Alvin Plantinga is a professor emeritus from Notre Dame. Given that he is a philosopher, you’d expect better arguments than these three that he used in a New York Times interview.

You’d expect wrong.

I wondered if these were casual arguments, tossed out without much thought during a live interview. Could that explain why they were so poor? Nope: the original article makes clear that this interview was done by email, so Plantinga’s answers were presumably carefully considered.

Let’s move on to the final argument that I will be critiquing (part 1 here). (And there are more. Read the original interview if you want more weeds to chop down.)

#3. Evolution gives us beliefs that are just as likely to be false as true

The interviewer said, “So your claim is that if materialism is true, evolution doesn’t lead to most of our beliefs being true.”

Plantinga replied:

Right. In fact, given materialism and evolution, it follows that our belief-producing faculties are not reliable. Here’s why. If a belief is as likely to be false as to be true, we’d have to say the probability that any particular belief is true is about 50 percent.

Huh? Why imagine that beliefs are as likely to be false as true? We’ve seen this odd thinking before in his Evolutionary Argument Against Naturalism (I respond to that argument here). He begins with the valid observation that beliefs honed by evolution are useful for survival but don’t need to be true. (I’d argue that supernatural beliefs are an example.) His illustration is an imaginary Neolithic man who believes two odd things: that tigers are cuddly and that the best way to pet a tiger is to run away from it. The first belief is bad for survival and the second is false, but these two beliefs combine into a protective pair.

But why imagine it ends there? If every belief is a roll of the dice, our primitive man would have no beliefs shaped by reality. He might respond to sleepiness by drinking water, to thirst by finding a warm place, to cold by getting out of the sun, and so on. He’s too dumb to live, and that’s where evolution comes in. Reality is a demanding mistress, and beliefs not in accord with reality are judged harshly. If your beliefs for finding food, water, and shelter don’t fit well with reality, evolution will have something to say about it.

Plantinga clearly has little difficulty sifting true survival beliefs from false ones, and he’ll agree that we are all pretty good at this, too. And yet his hypothetical primitive man isn’t. I assume Plantinga concludes, via reductio ad absurdum, that such a man couldn’t exist, so therefore God must step in to impose correct beliefs on us. If evolution can’t be trusted to work for human beliefs, the same must be true for other animals, so God must impose survival beliefs on them, too.

I think I’ll go with the consensus view of the people who understand the evidence, not non-biologist Alvin Plantinga.

Extrapolate to many beliefs

There’s one more bit of childish logic that needs to be addressed.

Now suppose we had a total of 100 independent beliefs (of course, we have many more). Remember that the probability that all of a group of beliefs are true is the multiplication of all their individual probabilities. Even if we set a fairly low bar for reliability—say, that at least two-thirds (67 percent) of our beliefs are true—our overall reliability, given materialism and evolution, is exceedingly low: something like .0004. So if you accept both materialism and evolution, you have good reason to believe that your belief-producing faculties are not reliable.

First, our beliefs aren’t independent. When one belief has proven itself to be reliable through repeated use, we might build on that foundation by trying out additional provisional beliefs.

Second, it’s true that the more imperfect beliefs you collect, the likelier that one or more are false. Plantinga’s probability of 0.0004 for 67 out of 100 beliefs to be true may be correct when these tenuous beliefs have only a probability of 0.5 of being true. Survival beliefs, whether instinctive (“things that smell bad can make you sick if you eat them”) or taught (“prey animals tend to congregate at water holes at dawn and dusk”), usually have a probability of being true far higher than 0.5.

And finally, Christians and atheists all agree that human brains are imperfect. They can be changed by an injury, drugs, or a tumor. They’re subject to mental illness, dementia, biases, and illusions. They work less well when we’re hungry, stressed, or tired. (The story of Phineas Gage is a dramatic illustration that the mind is a product of a physical brain and nothing more.)

Plantinga is correct that our brains are imperfect, but then he proposes that Christians believe them when they report that God exists? The Christian claims are about the most ludicrous possible, and they need a mountain of evidence. Plantinga doesn’t have it.

Instead of faith, science compensates for our imperfect hardware with the scientific method. Conclusions are always tentative. There are rewards for overturning the consensus view. The result is science’s imperfect but still prodigious track record of results. Religion has, not a poorer track record, but no track record of teaching us new things about reality.

These three arguments add to the pile of really poor apologetics from famous Christians. I hope they provided a little practice for you and that you’re now better prepared in case you come across them in the future.

Perhaps the most optimistic spin I can put on this exercise is Catherine Aird’s observation, “If you can’t be a good example, then you’ll just have to be a horrible warning.”

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Image public domain
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Alvin Plantinga is an eminence within the Christian apologetic community, but even he can only play the hand he was dealt. He was interviewed by the New York Times and gave three arguments (or sub-arguments) so stupid that a high school student shouldn’t be allowed to get away with them (part 1 here).

One Christian responded to comments to the interview:

It appears that many of the commenters either didn’t read the interview carefully or didn’t understand Plantinga’s arguments. They’re much more sophisticated and formidable than some of the superficial dismissals of the commenters might lead one to believe.

Sophisticated and formidable? That certainly doesn’t apply to these arguments. See what you think.

#2. Moon no longer connected to lunacy

Plantinga’s interviewer asked about the God-of-the-gaps problem: explanation is a zero-sum game, and things that science explains well—like lightning, drought, and disease—no longer need the God hypothesis. The list of things that God could plausibly cause continues to shrink. The interviewer gave evolution as an example of something that science now explains much better than Christianity ever could and asked, “Isn’t a major support for atheism the very fact that we no longer need God to explain the world?”

Plantinga responded:

As a justification of atheism, this is pretty lame. We no longer need the moon to explain or account for lunacy; it hardly follows that belief in the nonexistence of the moon (a-moonism?) is justified. A-moonism on this ground would be sensible only if the sole ground for belief in the existence of the moon was its explanatory power with respect to lunacy.

Right—we have lots of reasons to believe the moon exists. Drop “Of course the moon exists—how else would you explain lunacy?” and you have more reasons. By contrast, we have pretty much zero reasons to believe God exists, and Plantinga in this article does nothing to change that.

The same thing goes with belief in God: Atheism on this sort of basis would be justified only if the explanatory power of theism were the only reason for belief in God. And even then, agnosticism would be the justified attitude, not atheism.

As we saw in part 1, Plantinga’s definition of an atheist is someone who says, “I’m certain God doesn’t exist” rather than “I have no God belief, but I’m not certain.” I agree that evolution’s explanatory power doesn’t prove that God doesn’t exist (and so can’t help atheist #1), but then that’s not my definition. I go where the evidence points (atheist #2), and by explaining the diversity of life on earth by evolution, “Darwin made it possible to be an intellectually fulfilled atheist” (Richard Dawkins).

Here’s my distillation of Plantinga’s argument: we have many reasons to believe the moon exists, so if one reason goes away, we’re still justified in believing in the moon. No one questions the existence of the moon, in no small measure because can all see it! Contrast that with God: before modern science, Christians explained puzzles in nature with the stock answer, “God did it.” There was no evidence to support this claim, but (in Europe) Christianity was pretty much the only game in town. Now with science explaining things far better than Christianity ever could, Christians have even fewer reasons to accept the Christian claims.

Plantinga tries to salvage his discouraging situation by acknowledging that there are fewer reasons to believe in God now but pointing out that the number of reasons isn’t yet zero.

Let’s return to the opening point, “as a justification of atheism, [God being replaced by science] is pretty lame.” Redefine atheism as most of us see it (lack of god belief), and science’s incredible track record for explaining reality vs. Christianity’s inability to teach us anything new actually makes a powerful argument. Not only does the Bible not pass on any useful science (how about a recipe for soap or an explanation of how to avoid spreading disease?), but many of its claims about nature are wrong.

Imagine someone saying that just because some of the miraculous claims for alchemy are false, that doesn’t make them all false. That’s true, but we now know that they are indeed all false. Christianity has traveled the same road.

Concluded in part 3 with the claim that beliefs provided by evolution are as likely false as true.

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Image from Marc Arias, CC license
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What better way to respond to atheists but to turn one of their own tools against them? That’s the approach philosopher Alvin Plantinga tries to use with his Evolutionary Argument Against Naturalism (EAAN). It’s not a new idea, and both C.S. Lewis and Charles Darwin anticipated it.
In brief, the question is: how can a human mind that’s the result of the clumsy process of evolution be trusted?
About “Darwin’s doubt,” Plantinga argues that only Christians can have confidence that their interpretation of the world is correct. Naturalists can’t prove that minds are reliable until they’ve proven that the source of this claim (the mind!) is worth listening to.
Here’s where Plantinga claims to have turned the tables:

The high priests of evolutionary naturalism loudly proclaim that Christian and even theistic belief is bankrupt and foolish. The fact, however, is that the shoe is on the other foot. It is evolutionary naturalism, not Christian belief, that can’t rationally be accepted.

He says that if evolution is true, human beliefs have been selected for survival value, not truth, so why trust them? And yet our beliefs are reliable, suggesting to Plantinga that something besides evolution created them.
Before we get into the specifics of Plantinga’s argument, let’s first establish a baseline. Plantinga and naturalists agree that humans’ needs and desires are pretty logically matched:

Feelings or desires are on the left, actions are on the right, and the arrow is the belief that a particular action will satisfy that desire.
This is straightforward. A human with the feeling of hunger has the belief that eating food is the action to take. You go toward cuddly things, you run from scary things, you get to clean air if you can’t breathe, and so on. This is the world we all know and understand.
But Plantinga says that naturalists delude themselves. He imagines the naturalist’s world in which these links are jumbled. He imagines a hominid Paul who has some problematic beliefs about predators:

Perhaps [Paul] thinks the tiger is a large, friendly, cuddly pussycat and wants to pet it; but he also believes that the best way to pet it is to run away from it.

So Paul’s instincts toward tigers keep him alive, but only by dumb luck. But unreasonable beliefs don’t stop with tigers. Plantinga imagines the naturalist’s view of the world with beliefs having no connection with reality. That is, he imagines something like this:

Paul’s response to the tiger was just a roll of the dice, and he got lucky. But Plantinga supposes that all of Paul’s beliefs are arbitrary, not just those about tigers. Some actions in this chart are benign, but some are dangerous. When Paul sees something scary, his reaction is to walk toward it. When he’s drowning, he’ll try to sleep. When he’s hungry, he’ll satisfy that need with fresh air, and so on. With his basic desires paired with ineffective methods, this guy is clearly too stupid to live.
This is where natural selection comes in. Natural selection is unforgiving, and belief sets that don’t lead to survival are discarded. Evolution easily explains why Plantinga’s Paul didn’t exist.
An article at Skeptic.com neatly skewers Plantinga’s argument with a familiar example.

If a professional baseball player [incorrectly perceived reality,] that is, if his perception of the movement and location of a baseball was something other than what it actually is, then he would not be able to consistently hit ninety-five mile per hour fastballs.

As an aside, let me admit that I have a hard time maintaining respect for those at the leading edge of philosophy. Do they do work that’s relevant and pushes the frontier of human knowledge? I’d like to think so, but when this is the kind of argument they give, it’s hard to keep the faith.
My advice to philosophers: when you get the urge to play scientist, it’s best to lie down until the feeling goes away.

If we’re made in God’s image,
then why aren’t we invisible, too?
— graffiti

Photo credit: Wikimedia