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I saw on Twitter another version of the old you-can’t-trust-reason-without-God argument, under the title “On the futility of attempting rational discourse with atheists.” It went like this.
1. Anyone who accepts atheism accepts naturalism.
2. On naturalism, the reliability of human reason is astronomically improbable.
3. Therefore, anyone who accepts naturalism has a defeator for any conclusion whatever reached on the basis of reasoning, including the conclusions of naturalism and atheism.
4. Therefore, atheism can never be accepted by anyone on a rational basis, since every atheist eo ipso has a rational defeator for his own acceptance of atheism.
5. Therefore, all atheists accept atheism on wholly non-rational grounds.
6. Therefore, every atheists just as such places himself outside the sphere of rational discourse.
7. Therefore, it is pointless to attempt to engage an atheist qua atheist within the sphere of rational discourse.
I thought this smelled familiar (e.g. “defeator”), and indeed the person who posted the argument points us later to Alvin Plantinga’s Where the Conflict Really Lies: Science, Religion, and Naturalism (highly recommended, incidentally) in which this appears.
Before tackling premise #2 (#1 is obviously true), but assuming it’s force, what is amusing are the atheists’ response to the posting. One fellow wrote, “Both empiricism and rationalism have brought us this far, and have served us well. To deny this fact is just a delusional claim.” Another said, “While that’s fortunate for theists, we can test our faulty reasoning against reality. Unfortunately, under theism we can’t trust reality.”
Premise #2 asserts the fallibility, untrustworthiness, and groundlessness of human reasoning under the assumption of naturalism, therefore to answer, as these atheists implicitly do, that “I love muh rationality and muh naturalism” is no better than saying “Is not!” to the argument’s “Is so!”
As we all know by now, all probability is conditional, and premise #2 speaks of probability. What are the conditions the argument has in mind that makes the reliability of human reason “astronomically improbable”?
Naturalism is, of course, the philosophy that supernaturalism is false; a theorem of naturalism is that all that exists is matter and energy and various forces between them, i.e. the material world. That’s one condition, and a restatement of premise #1.
We’re here and arguing and thus using some form of intellectual apparatus, so, accepting naturalism, we had to get here somehow and develop this apparatus. Call that somehow evolution, or whatever you like, as long as you don’t appeal to God and immaterial intellects and so on.
Now what guarantee is there that the mechanism that brought us to this point aligns our intellectual facilities with the truth?
None whatsoever. It is common to declare that evolution, operating in whatever mechanism you have in mind, caused our brains to produce ideas and convictions aligned with that which enhances our procreative abilities. Yet there no proof these ideas and convictions must be what is true. You can argue that they must be, but then you are arguing in circles, assuming what you wish to prove. Because it is logically possible that evolution caused us to believe what is false (at some times or even most times) or to reason badly. All we can say for sure is that we’re here. There is no proof on any conjecture beyond that.
After all, dear atheist, it is true, is it not?, that the vast, vast majority of those who have ever lived have accepted supernaturalism and have managed to reproduce just fine. Yes? Given the relative performance of baby making, the religious have been and are still superior — on average, of course. Thus, rationality, if it be true, appears deleterious, especially when rationality causes some kind of socialism (this is only a mild joke).
You may say you have designed an experiment to test whether our intellects are aligned with the truth, but this experiment, however it is constructed, must assume what it seeks to prove. At the least, we have to assume our intellects can map from experiments to truth, and there is no proof of that. It is only an assumption. It could be — it is logically possible — we have a built-in observational bias which causes us to misinterpret from only a few things to everything we see.
Of course, all of this is absurd; our intellects work just fine. Mathematics is in no danger, neither is philosophical argumentation like this. But that is because there is an Ultimate Grounding and reason for us to trust our rationality.