I’m teaching undergraduate evolution this quarter, and right now am lecturing on natural selection. As always, I read the textbook along with the students, and this year’s textbook, as usual, is Evolution, by Douglas J. Futuyma. It’s a superb text, authoritative and well written. What struck me in this week’s reading were two statements. First this one:
[Darwin’s] alternative to intelligent design was design by the completely mindless process of natural selection, according to which organisms possessing variations that enhance survival or reproduction replace those less suitably endowed, which therefore survive or reproduce in lesser degree. This process cannot have a goal, any more than erosion has the goal of forming canyons, for the future cannot cause material events in the present. Thus the concepts of goals or purposes have no place in biology (or any other of the natural sciences), except in studies of human behavior. (p. 282)
(I do take issue with the characterization of goals and purposes as limited to humans: there’s plenty of evidence that some other primates—and perhaps some non-primate animals—have goal-directed and purposeful behavior.)
Here’s Futuyma’s second statement, referring to an experiment in bacteria:
This experiment conveys the essence of natural selection: it is a completely mindless process without forethought or goal. (p. 285)
And, indeed, this is what I teach—that natural selection, and evolution in general, are material processes, blind, mindless, and purposeless. (I also emphasize that—despite our shorthand characterization of selection as “acting” on individuals—it is not a “force” imposed on organisms from the outside, but simply a differential sorting of genes based on their contribution to reproduction.)
But when reading Futuyma’s statements, I remembered that some people object to such a description as a needlessly “theological” assertion: a flat and insupportable claim that natural selection was not designed by, and is not being guided by, gods. How can you be so sure, some theologians say, that there really isn’t a goal, purpose, or mind behind evolution?
You might remember that a while back the National Center for Science Education (NCSE) persuaded the National Association of Biology Teachers (NABT) to change its characterization of evolution, which originally read:
The diversity of life on earth is the result of evolution: an unsupervised, impersonal, unpredictable and natural process of temporal descent with genetic modification that is affected by natural selection, chance, historical contingencies and changing environments.
As NCSE Executive Director Eugenie Scott recounts, the words “unsupervised” and “impersonal” led to pushback from the faithful:
As one Christian said to me, defining evolution as “unsupervised” and “impersonal” implied to many Americans that “God had nothing to do with it and life has no meaning.” Reflecting these public concerns, two distinguished theologians, Cornell’s Huston Smith and Notre Dame’s Alvin Plantinga, wrote a polite letter to NABT’s board of directors, asking it to delete the two words “unsupervised” and “impersonal”. They specifically noted that the use of the two words has two unfortunate and unintended consequences. It gives aid and comfort to extremists in the religious right for whom it provides a legitimate target. And because of its logical vulnerability, it lowers Americans’ respect for scientists and their place in our culture.
Scott also considered such language to be a pollution of science with philosophical naturalism. And so she persuaded the NABT to drop the two offending words. (I’m baffled why they weren’t asked to strike out “natural” as well!)
In my classes, however, I still characterize evolution and selection as processes lacking mind, purpose, or supervision. Why? Because, as far as we can see, that’s the truth. Evolution and selection operate precisely as you’d expect them to if they were not designed by, or steered by, a deity—especially one who is omnipotent and benevolent. And, more important, the completely material nature of selection is of great historical and intellectual importance. After all, Darwin’s greatest achievement was the explanation of organismal “design” by a completely naturalistic process, replacing the mindful, purposeful, and god-directed theory that preceded it. That was a revolution in human thought, and students should know about it. (This achievement is also why Dawkins claimed, in The Blind Watchmaker, that “Darwin made it possible to be an intellectually fulfilled atheist.” Perhaps Darwin did not mandate that evolution ineluctably proves the absence of God, but he kicked out the last prop supporting the action of a deity in nature.)
Evolution and selection lack any sign of divine guidance. Earlier teleological theories based on divine or spiritual guidance, such as orthogenesis, have fallen by the wayside. Natural selection is a cruel and wasteful process. 99% of the species that ever lived went extinct without leaving descendants. There is no sign that evolution always goes in a fixed direction. Do primates always get bigger brains? There is some suggestion that orangutan populations evolved smaller ones. Fleas lost their wings; tapeworms lost nearly everything when evolving a parasitic lifestyle. There is no sign that the goal of evolution was Homo sapiens (if that were true, why the virtual extinction of Neandertals or the robust australopithecines)?
Now you can always say, along with many liberal theologians, that god just created the world, knowing that life would eventually arise and evolve largely by natural selection. If you add the caveat (viz. Kenneth Miller and Simon Conway Morris), that god made sure that evolution coughed up a complex and intelligent primate that would apprehend and worship him, then you have modern theistic evolution. But even liberal theologians have no explanation why God would use such a wasteful and tortuous process to produce humans. (Curiously, while they claim absolute knowledge that god used evolution to produce humans, these theologians bail when asked why he did it that way).
In the end, the absence of evidence for a godly hand in evolution is evidence of godly absence, for evolution and selection show precisely the characteristics they would have if they were purely material, mindless, and purposeless processes. There is no sign of orthogenesis, directed evolution, or a one-way march to Homo sapiens. There is no more evidence that god directed evolution than there is that god keeps the engine working in your car—and yet nobody keeps an open mind about the possibility that god is pushing their pistons.
To withhold from students the evidence that natural selection is purposeless—lacking direction, guidance, or goals—is to cheat them of the very essence of that process. It is part of the wonder and beauty of selection that this purely material process can produce species so exquisitely attuned to their environments. That is why Futuyma—and I—emphasize the undirected, material, and blind nature of selection and evolution.
I close with a quote from WEIT:
In the early 1800s, the French mathematician Laplace presented Napoleon with a copy of his great five-volume work on the solar system, the Mechanique Celeste. Aware that the books contained no mention of God, Napoleon taunted him, “Monsieur Laplace, they tell me you have written this large book on the system of the universe, and have never even mentioned its Creator.” Laplace answered, famously and brusquely: “Je n’avais pas besoin de cette hypothese-la,” “I have had no need of that hypothesis.” And scientists have not needed it since.