How Not to Be a Darwinist

by Brian on July 2, 2004

I’ve been reading Christopher Peacocke’s “The Realm of Reason”:http://www.amazon.com/exec/obidos/ASIN/0199270724/caoineorg-20?creative=125581&camp=2321&link_code=as1, and I was rather struck by one of the moves in it. Unless I’ve really badly misinterpreted what he says in Chapter 3, he thinks you can come to justifiably believe in, and perhaps even know the truth of, theories of natural selection by looking really hard at a kitchen table and reflecting on what you’re doing.

First a little background. Peacocke is a rationalist and a foundationalist. He thinks that whenever you have a justified belief, its justification can be grounded in a chain of rationally acceptable transitions which bottom out in either conscious states or a priori knowable truths. Moreover, the transitions have to be (a) justifiable a priori and (b) have their justified status explained in part in virtue of the contents of the states involved in the transition. There are many problems for this position, the salient one being how do we ever get to know that the external world is anything like how it looks, given such meagre stuff to work with.

Descartes famously appealed to God at just this point. We can tell a priori (via the ontological argument) that a benevolent God exists, and He would not let us be massively deceived. Hence we are a priori justified in going from “That looks flat” to “That is flat”.

In keeping with the spirit of the age, Peacocke replaces God with Darwin. We can justify the transition because we’re probably evolved by natural selection and that means (probably) that we were selected for having accurate representations at least of certain fundamental things. Now as it stands this all seems pretty reasonable, but remember Peacocke is a rationalist. The justification has to work a priori. The mere fact that we’re evolved won’t do it. This is where the tables come in.

The table I’m looking at now has straight edges and round corners. Or at least so it looks to me. That is, I represent straightness when I look at its edges, and roundness when I look at its corners. What explains how I could be the kind of creature that has the capacity for spatial representation? This is a surprising, as Peacocke says Complex, fact and it cries out for explanation. Some say God’s handiwork explains my representational capacities. Others say a mad scientist. But the simplest explanation, says Peacocke. is that I’m the product of a process of natural selection. Unlike the other explanations, this does not need to appeal to representational capacities to explain representation. So _a priori_ we can tell the best explanation of representational capacities is natural selection. And since accurate representations are selected for, we probably get basic things right most of the time.

This is pretty ingenious, but there are at least three things you could say against the argument.

First, it isn’t clear in just what sense natural selection is a particularly simple explanation of the existence of representation. The amount of complex interactions needed to generate a selective process is rather staggering compared to what you need to mirror nature.

Second, inferences to the best explanation should consider all possible explanations, not just the ones that are current in the philosophical literature. And I don’t see why natural selection does best among all possible explanations at explaining the existence of representations. For instance, the hypothesis of a young earth created by a miracle with creatures with representative capacity seems to avoid some of the messy details of evolutionary theory.

Third, no practicing biologist would seriously consider arguing for natural selection on the basis of careful reflections about tables. If they did, there would be a lot more to complaints that natural selection isn’t better supported than creationist fables and hence doesn’t deserve pride of place in schools. Maybe we shouldn’t be completely deferential to scientists, but this kind of consideration seems to have some force to me.

I have quite a bit of sympathy for Peacocke’s overall rationalist program, but this part of it (and it’s a big part) really needs repair and/or replacement.

{ 7 comments }

1

rilkefan 07.02.04 at 5:44 am

“For instance, the hypothesis of a young earth created by a miracle with creatures with representative capacity seems to avoid some of the messy details of evolutionary theory.”

Whence the Complex creator, one might ask. And what’s messy about evolutionary theory beyond discrete genetic inheritance?

I totally don’t follow your third point. Isn’t Peacocke trying to give the equivalent of an existence proof, which while not as good as a constructive proof is not therefore wrong?

2

Chris Bertram 07.02.04 at 9:29 am

We can justify the transition because we’re probably evolved by natural selection and that means (probably) that we were selected for having accurate representations at least of certain fundamental things.

I have to say that I’m not especially happy with this part of the argument as it stands, though some work on what is involved in “accurate representation” might patch things here. Bees, bats, lizards and vultures are all naturally evolved creatures, and yet the way the world is to me and is to one of those creatures will probably differ very significantly. So to the extent to which “X is a an accurate represention of W” and “Y is an accurate representation of W” carries some implication of similarity between X and Y there looks to be a problem. Furthermore, it is far from obvious that natural selection favours accurate represention anyway, as well-known examples of cognitive bias attest.

Extra bit, which I should have integrated above and which may help with the way in which different creatures represent the world: you move from “how do we ever get to know that the external world is anything like how it looks” to a notion of “accurate representation.” But (see Nelson Goodman passim) an accurate representation of something needn’t be anything like that something: a map or a diagram can accurately represent that of which it is a map or a diagram without looking anything like what it represents (of course, you know that).

3

dave heasman 07.02.04 at 10:19 am

I don’t like the overall argument, if only because it begs the question of the origin of the theory of Natural Selection – we’ve been Naturally Selected to discover & believe in Natural Selection – apart of course from Them That Don’t, who might, come to think of it, have emerged Some Other Way.
And, as I’m not a philosopher (you noticed?) this puzzled me “The amount of complex interactions needed to generate a selective process is rather staggering compared to what you need to mirror nature”

But isn’t “generating a selective process” a very small component part of the activity of “mirroring nature”?

4

enzo rossi 07.02.04 at 11:31 am

I’ve only got rather vague recollections about this, but isn’t Peacocke’s argument quite similar to the evolutionary argument in Nozick’s The Nature of Rationality?

5

q 07.02.04 at 12:11 pm

_And since accurate representations are selected for, we probably get basic things right most of the time._

A fundamental misinterpretation of the theory of Natural Selection is to assume that becuase something currently exists, it represents the “best of kind”.

The existence or non-existence of natural selection cannot be used to demonstrate any existing fact or phenomenon. NS simply explains how patterns of processes can develop over time.

If stupid forgetful shortsighted people make more babies, we end up with a stupid shortsighted forgetful race.

6

john c. halasz 07.02.04 at 12:48 pm

That fellow is apparently aptly named, since all his eyes are on his tail feathers.

7

Peter 07.02.04 at 2:34 pm

I would like to refer you to Wolfram’s A New Kind of Science. He argues rather simply that simple rules can create very complicated systems, and that making the rules more complicated does not necessarily make the end result more complicated. Rather than using logic to sway the reader, he shows how to make your own simulations to show your self how it works.

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