From the series: 6 Ultimate Reasons Not To Be An Atheist?
#4 To be an atheist you cannot believe that you can trust your reasoning
The argument is two-fold. The first part is that all we are is blind chemical forces. The second part is that evolution is not a solution as evolution breeds for survival and not for rationality. The first part again is greedy reductionism and has been dealt with in Part 2: Morality, so it won't serve to dwell on it further. The second part is far more interesting and touches on Plantinga's Evolutionary Argument Against Naturalism. It is that argument which is interesting and there is much to be said for it.
The challenge of the EAAN is this, that natural selection doesn't select for beliefs themselves, it can only select for behaviour of beliefs. If a belief itself gives the right behaviour towards survival, then the truth of the belief doesn't matter. A true belief and a false belief that both give the same behaviour give the same result.
Consider the case of a child who is told to eat his vegetables. The first time he is told that eating his vegetables is good for him. He doesn't like the taste but does so on the belief that it will be good for him. The second time he is told that if he doesn't eat his vegetables he will burn in hell for eternity. He again doesn't like the taste but eats them on the fear of eternal punishment. In both cases the same behaviour that tends towards survival, so there is no difference between the truth (overall health) and the falsehood (eternal punishment).
Thus since multiple beliefs give the same behavioural outcome, it cannot be taken that the true belief is reliable because all it can confirm is that it is a potential truth that gives the right behaviour.
So to ask the first question, is it necessary? And finally I'm going to answer that yes it is necessary. It seriously undermines the atheist position if they have no ability to determine with confidence anything about the reality we reside in. It really is a defeater argument as Plantinga puts it. But beyond the conceptual, it's pertinent to point out just what needs to be explained.
Firstly it needs to be explained as to the evidence from the ascent of man. That is to explain tools, cave paintings, fires, domestication of animals, agriculture, civilisation, technological advancement, etc. What humans have achieved, because whether there is a god or not where we find ourselves now and what we find in our past remains the same.
Secondly it needs to be explained as to why there are so many different contradicting beliefs out there. Why some people believe in one god, why some believe in many, why some believe in ghosts, or spirits, or psychic powers, or electromagnetic theory, or gravity, or a geocentric universe, or anything else for that matter. In other words, so many contradictory beliefs out there that any explanation has to account for why so many have wrong beliefs.
Thirdly it needs to be explained how one can distinguish between true and false beliefs. This one is the clincher, for it is not enough to offer a means by which a belief could be given as true. And since there are so many false beliefs out there, how can one distinguish between what is a true belief and what is a false belief?
Okay, so for a theist how do they get around their own defeater argument? Well revelation could be one answer. But revelation doesn't pass the third criteria, for even if revelation were real how would we be able to distinguish between revelation and poor reasoning? This is the problem of claiming revelation, for even if it were really a god and really a good god, it still wouldn't be able to be distinguished - because merely being convinced isn't enough.
Another possibility in conjunction with revelation is that a good god intervened in the evolutionary process in order to allow us to gain true beliefs. But again this fails, this time because it fails to explain why there are so many false beliefs out there. Why was it that the Mayans sacrificed virgin girls to appease the sun god? Why is it that many now are convinced that not only psychic powers exist but that they have them? The fact that there are so many contradictory beliefs rejects this notion.
What could be the clincher is that we didn't evolve, but were created. This way we were created in almost perfection, and it was the fall resulting from eating from the tree of knowledge. It can account for why there are so many false beliefs out there, but still it fails because it means we can't know that it's true. the story is consistent, but it fails to break away from the problem of not being able to discern between true beliefs and false beliefs.
Furthermore the creation solution conflicts with all empirical data. If creation were true and the story of the fall being true, then why does all the empirical evidence suggest otherwise? Why is there a progressive fossil record in the ground? Why are there fossil genes and pieces of genetic code? Why is it that observations of the speed of light being constant extrapolate to measurements of distant galaxies being billions of light years away? Either we can't trust our senses and reasoning capacity, or creation doesn't fit with the evidence.
If Plantinga's argument is valid, then it is theism that is in trouble. One can't simply destroy our ability to reason without destroying one's own position. For it follows that if there was a good god then we should be able to trust our sense data and reasoning processes. But because our sense data and reasoning processes by those who study the natural world clearly point to evolutionary origins, then one has to conclude that evolution in some capacity can shape both the sense data and reasoning processes.
So how can evolution build a solid foundation for epistemology? Evolution selects for survival, this much is true. But survival is not simply reproduction of the genes. To think of what we as a social species has to do: be able to navigate the environment, avoid being killed / eaten, find a mate, interact socially, cooperate with others, raise children, etc. In any case, while survival of the genes is as far as one can reduce the process to, natural selection has built a vast array of structures to help facilitate that exchange.
It's been well established that evolution can build structures like eyeballs. But what good is an eye without the ability to process the information? To think of it another way, what good is a security camera without a means to see the input. One need to capture input and process it in such a way that would enable the survival. Without doing such, evolving a processing unit or an optical device would both be useless on their own.
So evolution is going to not only select a better eye, but select a brain that can use that input to elicit an appropriate response. In effect, we get mostly accurate senses not from having the organs alone, but a means to process the electrical impulses in a manner that makes the environment make sense. It gives a survival advantage, not just survival.
So what of beliefs? It should be established above that evolution can give us mostly reliable sense data as it would confer a survival advantage. But beliefs themselves aren't encoded into our DNA, thinking processes are. For instance, babies have an innate sense of gravity. They also have an innate sense of agency. And evolution-wise, both are essential. It's no accident that our visual range corresponds with the peak output from the sun's black body radiation. Just as it's no coincidence that we are wired to detect gravity or agents in the world.
So what of beliefs? Well there are the beliefs we form about the world through experience that correspond with what we see and measure. Some of these beliefs are testable here and now, that A corresponds with B. For example, I could test a belief about gravity by dropping something multiple times. If I see a pattern emerge, as we are pattern-detecting creatures, then I might be able to infer a rule.
This brings about 4 possibilities, being right (believing a truth, rejecting a falsehood) and being wrong (rejecting a truth, believing a falsehood). Certain beliefs are self-selecting, but as for the rest? Think about the ascent of man. Primitive tools getting gradually more complex. The domestication of animals and plants leading towards artificial selection. So beliefs themselves can be directly useful towards survival. Needing the right type of rock to make a hand axe or an arrow head, knowing the migratory paths of animals, selecting qualities directly seen on the animal. etc.
Again there's so much to explain and little space, so I'll finish with this. Beliefs themselves can be testable, and by having predictive beliefs and generally reliable sense data, there's the possibility to see whether a given belief can be true or not. Right now I'm sitting in front of a device that is built on the foundation of physics. Semiconductors made into logic gates, it's something that has come by measuring reality. Evidentially we have reliable enough beliefs to make computers, for how could the computer be even possible without having some ability to reason and measure reality? Evolution itself is not going to necessarily lead to all true beliefs, but with our evolved senses and reasoning abilities it would be absurd to think that the belief that electromagnetic force and magic smoke are equal explanations for how a computer works belies the process by which it was made.