Yesterday's post introduced neuroscientist Linda Barrett and her book Seven and a Half Lessons about the Brain. I wrote yesterday that much of what she says in her short volume raises interesting philosophical questions. Here's another example:
Her book has a chapter in which she notes that the brain does not give us a photograph of the world, rather it constructs an image that may or may not correspond to the way the world actually is or may only partly correspond to the way the world is. She writes, "Our brains aren't wired for accuracy, they're wired to keep us alive."
This has interesting implications. It's another way of saying that our brains can't be trusted to always lead us to the truth of things because that's not their primary job. Their job is to manage all the sundry systems of the body and to keep them functioning.
Barrett gives a fascinating illustration of how the brain, by prioritizing survival over accurately representing the world, can deceive us.
In the 1970s before Rhodesia became Zimbabwe, a young man was drafted into the Rhodesian army and told to hunt down guerilla fighters. He was actually sympathetic to the guerillas, but he did as he was ordered. One morning while deep in the forest with a squad of soldiers he detected movement up ahead.
Stealthily moving forward, he saw a line of guerilla fighters dressed in camouflage and carrying automatic rifles. He raised his rifle, flipped off the safety switch, and took aim at the leader of the group who was carrying an AK-47. Suddenly he felt a hand on his shoulder. "Don't shoot" whispered a squad mate behind him. "It's just a boy."
He lowered his rifle and looked again at the line of guerillas. They weren't guerillas. They weren't even men. They were a line of cattle being led done a forest path by a boy of about ten years of age with a staff in his hand.
The soldier for years afterward was perplexed by this unsettling experience. How could he have been so mistaken about what he saw? Did his brain, under the enormous stress of the moment, deceive him?
Less dramatic examples of similar phenomena have probably happened to most of us. We were convinced we were seeing one thing, but on closer inspection it turned out to be something else.
Now here's the problem this raises. If we are naturalists who believe naturalism is true and that evolution has produced a brain that isn't wired to lead us to truth, especially truth about metaphysical matters which cannot even enlist support from the physical senses, how can we confidently claim that naturalism is true? Or evolution?
We can only have warrant for trusting our brains - our reason - to lead us, most of the time, to truth about the world if our brains were in fact designed by an intelligent Mind who engineered them to be fairly reliable guides to truth. If we are naturalists who deny the existence of such a Mind we have no sound basis for believing naturalism is true or for believing that such a Mind doesn't exist.
In other words, the only way we could be confident that naturalism is true is if it is false. If we are naturalists we must acknowledge that our belief in naturalism is a blind leap of faith.
One thing more: What Barrett writes about has implications for our judgment of police behavior. Occasionally officers will shoot a suspect they claim to have threatened them with a weapon only to discover after the fact that there was no weapon. Perhaps we assume the officer was lying, but this might be an unfair and hasty judgment.
Perhaps, as in the case of that Rhodesian soldier, stress really does cause people to see things that aren't there, especially things like a weapon that the brain determines could well be there.
In fact, Barrett says that it's perfectly normal to see a grown guerilla with a rifle when you're looking at a mere boy with a stick. The brain's job is to keep you alive and so, based on memory and training, etc. it sees what it expects to see and produces a behavior that it calculates to be necessary to keep you alive.
Maybe something similar is at work in the brains of police officers who are under enormous stress and must react in fractions of a second to potential threats. Perhaps in at least some of these cases the officer's brain really did cause him to see a weapon when none was found.