22 October 2009

Why Evolution Matters (Part 2 of 3)


Probably the most heated battle ground in the culture war between secular science and organized religion is the debate surrounding evolution. Why do science-minded people take this theory so seriously? Why are there well-funded organizations (such as the American Association for the Advancement of Science) armed with lawyers, scientists, and educators bent on countering the efforts of creationists and proponents of intelligent design? The simplest answer was penned by Theodosius Dobzhansky in The American Biology Teacher, (1973): “Nothing in biology makes sense except in the light of evolution.” As I have explained in more detail elsewhere, the theory of evolution by natural selection is central to biology. A scientific theory proposes a grand explanation for the way things are and offers hypotheses, which are testable predictions for what we should see if the theory is correct. If the explanation is not testable, it’s not scientific. The theory of evolution is the scientific community’s best effort to explain why there are so many forms of life on earth, why all life is remarkably adapted to its environment, and why different organisms have so much in common.

Let me make a careful distinction here: the term “evolution” simply means “change over time”, whereas “evolution by natural selection” or “Darwinian evolution” is the prevailing theory explaining how evolution occurred. Long before Darwin published On the Origin of Species, it seemed to many naturalists that the relationship between living things looked an awful lot like a big family tree. If you start with, say, your pet cat, it’s clearly a different species than a tiger, but similar enough that you could imagine they have a common ancestor. Stepping back a level from cats, they aren’t really all that different from other 4-legged mammals; they have similar skeletons, the same number of toes, the same internal organs, etc. Now consider all mammals to be one branch of the family tree, with other branches for the reptiles, the birds, the fish, the insects, etc. These branches would all be on a different part of the family tree than the branches for plants and fungi. At the very root of the tree we would find single-celled organisms such as bacteria and yeast, tiny little living things that use the same DNA and amino acids and proteins as all their myriad multi-cellular cousins. At first glance your cat doesn’t seem that similar to cockroach, but viewed in light of the whole of life on Earth, they appear to be cousins in a really big family. The question that scientists ask is WHY? Why does life appear this way? This is what the theory of evolution by natural selection attempts to explain, and it explains life on Earth so well that it is considered by most scientists to be not only the best, but the only explanation. Without the theory of evolution by natural selection, biology has no explanations. Without explanations, scientists get very cranky, because explaining things is what we do. This is why scientists take evolution so seriously.

I am well aware of the objections, even scientific objections, to evolution by natural selection. There are enough people on all sides battling it out elsewhere, so let’s not get into it here. What I want to explore with this post is motivation. I have just explained why scientists take evolution so seriously. You might just as well tell me to explain chemical reactions without orbital theory as ask a biologist to explain life without evolution. But why is evolution important outside of the biology lab? In my last post I explained why Christians think the creation-evolution debate is so important. But what about non-religious folk, so-called secularists? What about atheists? Several of the most prominent leaders of the so-called “New Atheists” movement, such as Richard Dawkins, Jerry Coyne, and P.Z. Meyers, are not only pro-Darwin, they are biologists. Why has evolution by natural selection been a rallying point for the war against religion? I think the explanation is rather simple: the need for explanation.

A popular term among theologians these days is “narrative”. What is the story that you find yourself in? Where did you come from? Why do believe what you believe? In the absence of a faith tradition, the atheist adopts a different narrative. That narrative appears to be science. Science as a philosophical tool presupposes that everything we observe can be explained by natural causes obeying predictable, describable rules of the universe. Science assumes that God, miracles, and the supernatural (including unicorns, faeries, and the Flying Spaghetti Monster) do not exist, not because scientists are themselves non-religious, but because most of the time the world works in an orderly and predictable way without the apparent intervention of the supernatural, and science is a great way to discover the rules underlying the day-to-day functioning of our universe. Atheists have simply taken the next step and decided that science is the best and only way of knowing about everything that there is. The premise that everything we observe is explainable by natural, predictable, and describable causes is no longer a philosophical tool but a simple fact. And who can blame them? Science has been so successful at explaining so much that it’s hard to imagine a role for the supernatural. In a world where we do not see water turned into wine or messiahs raised from the dead, science can explain the origin of life, the behavior of societies, even the chemical basis for the emotions we feel when we have religious experiences. Science as a world-view provides a narrative for those who believe that what we see is what we get: there probably is no God, so stop worrying and get on with your life. Whether the practice of science leads to atheism or atheists have co-opted science as their preferred epistemology is immaterial; it is a fact that if you hang around scientists and science advocates, you’re going to find more folk that don’t believe in any sort of god than those who do, and, in my opinion, it’s not hard to see why.

The theologian Paul Tillich believed that atheists are an unlikely ally of the faithful because they destroy our petty idols. Any god that cannot withstand the scrutiny of the human intellect is no god worth worshipping. As a scientist, I have great respect for the power of the scientific method to explain almost everything we observe in the world. Still, I find science lacking as a narrative, and I believe that the atheist worldview misses out on the fundamental human experience of interacting with the ultimate. But more on that later.


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