The Argument from Reason

Why the atheist/naturalist can't trust his brain

If naturalism (materialism) is true, then your thoughts are just chemical reactions in your brain, determined by the laws of physics. But if your thoughts are just fizzing chemicals, why should you trust them to tell you the truth?

If there is no God and everything is material, then the human brain is essentially a biological machine, Your thoughts are not produced by "reason" or "logic"; they are produced by neurons firing

The only thing driving the development of the brain was Evolution. But that is where the problem starts. Evolution does not care about what is true; it only cares about what helps you survive.

If a caveman hears a rustle in the grass, it helps him survive to believe "It's a tiger!" and run away. It doesn't matter if it was actually just the wind. [Plantinga's example]

Thus, If our brains were built strictly for survival (per evolution) then we have no reason to trust them when they try to do complex things that don't help us survive, like quantum physics, philosophy, or arguing about the existence of God.

This is the fatal flaw in the atheist worldview. An atheist uses their brain to reason, "There is no God; everything is just random atoms."

But if that statement is true, then the brain they used to come to that conclusion is also just random atoms. It wasn't built for truth; it was built to hunt, reproduce, survive.

It’s like shaking a box of Scrabble letters and having them accidentally spell out a sentence. The sentence might exist, but you wouldn't trust it to contain deep meaning because it was created by random shaking, not an intelligent mind.

To trust our own brain, our own logic, we have to believe that our reasoning power comes from a rational source.

If God exists (a Rational Mind), then He created our minds in His image, specifically so we could understand the universe.

The atheist, naturalist, critic cannot use reason to disprove God, because the validity of reason depends on God. As C.S. Lewis famously put it: "Unless I believe in God, I cannot believe in thought: so I can never use thought to disbelieve in God."

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A common counterargument to this is to point to evolution. Evolution, the defender of "natural logic" will say, favors humans who can correctly reason over those they cannot. 

Therefore, there is a reason to think mindless forces produced reliable reason in us!

But they forget that in a naturalistic worldview, everything is the result of matter acting in accordance with the physical laws. Not the laws of logic. So, when the atheist cites "reason" or a "reasonable conclusion", it really just the result of an unintelligent, mindless, material process that follows the physical laws, not logic/reason. 

But what of the Theist? She is not bound by the natural or by the physical laws. Thus, that which constrains the atheist/naturalist brain does not do so to the Theist. The Theist is free from the bounds of the physical and can engage in critical thinking as governed by the laws of logic. 

Is the Argument from Reason is Too Successful For its Own Good?