As one-time student of philosophy, I’m always happy to see it pop up in my non-academic life. So thanks to Jon Christensen for pointing to this short essay about species in Philosophy Today.

But I found it somewhat befuddling. The question on hand is, "what exactly is a species?" Geneticist Massimo Pigliucci says this:

… a recent count by R.L. Mayden lists a whopping 21 different concepts of species proposed in the literature! Part of the problem is that biologists (and some, but not all, philosophers) keep adopting an essentialist concept of species: there has to be one right way to think of the problem, and hence one unique solution, which we would surely find if only we had more data (say biologists) or thought a bit harder (say some philosophers).

I’d say you would be hard pressed to find any professional philosopher, analytic or continental, espousing an essentialist view of this or any other empirical concept. What shocked me is Pigliucci’s contention that most biologists do still hold such views. I would have thought that Darwin himself put the idea forever to rest.

Essentialism, with regard to species, asserts that nature is divided into discrete categories, each species with its own intrinsic nature (or essence). The biologist’s job, then, is to discover those dividing lines and accurately describe them — thus producing the True Taxonomy, the one that corresponds to nature. One can find essentialism at its most raw in Christian creationist lore. God created the species, assigning them their traits and characteristics, and there they remain today, unchanged. A more modern essentialist might, I suppose, find essences in genetics: to belong to species X is to contain gene X (or some combination of genes).

Suffice to say, this effort to find bright, unambiguous, universally acknowledged lines of separation in nature has failed. I just find it odd that biologists still conceive themselves as involved in that kind of project.

Pigliucci cites Wittegenstien as offering an alternative. Poor Ludwig is always trotted out for this purpose, but one might just as well turn to virtually any philosopher in the post-logical-positivist era. My favorites were the pragmatistsDewey and his many, varied heirs. They would say on this matter that we do not discover but decide how to divide the species, and do so based on what works best for our purposes.