Defending The Evolutionary Argument Against Naturalism (EEAN)

As part of a disagreement with philosopher Massimo Pigliucci on Rationally Speaking, I have found myself in the unusual position of having to defend Alvin Plantinga's Evolutionary Argument Against Naturalism.

As a firm proponent of philosophical naturalism, I do not find the EAAN to be persuasive. However, I feel that Pigliucci has treated the argument unfairly, glossing over the crucial point and picking at irrelevant details.

In this post, I will attempt to defend the argument and present it as persuasively as I can. In a later post, I intend to refute it.

Let's define:

• N as naturalism - in this context the idea that there is no such person as God or anything like God
• E as the belief that human beings have evolved in conformity with current evolutionary theory
• R as the proposition that our faculties are "reliable", where a cognitive faculty is "reliable" if the great bulk of its deliverances are true.

First, Plantinga explains why we should not expect creatures who have evolved naturalistically to be able to reliably form true beliefs, i.e. that the probability of R given E and N is very low. 

Now, if he's right about this (and I don't think he is), he is correct that naturalism becomes untenable. The argument is rather simple.

If we are unlikely to have the ability to form true beliefs, then none of our beliefs are reliable, and so neither is the theory of evolution itself, which is a product of those beliefs. So if you believe in naturalism, it is irrational to believe in evolution.

Plantinga's resolution is to accept evolution and to reject naturalism, as accepting naturalism while rejecting evolution is not tenable - there's no credible alternative to evolution and the supporting evidence is overwhelming.

All of this is fine as far as I'm concerned, once you accept his core premise.

The Core Premise of EAAN

P1: P(R|E&N) is low - (there is only a low or negligible probability that we have the ability to reliably form true beliefs, given philosophical naturalism and evolution)

Plantinga acknowledges four distinct possibilities regarding the interaction of beliefs and adaptive behaviours.

1. Beliefs do not affect behaviour.
2. The semantic content or meaning of beliefs do not affect behaviour, only their physical representation in the brain (which could potentially represent other meanings).
3. Beliefs tend to affect behaviour but are maladaptive.
4. Beliefs tend to affect behaviour adaptively, but can be true or false.

For each of these possibilities, Plantinga explains why P1 would hold.

However, I will only address the last, as it is the only one I deem to be plausible and compatible with philosophical naturalism.

Pigliucci presents the following premises, in my view correctly summarising Plantinga's assumptions.

1. Our beliefs about the world can only have evolutionary consequences if they affect our behaviors (otherwise they are invisible to natural selection);
2. Natural selection favors advantageous behaviors, not directly the ability to form true beliefs;
3. Natural selection has no way to favor true non-adaptive beliefs over false but adaptive beliefs.

So, it seems clear that beliefs have no direct bearing on evolution, only the behaviours that result. When we see an animal fleeing a predator, it doesn't matter why the animal thinks it is running away as long as it escapes to reproduce and pass on its genes. Any beliefs that produce this behaviour will be sufficient, and they need not be true.

The classic example Plantinga usually gives is that of an early hominid escaping from a tiger. We might expect, on witnessing this event, that the hominid is running away because it correctly believes the tiger will kill and eat it (and that it is a bad thing to be killed and eaten).

However a number of alternative false beliefs could have produced the same behaviour.

• It is good to be killed and eaten - however this tiger appears too weak. I should run away to find a more ferocious tiger!
• What a cute animal! I must approach it and pet it! Therefore, I shall run in the opposite direction, as this is the most efficient way to approach it.
• A tiger! The signal that the race has started! I must be quick if I am to win!
• What a happy day! A tiger! Everyone knows that it is good luck to see a tiger, but you have to acknowledge this by running away.
• It's a fearsome dragon! I must escape!

The possibilities are endless. There is only one true belief which will lead the hominid to escape, but limitless false beliefs. As evolution doesn't care what the hominid believes so long as it escapes, it seems improbable that it would happen to find the one belief out of the infinite possibilities that both happens to be true and leads to the correct behaviour. In fact, the probability that the homind has the correct belief would seem to be negligible.

And this is true in general. There is no situation where evolution would have preferred a true adaptive belief to a false adaptive belief, and so no reason to expect that a naturalistically evolved creature should ever form a true belief except as a case of extreme coincidence.

As such, though we should expect any naturalistically evolved creature to behave in an adaptive and apparently intelligent way, the reasons for these behaviours are likely be completely crazy, as there is no incentive for evolution to prefer sanity.

A belief that we have evolved in a naturalistic universe therefore leads inevitably to the conclusion that we are all insane, and all of our beliefs are probably inconsistent, random and untrue, while we remain oblivious to this and thrive regardless.

Plantinga then goes on as outlined above to defend our sanity by rejecting naturalism. This rejection makes tenable the position that we are sane, as some supernatural force may have intervened in evolution and selected for sanity rather than mere adaptability.

Defending P1

A common response to this argument, and that favoured by Pigliucci, is that evolution is not the only mechanism by which we have acquired the ability to form beliefs. Our millenia of civilisation have allowed us to develop sophisticated cognitive tools to overcome our evolutionary shortcomings. We have developed science, mathematics, philosophy and logic to augment our natural abilities, and these tools have proven to be reliable by the wonderful technologies they have allowed us to develop and the many correct predictions we have made about the natural world.

We did not simply evolve the ability to do quantum mechanics - we are genetically pretty similar to Cro-Magnon man but we are light years ahead in understanding and ability. These abilities have arisen due to the accumulated experience of countless generations of our ancestors, passing along ideas that work and discarding those that don't. There's more than natural selection at work - cultural evolution comes into play also, and cultural evolution does indeed favour true beliefs over false ones.

The problem with this argument is that all of the tools that we have acquired to help us form true beliefs can only be trusted if our biological inheritance of belief-generating apparatus is reliable. The ability to do quantum mechanics is certainly not innate, but the potential to learn and develop something so abstract - afforded by our instinctive intuitions regarding logic and truth - certainly is.

If we are profoundly deluded, then any system we have developed to help us cope with our delusion must also be suspect, no matter how convincing it appears to us. Any argument to the contrary is like a madman in an insane asylum insisting he is perfectly sane because the voices in his head tell him so.

There is no escaping this conclusion, as any argument to the contrary must necessarily depend on the rationality it seeks to establish. You can point at all of our achievements and claim that our track record shows our beliefs must be correct, but perhaps this conclusion simply isn't borne out by this evidence. We may be incorrect in all of our basic assumptions about logic and argument, or perhaps we have achieved nothing, and are merely dreaming of being masters of technology. No conclusion is possible if our innate rationality is in doubt, including the conclusion that the scientific method or our philosophical heritage have equipped us with the ability to form true beliefs.

In my view, P1 overcomes this criticism unscathed. In my next post, I'll attempt to defeat it with a criticism from another angle.