or Symbionts. What is problematic according to me is the essentialist conception of universals. Aristotle inherited some form of essentialism from Plato. To resolve this issue we have to go to Heraclitus, Whitehead, Rescher or Buddhism and seek some form of non-essentialism.

Alexander R Pruss said...

I think we need universalism (as well as metaphysical species) to make objective sense of defects, a concept we need for ethical purposes.

William said...

Yes, good point about the ethical purposes of these questions.

The problem with using descriptive labels that classify species, as Aristotle does with the "rational animal" category, is that it depends entirely on the way that the "intension" or abstract set definition of the species is designed to correspond to the extension of an empirically sensible grouping of real living things in the real world, with that extension consisting of living things that are historically connected by some sort of kinship lines. Imaginary creatures can really distort that carefully crafted intension-extension correspondence.

I like the idea of planning to define other intelligent beings that we might find in the future as _legally_ or _socially_ human, since it might avoid ethical mistakes in how we treat them. But any such beings would generally not be in our clade. The real, genuine kinded history of an intelligent being matters in biology for species classification, and thought experiment animals don't have that history.

To put things in an old context, Augustine says in,
"Wherefore, to conclude this question cautiously and guardedly, either these things which have been told of some races have no existence at all; or if they do exist, they are not human races; or if they are human, they are descended from Adam."

I'd say that in real life, an intelligent squid would either be have been made by us via a fusion with human DNA, in which case it is in a malformed way "descended from Adam," or, as Augustine said, "if they do exist, they are not human races."