Why believe our minds work, on atheism?

Part 6 in 20 atheist answers to questions they supposedly can’t

9. How is independent thought possible in a world ruled by chance and necessity?

Short answer: I’ll tell you once you’ve finished beating your wife. (Evolution selects for truth-directed faculties, so it is no surprise we get them on naturalism).

Longer answer: The argument here is twofold. Firstly, that atheism cannot account for our sense of having independent thought (and so this is evidence against it), and secondly that ‘independent thought’ is some pre-requisite for having justified beliefs, and naturalism undermines that. The first line of argument I’ll deal with consciousness and free will later. The second argument is a not-very-strong version of the evolutionary argument against naturalism. So let’s talk about that instead.

I doubt many naturalists really buy into the ‘chance and necessity’ recipe. If the laws of nature really are deterministic, there is no real  chance at all. We may assign odds of half/half that the coin turns up heads, but in reality the coin will turn up heads or tails according to the laws of nature, just we don’t know which one. But never mind that, what about this?

But how could this be so if the thoughts in our minds are nothing but electrical currents flowing through neuronal circuitry?  Would this not mean that our thoughts themselves are simply programmed and determined by physical laws? And would this therefore not also include the very thought that our thoughts are nothing but electrical currents flowing through neuronal circuitry? And if so how can we be sure that this thought, or any thought for that matter, are in fact true?

The idea is something like this: why should we expect our physical brains to return right answers? The main person who has run these sorts of concerns is Alvin Plantinga in the Evolutionary Argument Against Naturalism.

Plantinga’s older line of argument was to say it is very unlikely given our evolutionary past and naturalism we would end up with faculties that generally worked – that would lead us to generally think true beliefs (P(R|N&E) is low). So that we do have reasonable faculties is either (weakly) evidence against naturalism&evolutionary stuff, or an undercutting defeater, as if R is false our belief that N&E is unjustified with all our other beliefs.

There are only so many ways our beliefs could be related to the actual electrophysical goings-on in our brains, and whichever one turned out to be true would be bad news for naturalism:

1. Beliefs are not causally connected with behaviour. That is obviously bad news, as our brain could evolve just fine whilst our minds think anything at all. So it would be ludicrously unlikely our belief content would just happen upon the truth.
2. Beliefs are either effects of behaviour, or common effects with behaviour of other causes (epiphenomenalism). This is also bad news, as there seems no reason to think true beliefs need be ‘linked up’ in any way to survival behaviours.
3. Beliefs cause behaviour by syntax, but not via semantics (semantic epiphenomenalism). In other words, the particular neurons firing that ‘mean’ some proposition might affect my belief, but the actual meaning is irrelevant – all that is salient is the neurons firing. This again is bad news because proposition content is dissociated from behaviour – so long as my neurons fire in the right way, I survive, even if they code for false beliefs.
4. Beliefs do cause behaviour in virtue of their semantics, but true beliefs are maladaptive. Again bad news, as we should expect false beliefs, not true ones, as these are at a survival advantage in our evolutionary history.
5. Beliefs do cause behaviour by virtue of their semantics, and are adaptive. Plantinga argues this is false, because false beliefs can give rise to adaptive behaviour just as surely as true ones.

In a way, you can read this as Plantinga as winnowing down the options naturalist can take (“So you need to say beliefs have a causative role in behaviour, and they have to be causative in their semantics too, and they have to be adaptive. And that’s just not plausible!)

Generalizing horribly, the weak link that critics have tried to exploit is the claim that false beliefs are as likely to be adaptive as true ones. Plantinga supports it be saying that for any true belief that leads to a behaviour, we can imagine false beliefs that lead to the same behaviour (e.g. Jones thinking a tiger loves him but wants him to run away, that trees are witch-trees, etc.) The problem is that this isn’t enough. For true belief seems a much more robust way of mapping behaviour onto stimuli in a way that helps for survival: if I belief that Tiger’s want to kill me, I can reason to other beliefs that might advantage me. Leaping between false beliefs in the same manner that optimises survival is much less likely.

The reply then can be just to repeat the problem: for any true (survival enhancing) belief that leads to another true (survival enhancing) belief, we can think of false beliefs that engender other false beliefs that promote survival. Yet this seems a bit less likely – true beliefs are much more ‘survival fecund’ than false beliefs: a true belief seems much more likely to be adaptive than a false belief than a false belief (even if there are many false beliefs that would). So systems that lead us from true beliefs to true beliefs are far more likely to be adaptive than those that give false to false.

Of course, there will be such concatenations or systems of false beliefs that are just as adaptive than the truth. However, natural selection doesn’t act across the space of all conceivable possibilities, but the space of all accessible possibilities. So although our true adapted systems are pretty accessible (especially if semantic content is build up from simpler primitives like sensory organs), the false ones are much less easy for natural selection to find. So atheism probably has resources to deal with this.

Further reading

Plantinga’s books (Warranted Christian belief, Warrant and proper function) and Naturalism Defeated? cover most of the contemporary ground. In terms of things you can click on now, try this paper.

Depressingly, there is no STEP article or magisterial overview I could find online. Google away instead!