More Than the Sum of Our Senses

More Than the Sum of Our Senses November 4, 2013

I’m still reading Timothy Keller’s book. He’s very much a fan of presuppositional apologetics, like this one in which he argues that an intelligent being that came about through evolution wouldn’t be able to trust its own reasoning abilities:

Evolutionists say that if God makes sense to us, it is not because he is really there, it’s only because that belief helped us survive and so we are hardwired for it. However, if we can’t trust our belief-forming faculties to tell us the truth about God, why should we trust them to tell us the truth about anything, including evolutionary science? [p.143]

I tackled this argument in one of my first posts on Daylight Atheism, Are Evolved Minds Reliable Truth-Finders?, but now’s a good time to say some more about it.

In that earlier post, I argued that we can know presuppositional arguments like this one are wrong because we’re evolved beings. If we were created beings – say, an android built and programmed by an engineer – then we’d have no way to be sure our minds were generally reliable. If our creator was malicious or whimsical, then they could have implanted any behavioral rules they pleased in us, even foolish or self-destructive ones. (You’ll note the parallel with the way, according to Christian theology, that God gives us powerful impulses to do things he doesn’t want us to do, then punishes us severely for following them.)

But human beings are a product of evolution, and evolution is neither malicious nor whimsical. It’s a blind, mechanistic process concerned only with results, namely the ability of living things to survive and reproduce. And, like all living things, the only way we can survive and reproduce is if we’re adapted to take the correct actions in the face of danger or opportunity.

Although simple creatures can be driven by pure instinct, like the Sphex wasp which follows a behavioral program that “resets” if disturbed at any step, that would never work for social creatures like us. Unlike other species which have only a limited repertoire of behaviors, we’re much too behaviorally complex to be programmed with hardcoded rules for every situation we might face. Therefore, the only option open to natural selection would be to shape us into general-purpose reasoning machines that can draw correct inferences in many different circumstances and act on them accordingly.

That’s not to say we never get things wrong. Keller advances a false-dilemma fallacy in which our evolved truth-detectors are either completely trustworthy (and therefore God must exist because people believe in him) or completely untrustworthy (and therefore we can’t know anything, including whether we evolved). Obviously, the reality is in between.

We know our evolved truth-detectors are generally reliable, but we also know that they can be fooled. Our individual senses and cognitive circuits evolved to exploit predictable regularities in the environment – assumptions about the direction of light, the contrast of colors, the way moving objects follow the same course even when we can’t see them, the way complex phenomena are usually caused by other agents, and so on – and like the Sphex wasp, they can be tricked by situations that subvert these built-in assumptions.

But here’s what Keller misses: to evolve a truth-sensitive intelligent being, you don’t need one infallible truth-detecting sense or unsubvertable reasoning capability. What you need is a being with many different senses that are fallible in different ways. If you encounter a situation that deceives one of your senses, the other ones can weigh in, showing you how you were led astray so you don’t make the same mistake twice. This is well within the capabilities of evolution, and it’s always how you build something that’s greater than the sum of its parts. And since we can learn from others, we don’t have to make every mistake ourselves to learn from them; we can be as smart as the combined intelligence of all those who preceded us.

It’s when you don’t follow this process of self-correction that you’re led into error. Needless to say, this is a lesson that religion like Keller’s – which is more or less a concerted effort to preserve beliefs in the face of contradictory reason or sense data – ought to be worried about.

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