On Words: II

My comment about the basics of evolutionary biology and how they enter into non-scientific discourse elicited this response from RPM:

You may not like the concept of speciation, but the parts that make it up (reinforcement, geographic isolation, pre- and post-zygotic barriers, etc) are real. They are also worth studying, imo. In studying those factors, scientists are, for all intents and purposes, studying "speciation". And to study speciation, we must come up with a definition for what we consider species. Coyne and Orr argue that the best definition (in terms of practicality when studying speciation in sexual organisms) is the BSC. I like this line of thinking, and seems appropriate regardless of whether you think species are real or not.

I enjoyed Speciation, and have only a few quibbles which Coyne and Orr's work. Fundamentally I don't disagree with RPM's comment, as I said, I'm an instrumentalist on the species concept debate. Fancy philosophical words do sometimes condense the meaning of several sentences, and that's why I use the word "instrumentalist." Follow the dictionary.com link if you don't know the term, because it gets the gist of my attitude across, by its fruits, you shall know it.

But there is a difference between science and rhetoric. Fixing specifically on the species concept, and the idea of species, while I see the utility of species in talking about science and systematically exploring the web of life and the processes which give rise to diversity, I think things get sketchier when I get into debates with Creationists. Creationists believe in "kinds," idealized separate types which are subject to "microevolution," but have been extant since time immemorial after the special creation. They have an interest in species and speciation because species are basically the equivalent of kinds. Once you start engaging a Creationist you will get into the minutiae of observed speciation, at which point you'll encounter someone who refuses to acknowledge that that really is speciation. I recall in one debate a Creationist responded to instances of speciation by stating "well, that's not a body plan change!" Getting into this speciation debate is like trapping yourself in quick sand as you attempt to counterattack everytime the Creationist moves the goal posts.

And those goal posts are movable because though they pretend that it isn't so, "kinds" are subjective, because "species" are subjective. That subjectivity and fuzzines does map onto a strong operationally discrete reality in many cases, but the fact that there is some continuity and ambiguity means that you can't ever pin Creationists down. They have their cake and eat it, you a) implicitly accept a hard concept of species ("kinds") by refuting them with observed instances of speciation b) at which point the Creationist takes control of the discourse by redefining species in whatever way suits them. This is where a pragmatic and instrumentalist attutidue gets you into trouble, because it isn't like you have really believe in hard & fast rules which you can leverage into rhetorical talking points, prior to this debate spieces are rough guides to real scientific questions. But once you leave science and enter religion, philosophy and politics this sort of instrumentalism and open-minded acceptance of fuzziness at the edge of concepts leaves an opening for your opponents to simply reshape the words to best forward their arguments.

But the issue is not just with Creationists. Many of the readers of my other weblog have been reading for a while now, but they still get into confusions regarding the basics of evolution. Terms like "species" often get in the way, as cognitive biases to see different "kinds" as "essences" crop up over and over. Species are a useful concept, but, without the underlying matrix of subordinate concepts (e.g., and understanding of mutation, drift, selection, etc., forms of mating isolation) you don't go much beyond intuition and man-on-the-street common sense. The point of my previous post was that instead of defending the territory that someone else stakes out, sometimes it is important to simply redefine the game to be true to what you are really getting at. To use an analogy with race, those who say "race does not exist" will often refute a typological/Platonic concept of race by pointing to gradual phenotypic change. I don't start with correlation structure and the statistical issues that are relevant, I disabuse the other individual of the notion that I do accept a Platonic conception of race in the first place! You simply can't dismantle the Creationist's house with the Creationist's tools.