Wednesday, September 17, 2014

Animals and Animalia

If tauntauns (i.e., creatures relevantly like this) existed, they would be animals. If tauntauns existed, they wouldn't be members of the kingdom Animalia, because the kingdom Animalia is a clade, and Tauntaun's would presumably be products of alien evolution rather than descendants of earth animals. Since it's possible for tauntauns to exist, it follows that it's possible for there to be animals that aren't members of the kingdom Animalia.

Another example. Suppose a species of water plant evolved to have descendants whose behavior and build closely resembles a hippotamus. The resulting species would still be a member of the kingdom Plantae, since the Plantae are a clade, and not of Animalia. But I think it would be an animal. Would it be a plant as well? Maybe—maybe it would be both plant and animal.

The concept of an animal goes beyond actual earth biology. Now, here's an interesting question. We are rational animals. Could there be rational embodied non-animals, e.g., rational plants that, unlike the hippopotamus-like plants of my example, are not animals? There would be little reason for a non-animal to evolve intelligence, but an extremely unlikely series of chance mutations is not impossible just because it's unlikely.

Are questions about what is and what isn't an animal substantive questions? Or is it just a matter of drawing arbitrary non-joint-carving boundaries?


Austin said...

It's an important question to ask if we think that something like Aristotelian Essentialism is true.

That's something that's always given me trouble with essences and formal causes in the Aristotelian sense. How do we determine what is what, when the lines seem so blurred (or in the case of your examples, confused)?

William said...

It's important here to keep a clear distinction between animal as a member of a a very old and big clade, the kingdom Animalia, and animal as defined by statements such as "it looks like a duck and quacks like a duck, so it must be an animal."

The first definition is based on historical pedigree and related datsa such as similarities in ribosomal DNA sequence, the second definition uses functional considerations alone.

I'd say the second definition makes far more error-prone assumptions than the first, but both can be used, especially since we usually have more access to information about function than pedigree.

William said...


Even if Aristeteliam essentialism were true, our classifications of species are still going to be error prone. The troubles for the Thomist are not in the fact that our classifications can be in error, but rather in the intolerance for error engendered by linking an error-prone empirical system to a theological system that eschews any suggestion of error.

It's hard to get an error prone biology, whether Aristotelian or modern, to support epistomological certainty about a doctrinal postition about the place of humans in the world. But that is exactly what some essentialists try to do.