Two Kinds of Biology

I'm leading a discussion of a paper on Monday that I find rather difficult, so I'm going to write down some thoughts about it here. It's called "Organisms as natural purposes: the contemporary evolutionary perspective", by D. M. Walsh in the 37th volume of Studies in History and Philosophy of Biological and Biomedical Sciences. This paper actually meshes well with some other reading I've been doing, including Dawkins' book (which I've already commented on a few times) and a book by Kirchner and Gerhardt called The Plausibility of Life. The argument goes like this: Kant described a paradox of sorts when he said that mechanical law is the only natural explanation; but organisms are natural purposes and thus inexplicable by mechanical law. I trust that the first half of the paradox is familiar territory. The second half takes a bit of explaining, and I find that I have trouble understanding it - perhaps because it is inherently more difficult to graph, or perhaps because it is largely ignored or even denied in modern science (that's not my claim, it's Walsh's, although I think I agree with him). Think of it like this: Mechanical laws are like lines of code in a computer program. Each line tells the computer to carry out a certain operation (say, add some number n + 1). By the time the program is done running, the output is the number 213. Now this computer is built in such a way that if a number other than 213 +/- 5 is ever output by any program, the program will crash, the computer will freeze, and you will never get the data off of its hard drive. If the number is 213 +/- 5, the computer will duplicate itself (never mind how). During duplication, the program may inadvertently get changed - say, one of its n + 1 lines gets deleted. If the program outputs a number more than 3 away from 213, the computer has a 95% chance of responding by adding or subtracting an n + 1 line, as appropriate, to bring the output closer to 213. Over time, the computer population will be very stable, because the computers are able to "fix" themselves, even though the program in each computer might be slightly different (one might output 213, another 212, another 214, etc.; one might reach 212 by adding 1 + 1 + 1 + 1 + ..., whereas one might arrive at it by 1 + 1 + 1 + ... + 1 - 1 + 1, etc.). This variation can then be "naturally selected" if, say, computational efficiency is the desired trait; or if showy complexity is the desired trait. Sound like evolution? But there's a problem... The program not only is modified by the computer (by adding or subtracting n + 1 lines), but simply will not run without the computer! In order for the program to do anything - even for the program to exist - the computer must first be there to write and save and interpret and execute the program. This is what it means for a computer to be a natural purpose.

Now, let's turn to biological evolution. You have organisms which are like computers; you have genes which are like programs. All the other relations between computers and programs correspond to relations between organisms and genes. But the notion of a natural purpose is not much in vogue in the sciences. The general conviction is that nature is reductionistic, that the whole can be described in terms of the parts and that the parts are self-evident. This is Dawkins' view of evolution by natural selection. But there is apparently a rising tide of organisms-as-natural-purposes, coming from the developmental biology world. This is the position that Kirchner and Gerhardt take. Put in rather different terms, the generally accepted picture of evolution fits in the "mechanical laws" category; and the "natural purposes" category might be thought of as occupied by Intelligent Design. Hmmm... We come to this dichotomy again. Of course, I think that most people dealing with organisms as natural purposes are not thinking in terms of ID - rather, they are trying to put the natural purposiveness of organisms into a broader naturalistic picture. I'm not convinced that this is possible, but in the meantime there's some interesting stuff coming out of that group.

But what about Intelligent Design? In other entries I have come out rather negative toward ID. But I wonder... Would a modified form of ID be on stronger ground if it related itself directly to these kinds of issues?

Well, I'm not finished re-reading this paper, and my comments here take me about as far as I can go right now. I find it useful to write out my thoughts - it helps me to organize them in my own mind. And I think this entry is no exception to that rule. Phew! :-)