This statement is not a tautology

In honor of MarkCC’s latest effort to explain to the deeply egnorant Michael Egnor why the fact that any inferentially true set of statements ? including scientific theories ? can be reformulated as a tautology, I thought I’d crack open Elliot Sober’s excellent Philosophy of Biology, in which he discusses the relevance of the “tautology” objection to evolution. But before doing that, I have to take exception to something Egnor said. I actually take exception to nearly everything he says, but I’d rather not bog down in the details. Egnor tries to summarize natural selection as “survivors survive,” but that is not at all the issue.

Just as Newton’s first law states that an object at motion tends to stay in motion (all else being equal), natural selection states that the offspring of survivors will tend to survive (all else being equal). This statement, on its own, is not any sort of tautology. Even “survival of the fittest,” is not tautological in the strict sense of the term.


Sober explains this point thusly:

Before I address the criticism, the term “tautology” needs to be clarified. The first important point is that propositions are the only things that are tautologies. Not all propositions are tautologies, but all tautologies are propositions. A proposition is what is expressed by a declarative sentence in some language; it is either true or false. But notice that the phrase “the survival of the fittest” is not a declarative sentence. If we are going to assess whether “the survival of the fittest” is a tautology, we first must be precise about which proposition we wish to examine.

After discussing the formal logical statements that are always tautological (P or not-P, etc.), Sober observes that people sometimes refer to a statement as tautology because of the meanings of the words in the sentence. “All bachelors are unmarried” does not have a logical structure that makes it tautological; “all x are y” is only true because we know something about x and y. Because we know that a bachelor is an unmarried man, we can understand that the statement must be true. Sentences which can be evaluated for truth or falsity based on definitions are called analytic, those which require other information are referred to as synthetic.

We have to reformulate “survival of the fittest” into a different form, then, to know if it is tautological. Egnor seems to think it translates to “all survivors survive,” which turns out to be neither accurate nor true. As the Boss says, “everything dies, baby that’s a fact.”

Sober reformulates it as “The traits found in contemporary populations are present because those populations were descended from ancestral populations in which those traits were the fittest of the variants available.” Egnor might want to summarize that statement as “survivors have traits which they pass on to future generations.” As Sober observes:

this statement is not a tautology; it is not a truth of logic that present populations were descended from ancestral populations. This implication of the statement is true enough, but it is no tautology. The second thing to notice is that the statement, taken as a whole, is false. A trait now at fixation in some population may have reached fixation for any number of reasons. Natural selection is one possible cause, but so are random genetic drift, mutation and migration.

Incidentally, it is a curiosity of some creationist argumentation that evolutionary theory is described as being (1) untestable, (2) empirically disconfirmed, and (3) a tautology. This nested confusion to one side, the main point here is that the statement displayed above is not a tautology and, in any case, is not part of the theory of evolution. Far from being an analytic truth, it is a synthetic falsehood.

As Sober goes on to point out, the theory of evolution may well contain some tautologies. For instance, defining fitness is complicated, and one can formulate definitions which would be tautological. He goes on to note that “the fact that the theory of evolution contains this tautology does not show that the whole theory is a tautology. Don’t confuse the part with the whole. Perhaps what is most preposterous about the “tautology problem” is that it has assumed that the status of the whole theory depends on the verdict one reaches about one little proposition.”

Later, Sober observes that physical laws tend to be empirical claims (eg, mass attracts mass) while evolutionary laws (like the Hardy-Weinberg equilibrium) “once ? stated carefully, ? often turns out to be a (nonempirical) mathematical truth.” Thus, if natural selection is a tautology, it is one in the same sense that a good mathematical proof is tautological. Referring to something as tautology generally means it is trivial. This broad sense easily encompasses non-trivial insights which are true by virtue of logical analysis, not on any empirical basis. Unless being true has suddenly become a bad thing, I’m comfortable with knowing natural selection and other mathematical models in biology can be constructed as a mathematical truths.

Comments

  1. #1 Mr. Gunn
    April 4, 2007

    Well put, and better explained than MarkCC. I was going to guess that the reason the tautology argument is still being used is because the creationists just haven’t read it, but then I saw the citations of the book on amazon. Dembski has cited the book twice. They’re read it, and they’re still advancing the argument.

  2. #2 John Wilkins
    April 4, 2007

    John Maynard Smith, no slouch at the odd mathematical model of things, once observed that in any theory with more than a few lines of algebra, there exists a tautology. It’s what you do with them that makes it a theory…

  3. #3 Richard W. Crews
    April 5, 2007

    I think I’ve asked this, here, before : Can we frame Evolution in a simple 3-6 word phrase that is positive and beneficial?

    To beat Republican Creationists at their own game – which is effective phraseology.
    It’s not survivors that survive (which charges up pseudomacho daddyRepubs), but what works best is in the long run.
    What we see is beauty is just survivor skills of all sorts, from the macho to the reproductive and nurturing. The flower is not for us, regardless how much we like it.
    The publicity war, which allows the political war on what shouldn’t even be debatable, is being won by the stupid side. Even the court battles they “lose” are winners to their cause, which turns out to be political.
    They are winning because of short phrases that imitate common sense.

  4. #4 Josh
    April 5, 2007

    I’m not sure that we win anything by putting out inaccuracies, either. The key is to learn to use mass media in ways that constructively engage the public, and leads them into a clearer understanding of how science actually works.

  5. #5 Flex
    April 5, 2007

    Richard W. Crews wrote, “Can we frame Evolution in a simple 3-6 word phrase that is positive and beneficial?”

    Well, one memorable sound-bite is worth a textbook of explaination. Even Ben Franklin knew that.

    The biggest trouble is that the most expressive models for evolution are typically those which require a pretty good visualization of an abstract concept. The ‘fitness landscape’ is a good visualization, but as you add parameters to the model it quickly moves away from the three dimensional image we have, which means that this model does contain inaccuraccies. But even the ‘fitness landscape’ visualisation, as good as it is, cannot be expressed in few words. I think.

    Let’s see though, I’m not too good at these sorts of things but:

    “A new branch doesn’t kill the limb” (To answer the question of “Why are there still monkeys?”)

    “Evolution is solar powered” (a true statement but startling enough to open a conversation.)

    “All evolution means is that species change to suit their environment, but environments also change.”

    Shorter, “Evolution builds on past successful changes”

    Shorter, “Change begets changes”

    OF course one difficulty is that it is possible that one of the reasons people fear evolution may be because they fear change.

    Well, that pleasantly killed a few minutes on a Thursday before a three day weekend. Maybe I can skate out now that it’s after 4. ;)

  6. #6 Treesong
    April 6, 2007

    The tautology issue is an artifact that arises when words are applied naively to a quintessentially dynamic situation.

    I suppose that Egnor is offended by the notion that according (to his reading of) the theory of natural selection, the e.g. cichlid fish species “causes” itself. This seems nonsensical, as it may be in the context of purely logical calculus.

    But a cichlid individual doesn’t exist as a category in a divine world. It lives “through” time — hatches, eats, reproduces, and dies. The individual that we see at time T2 is not the same individual that we see at T1. It is true that T2 may be the offspring of T1. It is only OUR painfully constructed and maintained nomenclature that says that the T1 adult is the same “thing” as the fish egg form T2. But that has to do with categories and systematics, not with the individual fish, which remain physicaly distinct. The parent cannot be said to cause the offspring.

  7. #7 Bilbo
    April 6, 2007

    I find the term “Republican Creationists” to be interesting. I’m not from Kansas. Has all the controversy over the Board of Education and teaching standards on Evolution in Kansas pretty much divided along party lines? I’m curious, because I’m a liberal Democratic IDist. However,I think the worst thing IDists can do is try to force the teaching of ID into public schools. All it does is increase skepticism and hostility among an already skeptical and hostile scientific community.
    I compare it to the cosmological theory of the Big Bang. Luckily, when it first came out in the mid-30s, creationists didn’t try to force public schools to teach it. Otherwise, I doubt if it ever would have received a fair hearing in the scientific community.
    By trying to force ID down the public’s throats, before we have a developed theory, we’re just shooting ourselves in the foot. And I think the results in Kansas have proved that.

  8. #8 Science Avenger
    April 7, 2007

    They are winning because of short phrases that imitate common sense.

    I’d say they are winning, inasmuch as they are, because most of the people on their side don’t want evolution to be true, and that is all there is to it.

  9. #9 Josh
    April 8, 2007

    I know of no Democratic politicians advocating for ID creationism, in Kansas or elsewhere. The IDolators on the KS school board were all Republicans, and were opposed by Democrats and moderate Republicans.

    I would also point out that the comparison of ID to the Big Bang is tenuous. Lemaitre derived the concept of the Big Bang from Einstein’s relativity, not from his Catholicism. It was verified not by Biblical reasoning but by tests of predictions from the theory.

    ID creationism has no theory (by the admissions of various advocates) and makes no positive predictions. It is derived from no actual data or overarching theory. The history of the arguments major advocates make and the history of those advocates clearly indicate that it exists only as a “wedge” to force religion into classrooms.

  10. #10 Bilbo
    April 11, 2007

    Josh: “I would also point out that the comparison of ID to the Big Bang is tenuous. Lemaitre derived the concept of the Big Bang from Einstein’s relativity, not from his Catholicism. It was verified not by Biblical reasoning but by tests of predictions from the theory.”

    We disagree on the origin of ID theory. I think it can be traced back to at least Plato. And nowhere in Behe’s book does he rely on “Biblical reasoning” to support ID.

    Josh: “ID creationism has no theory (by the admissions of various advocates)….”

    The problem here is that ID is a general theory, just as abiogenesis is a general theory. Within the general theory of abiogenesis are many specific theories (or hypotheses): RNA world; protein first; clay first; metabolism first; etc. And then there is the question of place of origin: Here on earth or on another planet. And then if from another planet, was it ejected in a cataclysmic event, or sent here by directed panspermia, as Francis Crick suggested it might have been.

    Within the general theory of ID are many specific theories (or hypotheses): Fred Hoyle’s view was that the first bacteria were designed by some sort of natural (as opposed to supernatural) designer, and then got here by panspermia, though he doesn’t make it clear if he thought it was an alien civilization or some sort of emergent mind; Mike Gene calls himself an ID evolutionist, though he doesn’t think there’s currently enough evidence to determine the nature of the designer; Joy (at telicthoughts.com) seems to favor EAM (endogenous adaptive mutagenesis), though you’ll have to ask her to explain it; and then there’s Old Earth and Young Earth Creationists. My view is that the designer was probably supernatural, and probably God. But if aliens landed here tomorrow and explained how they had designed the first bacteria and watched it evolve, I would feel ID had been vindicated.

    Josh: “…and makes no positive predictions.”

    Yes, making predictions of designers is a bit of a pain. I don’t know if you caught the news about Stonehenge back in February, but it was revealing of the problems involved. Here archaeologists thought they had the purpose of Stonehenge reduced to two possibilities: some sort of temple and/or some sort of astronomical calendar or observatory. Now they’ve found a village buried not far away, and a new hypothesis: Stonehenge is a cemetery. Of course they’re wrong on all three counts. Stonehenge is the first case in history of abstract art.

    But can ID make predictions? I’m not sure. Still waiting to see if Mike Gene actually has written “The Design Matrix.” If he has, my guess is that he’s made some predictions in it. Meanwhile, you could always check out his website, IDthink.net. Personally, I think the importance of ID is that it would allow biologists to think teleologically: Assume that the designer(s) was pretty darn smart, then when confronted with a feature that appears to be suboptimal or non-functional, use your assumption to motivate and guide your research. It might help. It might not.

    Josh: “It is derived from no actual data or overarching theory.”

    Data: features on the sub-cellular level look designed, and there aren’t good non-ID explanations of how they came about. That justifies an ID hypothesis, which is all I think IDists should claim at this point.

    Josh: “The history of the arguments major advocates make and the history of those advocates clearly indicate that it exists only as a “wedge” to force religion into classrooms.”

    Without debating the history of the arguments, let me agree that most of the ID movement’s motive was politco-religious, which I think is unfortunate. However, regardless of the initial motives, I think at least some of the arguments have validity.

  11. #11 Josh
    April 11, 2007

    “But can ID make predictions? I’m not sure.”

    Making predictions is what scientific hypotheses do. It has no positive content, and predictions published in a book that isn’t put through the standard peer-review process don’t do much for me. Having a hypothesis that makes a prediction is a pre-condition of being/having a theory. Evolution is composed of many subsidiary theories, from kin selection to character displacement, symbiogenesis to neutral theory. IDC has none at all. See Nelson, Paul: “Easily the biggest challenge facing the ID community is to develop a full-fledged theory of biological design. We donít have such a theory right now, and thatís a problem.” Also Dembski, Billy: “ID is not a mechanistic theory, and itís not IDís task to match your pathetic level of detail in telling mechanistic stories.”

    I don’t know what it’s supposed to mean that X “look designed.” There are plenty of very good explanations of cellular features, though “good” is obviously somewhat subjective. I consider an explanation that exists to be better than one which doesn’t, and that puts ID in a bad spot.

    The idea that space aliens solve the problem is silly. Who designed them? It displaces the problem without solving it. At best, space aliens or deities only replace explanations based on things we know exist (natural laws from chemistry, physics and biology) with things that may or may not exist. At worst, it replaces testable explanations (science) with untestable explanations (nonscience).

  12. #12 Stephanus
    August 1, 2009

    Mathematical equations, such as E = mc2, are not tautologies. The terms on both sides of the equation are defined elsewhere independently. The equal sign does not mean “is defined by” but rather equal to, establishing an equivalence. It doesn’t define one term in term’s of another. Acceleration and mass independently don’t equal force but their product MA as derived by Newton does, hence the equation F=MA isn’t a tautology. X=X could be a logical validity,mathematical redundancy or a logical tautology depending on the pragmatics or motive behind it

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