The Argument from Misunderstanding How Natural Selection Works

The Argument from Misunderstanding How Natural Selection Works February 4, 2016

skepticalmonkey_thumbIn my last post, I examined four (bad) arguments for the existence of God presented by Tim Keller in Chapter 8 of The Reason for God. I call them the Argument from Inexplicability, the Argument from Fabricated Probabilities, the Argument from Wishing, and the Argument from Regularity. As I’ve often pointed out, not only are arguments like these untenably weak, but even if they weren’t, they would still fail to establish which kind of God they are supposed to be supporting.

See, even if we were to concede that the universe had to have a supernatural cause, that concession still wouldn’t take us the remaining 32 logical steps it would take to get from “something supernatural” to “a singular, personal, benevolent, masculine, transcendent-but-sometimes-incarnational paternal being who communicates intelligibly via one-and-only-one-specific ancient religious text, which is infallible in its original manuscripts, to be correctly interpreted only by those who hold to trinitarian Christian theism and who are also themselves male.”  I know, right? It’s a bit much. But I swear to you that all of those things are non-negotiables for pretty much anybody using the method Keller uses. They just play a few of those details a bit closer to the chest.

Keller gives one more argument at the end of Chapter 8 which I will call “The Argument from Misunderstanding How Natural Selection Works.” He seems to feel this is a “gotcha” for atheists, exposing what he understands to be a weakness of both philosophical naturalism and the theory of evolution itself. He conflates those two things in a way which betrays his own deep distrust of the science behind evolutionary theory. More often than not in this book, the term “evolutionary theorists” signifies his antagonists, which is noteworthy coming from a man who just a few pages earlier tried to argue that his religious tradition does not pit faith against science.

For the record I think God guided some kind of process of natural selection, and yet I reject the concept of evolution as All-encompassing Theory. (p.98)

I remember how odd that sentence struck me when I first read it. It sounded like a disingenuous accommodation, a superficial concession made toward a complicated and comprehensive system of ideas which I’m not so sure Keller really understands. Now that I’ve read how he uses the term “natural selection,” I am even more convinced that he really doesn’t understand what that phrase means. After I explain what he doesn’t seem to grasp, I’m going to elucidate why his “gotcha” really isn’t a gotcha at all.

Misunderstanding Evolution

First of all, Keller oversimplifies the mechanisms of evolution in such a way as to misrepresent which forces are at work in nature:

…the school of evolutionary biology…claims everything about us can be explained as a function of natural selection. (p.140)

That’s not exactly correct. Evolutionary biology does not claim that everything about us can be explained as a function of natural selection. That is only one of the forces at work in evolution, and Keller’s failure to mention the other—the one most responsible for our world’s amazing biodiversity—shows that his grasp of the science behind what he is critiquing could use some work.

People often speak of two interacting forces—one creative and the other destructive, in a sense—working together to produce what we call evolution: mutation and natural selection. Mutations occur mostly at random (although some happen as a direct response to the influence of an organism’s surrounding environment), and they produce the limitless biological diversity that has so richly populated our ecosystem from its earliest days. Those mutations which favorably adapt an organism and its offspring to the ever-changing environment tend to be preserved into the next generation because, at least eventually, those mutations which do not favorably adapt an organism to its environment don’t make it into subsequent generations, thus eliminating those traits over a long period of time (that detail is important).

That’s the part we call natural selection. We talk about nature “choosing” to reward one trait over another as if it were an intelligent force because after each disadvantageous trait is eliminated, this process will appear more and more purposeful in retrospect. But nature isn’t really “thinking” at all, nor is it a conscious entity which can “choose” or direct the development of the species according to any discernible design. That is why so many irrational and unhelpful biological traits will come and go before each new outgrowth of speciation is complete.

Why does this matter? It matters because whenever people conflate those two forces the way Keller does, the apparent purposefulness of natural selection tends to obscure the randomness of the process of mutation, leading people to think that evolution moves in a straight line. But it doesn’t. Evolution is a stochastic process (google it) in which living things can morph and develop into almost any imaginable direction, logical or otherwise. Not every trait which evolution produces is beneficial to the organism, nor does each one necessarily have to impact the ability of the organism to survive or reproduce. Only time will tell whether or not each development will provide a benefit to the organism.

Evolutionary biologists understand this, but it seems that Keller doesn’t. He seems to think evolutionary theory necessitates that each new biological development must be beneficial to the organism’s survival, leading him to demand things from evolution which it will never reliably provide, things which no one who really understands how evolution works would ever come to expect from it. For example, despite the usefulness of our highly evolved brains, there is nothing within the evolutionary pressures of nature which would ensure that the ideas and beliefs which they conjure up bear any necessary correspondence to reality. There is nothing which precludes our entertaining and accepting any number of irrational ideas, even crazy ones. Keller is convinced this constitutes an insurmountable philosophical problem for us.

Why Our Minds Don’t Have to Be Reliable

Keller argues that those of us who accept evolution should be scandalized by the fact that natural selection cannot guarantee that our minds accurately perceive everything about the world around us.

Evolution can only be trusted to give us cognitive faculties that help us live on, not to provide ones that give an accurate and true picture of the world around us. (p.141)

This is a huge Achilles’ heel in the whole enterprise of evolutionary biology and theory. (p.143)

As a side note, here again we see this subtle, underhanded disdain for science making its way into the text despite Keller’s contention that his faith does not militate against human reason. Like his hero C.S. Lewis before him, he wishes to argue that his faith is a reasonable faith, contrary to the apostle Paul’s refrain that spiritual realities operate on a different plane, so that appealing to human reasoning is futile (see 1 Corinthians 2). But unlike C.S. Lewis, Keller is a Calvinist and a presuppositionalist, which makes him highly tentative about accepting the conclusions of modern science.

Lewis comfortably maintained that the biblical Adam and Eve cannot be anything more than metaphors, but Keller’s theology will not allow such a perspective. Keller admits elsewhere that he believes Adam and Eve simply must be seen as a literal historical couple because the Bible says they were. Anything else is unacceptable. Despite his own attempts to present the Christian faith as compatible with modern science, he simply cannot stay the course, and eventually falls back on an anti-scientific position.

[Read “Sorry Apologetics: What’s Wrong with the Presuppositionalist Approach“]

Getting back to our main point, Keller argues that naturalistic evolution cannot possibly guarantee that anything we think corresponds to reality or truth. Taking his cue from Reformed darling Alvin Plantinga, he argues that naturalism is a self-defeating ideology because it cannot guarantee that minds produced by purely natural forces can accurately perceive truth.

If our cognitive faculties only tell us what we need to survive, not what is true, why trust them about anything at all? (p.142)

First of all, I cannot help but point out once again his error in thinking that evolution can only give us that which pertains to raw survival. That point isn’t essential to this line of argumentation, but it’s a recurring annoyance which bears repeated correction. Many of the things which our creative brains have helped us develop have little or nothing to do with survival—things like art, music, film, scientific exploration, philosophy, and Pinterest. We do so many things which make us happy but aren’t required for survival at all. But I digress…

It seems that evolutionary theorists have to do one of two things. They could backtrack and admit that we can trust what our minds tell us about things, including God…Or else they could go forward and admit that we can’t trust our minds about anything. (p.141-142)

Keller thinks it should be a problem for “evolutionary theorists” to discover that we cannot rely on our own minds to tell us what is true and what is not. Perhaps he thinks this is a problem because of the aforementioned misunderstanding about how natural selection works. To him and to Plantinga, this seems to be a logical defeater built into naturalism which invalidates it from within.

But who says we ever expected our minds to be infallible guides to truth? I’m sure there are people out there who go that far (Ayn Rand and other logical positivists come to mind), but there is nothing inherent within naturalism which necessitates jumping to that conclusion.

…it is ultimately irrational to accept evolutionary “naturalism,” the theory that everything in us is caused only by natural selection. If it were true, we couldn’t trust the methods by which we arrived at it or any scientific theory at all.  (p.143)

No, that’s not actually correct. Because you see, the scientific method contains within itself a process for sifting through the false beliefs we accumulate (including the ones we have about science itself) so that we don’t have to rely on the ability of our own minds to arrive at a true picture of the world around us. I’ve written about this before, but skeptics and Christians essentially agree with each other on this one point: We both agree that we cannot trust ourselves to grasp reality in a completely unbiased manner. Where we part ways is in choosing what will save us from the limitations of our own imperfect perceptions. For the skeptic, that savior is rigorously-tested, always-improving-upon-itself empirical observation (i.e. the scientific method), while for Keller it is, ultimately, the Bible.

[Read “What Will Save Us from Our Own Subjectivity?“]

We do not need our minds to be perfectly reliable in the way that Keller suggests. We should all be able to agree that our minds can help us successfully accomplish most things that we attempt. The evidence for that is all around us. Who didn’t marvel three years ago when we remotely landed a one-ton bucket of bolts and circuit boards on Mars that we launched nearly nine months earlier on a 350-million-mile trek across the solar system? Clearly our minds can accomplish a great deal, especially with the help of the intellectual tools we have developed, like math and science.

Keller knows these tools are effective, and I would argue that he trusts them to produce reliable results every single day of his life—right up until the moment one of them suggests there’s something wrong with his religious beliefs. Now suddenly science is a thing to hold at arm’s length.

But it is simply not true that either philosophical naturalism or evolutionary theory demands that we believe our minds are always reliable things. Again, that is why we invented science in the first place. We knew all too well how good we are at fooling ourselves.

The Achilles’ Heel of Keller’s Approach

Throughout this book, Keller’s approach to apologetics suffers from the same weakness that I see among all presuppositionalist apologists. Following the lead of Cornelius Van Til, who invented this approach, Keller spends the majority of his time engaging in an “internal critique” of those worldviews which he would like to discredit rather than demonstrating why his own should be chosen instead. In essence, the presuppositional method of apologetics always hinges on invalidating the other guy’s perspective without doing a great deal of work to establish the validity of its own:

Just because you have found what you believe are shortcomings in my philosophical framework doesn’t automatically means points for your own. You have to actually provide evidence that establishes how yours performs better at grasping the world the way it actually is. I have never seen this done, and I’m pretty sure at this point it is because it cannot be done. I’m always open to being proven wrong, mind you, but each new person who purports to do so resorts to the same predictable sleights of hand, which signals to me that I’m dealing with the same mind games I was taught to play throughout my own upbringing.

Keller thinks that if he can show philosophical inconsistencies in other people’s ways of thinking, that automatically means his own should gain our trust. But it’s not that simple. Somewhere along the way, he’s got to show us real reasons to believe this stuff. It simply won’t do to keep saying “You can’t explain how X happens, therefore my Giant Invisible Person hypothesis must be correct!” And it especially won’t do him or us any good if he first misunderstands how natural selection works, then turns that misunderstanding into a “gotcha” about how we rely on our own minds for finding truth.

The bottom line is that we don’t rely on our own minds at all. That’s why we invented the scientific method in the first place.

[Image Source: Imgur]


If you’d like to read the rest of my responses to Keller’s chapters up until this point, you can find them listed here:

(Other Posts in this Series)


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