To see a fine thinker bamboozled by a minor fallacy is always a freaky spectacle, like watching an elephant trip over a peanut.  It’s sad, too: a little spring goes out of my step and my shoulders droop lower.  If the mighty can take such falls, what hope for the rest of us?  Consider G. K. Chesterton, who repeatedly proclaimed with ringing certainty that gradual evolution cannot produce a bat’s wing because a wing is useless until it’s complete—the old “you can’t fly with half a wing” argument.  (In fact, any fraction of a winglike structure might do an organism oodles of good, as the next flying squirrel you meet will attest.  Also, structures evolved for one function may turn out to be handy for another.)  Another example is Marilynne Robinson, the Pulitzer-winning novelist whose essays in The Death of Adam I have recently had the pleasure to encounter.

Robinson is one of those authors who give me the lovely feeling, while reading, of being better-educated than I really am.  She is a figure-skater of the mind.  Her essay “Darwinism,” in The Death of Adam, is a ripping good read.  Her discourse on the worldview implied by Genesis is eye-opening and beautifully written, and I cheer for her loathing for the dogma that a world of universal competition is the best possible.  But a cat may look at a queen, and I see a problem.

Robinson distinguishes between

evolution, the change that occurs in organisms over time, and Darwinism, the interpretation of this phenomenon which claims to refute religion and to imply a personal and social ethic which is, not coincidentally, antithetical to the assumptions imposed and authorized by Judaeo-Christianity.  (pp. 30-31)

This is promising, yet she goes on to thoroughly blur “Darwinism” as ideology with “evolution” proper.  In her next paragraph she speaks of “this theory called Darwinism,” pointing explicitly at the theory published by Darwin in The Origin of Species, 1859.  Yet Darwin did not claim to “refute religion” and the Origin contains no claim that evolution entails a particular “personal and social ethic.”  She then identifies natural selection as a “tautology,” by which is meant a circular statement (like “my mother is a woman”) that conveys no real information:

The popular shorthand version of it is “the survival of the fittest.”  . . . There is an apparent tautology in the phrase.  Since Darwinian . . . fitness is proved by survival, one could as well call the principle at work “the survival of survivors.”  This is not, strictly speaking, tautological, if the point is to bless things as they are, insofar as they are a matter of life and death. (p. 31)

The way in which Robinson suggests that natural selection is an “apparent” tautology is ambiguous at first blush, since “apparent” can mean either (1) obvious or (2) seeming real or true, but not necessarily so.  So is Robinson saying that natural selection is obviously tautological or only seemingly so?  The former, alas.  She states the idea’s alleged circularity in unequivocal language and then excuses it from strict tautology only on the ironical ground that it might have a normative or values-stating function, “blessing” life that manages to prevail in terms of mere survival.  [In her following paragraph, she elaborates on her view that natural selection is tautological.  A commenter charges me with unfairly representing Robinson on this point: that comment, and my reply to it, with Robinson quoted in full, can be seen below.]

The claim that natural selection is tautological, an empty elaboration of the trivial truth that survivors survive, is often made by creationists and periodically rediscovered by nonscientist intellectuals like Tom Bethell, [1] [2]  Karl Popper, [3] and Robinson herself.  It seems like a classic “Aha!”:  Who survives?  The fit.  Who are the fit?  Those who survive.  A mere circle of words!  

It’s not clear to me whether Robinson realizes what is at stake here; whether she knows that she is alleging that the whole of modern biology has been organized for 150 years around a painfully obvious brain-fart.  For according to biology, natural selection is the sifting mechanism that has produced not only the bat’s wing but your eyes, my brain, the fish’s tail.  As the Orthodox Christian evolutionary pioneer Theodosius Dobzhansky said, nothing in biology makes sense without evolution — and, we might add, nothing in evolution makes sense without natural selection.  For natural selection is what produces adaptation, wondrous structure.

Robinson’s assertion that natural selection is tautological is, therefore, intentionally or not, an attack on the core explanatory idea of an entire field of modern science.  If the attack is valid, then well and good (for the attack).  If not, then not so well, and not so good.

To begin with, spinning circular phrases out of an idea does not prove that the idea itself is circular: it is in fact an easy trick, and one could play it all day long.  Who, in general, wins the playoffs?  The best teams.  Who are the best teams?  Those that win.  So, then, do playoffs reveal nothing?  Are sports tautological?  No, because “winning” in sports, like “fitness” in biology, has specific physical meaning.  In any game, something real and particular happens on the field.  The winners must accomplish something not entirely random, namely the scoring of points against vigorous opposition.  Likely winners and losers can often be pointed out before a game based on observable, relevant differences.  The same is true of individual organisms’ evolutionary success (production of relatively abundant offspring).  Organisms must do real-world things: they must survive to reproductive age, resist disease, evade predators, obtain food, find mates, and so forth, all in particular real-world environments.  As Stephen Jay Gould puts it, fitness is expressed by differential survival, not defined by it.  [4]

What’s more, the principle of natural selection yields testable, nontrivial predictions, which no tautology could do.  When a dry spell in the Galapagos produces a shortage of small, easy-to-crack seeds, the principle of natural selection predicts that finches with larger beaks, which are better suited to cracking large seeds—finches that are, in these circumstances, “fitter”—will prosper relatively, and that inherited beak size will therefore increase in the next generation of birds.  This has been confirmed by meticulous measurements of beaks in the field (the famous Grant studies). [5]  The development of antibiotic and pesticide resistances also exemplifies the non-circularity of natural selection.  Scores of studies measuring selection in non-tautological action could be adduced.

So there is nothing fishy, counter-intuitive, or tautological about natural selection, the “survival of the fittest,” at all.  The sensation of insight that suffuses people when they discover selection’s circularity is a delusion.


Natural selection is not a tautology: its operation has been traced in nature, beak by beak and bird by bird, shaping finches in response to changes in food supply.  This image of four Galapagos finch species is from Darwin’s Voyage of the Beagle, 1845 edition.

Robinson rightly scorns bogus “survival of the fittest” reasoning by Darwin and others that justifies or softens the brutal behaviors of nations and classes.  I wince at her revelation that a 1980 writer used the extermination of native Tasmanians by rifle-wielding Europeans to illustrate the logic of natural selection.  But the ease with which the concept of natural selection can be hijacked does not tell us anything about its merit.  (The idea of God is easy to hijack too, but Robinson does not therefore reject it.)  She even claims, amazingly, that scientists have admitted that natural selection cannot be observed.  This, however, is false: scads of papers have been devoted to measuring the effects of selection, both in the laboratory and the wild.  Observing selection in action is one of the jolliest pastimes of working evolutionary biologists.

How does the elephant trip over the peanut?  How does Robinson get it so wrong?  Here’s my idea:

Ideas are sticky.  They clump, herd, associate.  Yet not all the associations that result are valid or meaningful: bad ideas may stick to good ones. When this happens, we may react to the resulting cluster as a whole, allowing our dislike of a prominent, smelly, bad idea to bias our treatment of a fine idea onto which it has glommed.  I speculate that some keen thinkers, like Chesterton and Robinson, screw up on natural selection because they first notice that some idea that natural selection happened to walk into the bar with, like eugenics or free-market absolutism, is evil hogwash.  They then find reasons to reject natural selection and so discredit the ugly doctrine that claims evolution as its authority.  This is natural, tempting, and intellectually disastrous.  And when Christians do it, we mirror the guilt-by-association thinking that some zealous antireligious thinkers practice.

Robinson is a truly important and worthwhile writer, and it will please me deeply if she someday renounces her fallacious claim that natural selection is tautological.  In the meantime, we all do well to remember that babies really are sometimes found in bathwater.








[5]  The data are here: