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Science

The Alleged Fallacies of Evolutionary Theory

In Issue 44, Peter Williams claimed to have found numerous logical fallacies in the writings of Richard Dawkins. His article has provoked this blow-by-blow response from Massimo Pigliucci, Joshua Banta, Christen Bossu, Paula Crouse, Troy Dexter, Kerry Hansknecht and Norris Muth.

The neo-Darwinian theory of evolution is the currently accepted paradigm to explain the history and diversity of life on earth. Yet, ever since the publication of Darwin’s Origin of Species it has been under attack on a variety of grounds. Some of these criticisms have been put forth in the philosophical arena, where evolutionary theory has often been accused of being incoherent or logically fallacious.

Perhaps the best-known philosophical criticism of evolution has been put forth by Karl Popper, who once claimed that “Darwinism is not a testable scientific theory, but a metaphysical research program” (Unended Quest, 1976). Famously, Popper retracted his comments, once it was explained to him that there was quite a bit more to the theory of evolution than he had understood from a cursory examination of the subject: “I have changed my mind about the testability and logical status of the theory of natural selection; and I am glad to have an opportunity to make a recantation” (Dialectica 32:344-346).

In Issue 44 of Philosophy Now, Peter Williams listed a bewildering array of eleven logical fallacies allegedly committed by evolutionary biologist Richard Dawkins in a variety of his writings. In what follows we reexamine each of the fallacies and comment on the extent to which Dawkins actually commits them. This article is not meant as a defense of Dawkins (who can surely take care of himself), but rather as a stimulating exercise tackling the logical framework of modern evolutionary theory and its real or perceived philosophical implications.

The Alleged Fallacies

1. Self-Contradiction – a statement that refers to and falsifies itself.

Williams quotes an open letter of Dawkins to his daughter, in which he advises her to think for herself, determine if a claim is being made on the basis of evidence or authority, and ask for evidence whenever somebody claims to know the truth. The problem allegedly is that Dawkins is conflating evidence with empirical evidence, from which it apparently derives that Dawkins also equates knowledge with scientific knowledge. Since the latter position is not itself based on empirical evidence, it follows that Dawkins contradicts himself by suggesting a course of action to his daughter that cannot actually be backed up by the very methods proposed by Dawkins.

We feel Williams is reading too much into Dawkins’ advice. Dawkins starts out by simply suggesting a sensible course of action to his daughter whenever faced with evaluating somebody’s claim to truth; he is not saying that his advice is scientific, nor is he equating knowledge with scientific knowledge. As for what counts as evidence, the American Heritage Dictionary defines the latter as: “the available facts, circumstances, etc., indicating whether or not a thing is true or valid.” From this perspective, most evidence is in fact empirical. The only exception would be mathematical or logical reasoning, although most people wouldn’t think of this as ‘evidence’ so much as a ‘reason’ in favor of a certain conclusion. Finally, empirical (but not necessarily scientific) evidence for Dawkins’ statement could be brought in: one only needs to compare the number of successful decisions that people make about, say, their finances based on reading their horoscopes vs. following the advice of a financial expert (if the latter is backed by empirical evidence on the performance of various portfolios).

2. Begging the Question - the fallacy of using the conclusion of an argument as one of the premises employed to establish that conclusion.

The problem here is that Dawkins seems to assume a naturalistic and gradualistic explanation for the diversification of life on earth. He claims that one can see that this must be true without stirring from one’s chair, as any other explanation can be ruled out on first principles. Williams concludes that Dawkins must take this philosophical (not scientific) position because he wants to exclude intelligent design a priori.

Indeed, Dawkins should not have said that one can see the truth of Darwinian evolution without stirring from one’s chair. Evolutionary biology is an empirical science, and it is only because of more than a century and a half of investigation that we have concluded that it is the best available explanation for the history of life on this planet. But there are two crucial distinctions that Williams fails to make: a) Darwinian gradualism is only one of a panoply of naturalistic explanations of evolution (others include Lamarckism, orthogenesis, and saltationism); while it is indeed the one currently most widely accepted by scientists, it is false to charge that it is the only game in town and is therefore accepted by default. b) Both Dawkins and Williams should make the all-important distinction between philosophical and methodological naturalism. Philosophical naturalism, the position that all there is to the world is natural phenomena, is indeed outside of science proper. But what all scientists espouse is methodological naturalism, the operational position that the best way to find a testable explanation for a phenomenon is to assume that only natural laws are at work. While creationists make a big deal of this alleged ‘bias’, in fact all of us behave as methodological naturalists most of the time. We are willing to bet (and this is an empirically verifiable prediction) that the next time that Williams’ car breaks down he will not go to church and ask his preacher to fix it; he will instead bring it to a mechanic, seeking a natural solution to the problem. Moreover, even if the mechanic should not find any remedy, Williams will not therefore turn to God, but will ditch the car assuming (reasonably) that the facts are simply insufficient to find the correct natural fix, and that he is better served by another means of transportation.

3. The False Dilemma - Two choices are given when in actuality there are more choices possible.

Williams quotes Dawkins saying that William Paley’s supernatural explanation for the complexity of life and Charles Darwin’s natural alternative are mutually exclusive. Williams cites Michael Poole as clarifying the difference between explanations in terms of agency and those in terms of mechanisms. The two do not have to be in contradiction, since a particular agent (say, God) could use a given mechanism (say, natural selection) to achieve whatever goal the agent sets forth.

We see two problems with Williams’ position: first, he equivocates on Paley. Paley was not talking about God just being the agent determining biological complexity, he thought of God as also being the mechanism: in other words, it is anachronistic to see Paley as a theistic evolutionist, since he was defending the classical Christian doctrine that God created humans and everything else directly, not through the action of natural laws. Second, while at a more general level Poole is correct that agency and mechanism are not necessarily mutually exclusive, ‘God did it’ simply does not qualify as a scientific explanation (or, in fact, as any sort of explanation), because it doesn’t add anything to the explanatory schema.

4. The Fallacy of Equivocation - a word is used in two different contexts and is assumed to have the same meaning in both contexts, when distinct meanings ought to be preferred.

Williams here takes Dawkins to task for shifting the meaning of the word ‘designoid’, coined to explain why the appearance of design in biological organisms is just that, an appearance. Dawkins says that there are natural objects that superficially look like the result of design, for example a rock looking a bit like the face of an American President. He claims that this is the same sort of phenomenon that induces people to think that, say, the vertebrate eye is designed. The problem is that the first type of ‘designoid’ is obvious (i.e., people immediately realize that the face was not actually carved), while the second is much more subtle and – Williams claims – therefore belongs to a different category.

We think Williams is partially right here: Dawkins did choose a bad example, and for fundamentally wrong reasons. The resemblance of a cliff outcropping to a human face is the result of entirely random causes (wind patterns, the consistency of the rock, etc.), while biological organisms are the outcome of two processes: mutation (which is indeed random) and natural selection (which is anything but random). That is why Dawkins’ designoids don’t cut it. However, Dawkins’ fundamental point can be rescued by simply using a better analogy. There are natural, non-biological, processes that convey the impression of intelligent design and provide us with a more closer parallel to evolution. For example, on many rocky beaches, pebbles are sorted by size going from the waterline towards the interior, in a distinctly nonrandom pattern. This is not because somebody got all the pebbles out of the ocean, carefully weighed them, and then constructed the beach. Rather, the pattern was created by the joint action of two processes: the (random) action of waves and the (nonrandom) effects of gravity.

5. The Non Sequitur – Comments or claims that do not logically follow from what has gone before, but that are presented as if they do.

Williams here leaves the field entirely to a quote from Stephen Barr, who accuses Dawkins of attempting to defend science from allegations of being ‘joyless’ and ‘arid’, while not recognizing that ‘the public’ raises those objections to atheism, not to science itself. Apparently, Dawkins does not seem to see the difference between science and atheism.

It is a bit difficult to make sense of what exactly the charge is here, and especially of why this would be an example of non sequitur. We take it that Williams’ intended target of criticism is the move from modern science’s discoveries to the philosophical position of atheism. Dawkins does indeed often state that his atheism is reinforced by the scientific understanding of the world: the more science finds out about nature, the less room there is for a direct intervention by supernatural entities. Now, if what Dawkins means is that atheism is logically implied by evolution, then he is surely wrong. On the other hand, to deduce philosophical (moral, existential, etc.) conclusions from the best available knowledge of the world is certainly not illogical, and seems to be the rational thing to do. The important distinction, therefore, is between an atheism that is informed by science (which is plausible), and one that is made logically necessary by science (which is illogical).

6. Special Pleading (double standard) - the fallacy in which one criticises others for falling short of particular standards and rules, while taking oneself to be exempt, without adequately justifying that exemption.

The alleged fallacy here lies in the fact that Dawkins on the one hand rejects ‘God’ as an explanation, on the ground that there is no way to tell where God himself came from, while at the same time accepts natural selection as a valid explanation of the diversity of life on earth, even though natural selection itself cannot explain where life comes from.

We see three problems in William’s position: First, natural selection was never meant as a theory of life’s origins, while ‘God did it’ clearly is. Second, Dawkins would be engaging in special pleading if he had not provided an account of how natural selection (not life) began, since the explanatory principle parallel to ‘God’ here is selection, not life (life is what needs to be explained by either ‘hypothesis’). But evolutionary biology does have an explanation for how natural selection comes into being: it happens as soon as there is a population of self-replicating, variable, molecules. No such explanation is available for God. Third – once again – ‘God did it’ is not an explanation, but a fancy way of admitting ignorance: an explanation is an account of mechanisms (such as natural selection), not a label to put on the facts.

7. Wishful Thinking - a fallacy that posits a belief because it or its consequence is desired to be true.

Williams comes really close to catching Dawkins (but not science in general) in flagrante delicto. Dawkins is cited by Williams writing that nobody knows how life on earth originated, but it must have been by natural causes.

If Dawkins is reaching that conclusion – as Williams alleges – because of his philosophical position of naturalism (i.e., atheism), then he is in fact engaging in wishful thinking (though no more than the other side when they say that life must have originated from an act of special creation). However, there is a more moderate interpretation of Dawkins’ statement: he is just being a good scientist in accepting as a matter of methodology that the only way to find a scientific explanation for the origin of life is to tentatively assume that there is one that doesn’t include supernatural intervention. One may not like the idea that science is limited to natural explanations, but it is hard to see what sort of experiments or testable hypotheses could possibly emerge from introducing a supernatural fiat into these matters. As an aside, we also point out that Williams’ statement that there is “a large body of scientific evidence against” a naturalistic theory of the origin of life is simply false (see, for example, The Emergence of Life on Earth: a Historical and Scientific Overview by I. Fry, Rutgers University Press, 2000.)

8. The Red Herring - A Red Herring is an irrelevant topic or premise brought into a discussion to divert attention from the topic at hand. Usually, the irrelevancy is subtle, so that it appears relevant to those not paying close attention.

This is really another version of the objection raised under fallacy #6, but with a different twist. Williams claims that the real problem of evolutionary theory is to explain the origin of catalytic proteins (enzymes), and accuses Dawkins of distracting his readers from it by introducing natural selection as an explanation of how enzymes became more complex beginning from a simple molecule.

Once again, evolution by natural selection is not, and was never meant to be, a theory of life’s origins. Ironically, it is the creationists who make a red herring out of this issue, since they keep misinterpreting the scope of evolutionary theory. Natural selection is (demonstrably) perfectly capable of changing and improving the catalytic actions of proteins, which is all the theory claims. On the other hand, it is true that we still don’t know how the first replicators originated; however, what is needed for a naturalistic theory of origins is that the first replicators were simple enough to originate randomly. This does not seem an inordinately unlikely supposition. Lastly, it is interesting that Williams introduces the concept of ‘irreducible complexity’ of proteins as if it were widely accepted in science. It is not.

9. Straw Man Argument - a type of Red Herring that attacks a misrepresentation of an opponent’s position. That is called to burn a straw man. It is a surprisingly common fallacy, because it is easy to misunderstand another person’s position.

The incriminating passage here is one in which Dawkins states that the difference between science and religion is that the former is based on evidence and ‘gets results’, while neither apply to the latter. Williams, curiously, takes this to be an attack on Christianity in particular, and responds that there has been a strong Christian tradition of valuing rationality.

First, Dawkins was taking aim at religion in general, not especially at Christianity. Second, the criticism was that religion is not based on evidence, which is not the same as accusing religious people of not valuing rationality. One can construe rational arguments in favor of the existence of God, but one cannot provide any evidence to back up such constructs. Science is an inextricable combination of rationality and evidence: without the latter, it would not be different from logic or philosophy. Lastly, while it is certainly true that there are great traditions of rational inquiry within Christianity, do we need to remind Williams that the Church always put very strict limits on such ‘free inquiry’? Just think of Bruno, Copernicus and Galileo. The scholarly tradition of the Catholic Church is surely well represented by the Jesuits (for example, they run the Vatican astronomical observatory in Italy), and yet it was the Jesuits who opposed Galileo and famously refused to acknowledge the observational evidence he was providing through his telescopes. It is hard to think of a better example of how differently science and religion approach the relationship between rationality and faith.

10. Ad Hominem – the fallacy of attacking the individual instead of the argument.

Dawkins, in his characteristic bluntness, likens people who believe in God to children who believe in Santa Claus. Williams takes this to be an ad hominem attack, and hence a logical fallacy. Williams then goes on, somewhat curiously, to state that even children are sometimes right, and that therefore one cannot dismiss childish beliefs altogether.

We chastise Dawkins for his language, which is sure to inflame and certain not to gain him much sympathy. On the other hand, this hardly qualifies as a fallacy because Dawkins is not using the ‘belief in God = childish thinking’ equation as an argument against the existence of God. On the contrary, he begins with the premise that God is a fairy tale and then deduces (in a perfectly logical manner, if one accepts the premise) that believing in God is as childish as believing in fairy tales. Of course children (or childish adults) can be right about certain things, but Socrates (in Plato’s Meno) convincingly argued that true belief without cause is nothing to brag about.

11. Poisoning the well - a form of ad hominem attack that occurs before the meat of an argument, biasing the audience against the opponent’s side before he can present his case.

Dawkins is once again taken to task for his language. In some of his writings, he alleges that no qualified scientist doubts the reality of evolution, the implication being that one should not pay attention to arguments advanced from people who do not believe in evolution, because they are not qualified on such matters.

As in other cases, we agree with the criticism of Dawkins’ language, which is clearly hyperbolic (heck, if one searches hard enough one can find qualified scientists who doubt quantum mechanics, by most accounts the best scientific theory of all time!). Dawkins can indeed reasonably be taken to be ‘poisoning the well’ here. However, we find Williams in turn to be rather disingenuous (and relying on an appeal to authority, a fallacy in itself) when he quotes three allegedly qualified and unbiased authors on his behalf: William Dembski, Jonathan Wells, and Thomas Woodward. All three are open Christian apologists, and therefore cannot seriously be considered to be ideologically unbiased (note that while Dawkins is an open atheist, there is a large number of religious people from many denominations among evolutionary scientists). Moreover, Dembski has degrees in mathematics and philosophy, Woodward teaches theology at a fundamentalist Christian school for ministers, and Wells has a degree in biochemistry and molecular biology. None of them are qualified to comment on evolution for the simple reason that their degrees are not in any of the organismal biological sciences. One of us (Massimo Pigliucci) has a Ph.D. in Botany, which is an organismal biological science, but he would hardly feel qualified to comment about the reasonableness of, say, quantum mechanics. Just because one has a Ph.D. one is not automatically qualified to pontificate on all topics, as much as one’s ego might incline one to think so.

Science, Philosophy, and the Limits of Logic

This entire discussion is based on the concept of logical fallacies. But reasoning can be logical, and even correct, at the same time that it is strictly speaking fallacious. For example, one of the classical fallacies is the post hoc ergo propter hoc (after that, therefore because of that), where one infers that the cause of a certain effect is a particular event on the basis of the fact that the alleged cause preceded the effect in short time (e.g., I woke up with a headache this morning; I drunk red wine last night; ergo the wine caused the headache).

It is important to realize in what (very strict) sense post hoc ergo propter hoc is a fallacy: if one wishes to say that it necessarily follows that if two events are temporally close to each other, then the first one causes the second one, this is obviously not true. We have plenty of examples of temporal sequences the elements of which are not causally connected (e.g., last night it also happened to be full moon, but that very likely had nothing to do with my headache this morning). However, it is perfectly rational to begin the investigation into causes based on correlations, which is exactly what science does. If I know that certain kinds of red wine (e.g., high in sulfites) are prone to cause headaches in certain individuals, and if I repeatedly observe that when I drink those kinds of wine I often develop a headache the following morning, then I am logically justified in tentatively concluding (pending further evidence) that my headaches really are caused by high sulfites levels in red wine (and I ought to stop drinking such concoctions).

It follows from all of this that science is inherently an approach that can lead only to tentative conclusions, while if one wishes Truth one is limited to the realm of logic and mathematics. Philosophy occupies an interesting middle ground between these two approaches: while a philosopher attempts to build bullet-proof logical arguments (i.e., she aims at logical truth of the formal kind), the premises of her reasoning can only be of two types (Hume’s famous ‘fork’). Either one starts with arbitrary or unfounded statements, in which case even logically tight reasoning leads nowhere; or one begins with empirical observations about the world, and philosophy therefore shares some of the limitations of science. A lot of ink and bad feelings would be avoided if people realized that human beings (with the exception of logicians) cannot attain Truth, but only more or less likely maybes.

This article was written jointly by Professor Massimo Pigliucci and the members of his graduate class on evolutionary thinking at the University of Tennessee, Knoxville. www.rationallyspeaking.org