Evolution *is* a Theory, and That’s a Good Thing

Conservative candidates are now routinely asked to take a stand on whether they “Think evolution is just a theory” or whether they are among the fallen who “Believe in evolution”. These exchanges nearly bring up my breakfast on their own merits and have the added disadvantage of mis-educating the public about the nature of scientific inquiry and theory.

The dismissive remark “Evolution is just a theory” implicitly equates “theory” with the spontaneous speculations of the guy four bar stools down from you whom the bartender has at last cut off. In science, a great theory — evolutionary theory, for example — is a serious intellectual effort to explain the data we can observe and to generate hypotheses about the data we can’t. Calling a biology professor “a noted evolutionary theorist” is a compliment in the scientific community, not an implication that he is stupid, misguided or refuses to accept reality.

The alternative to conservative politicians deeming evolution “just a theory” is for them to intone “I believe in evolution” or “I accept evolution.” These sound to my ear inappropriately similar to statements of faith, e.g., “I believe in the transmigration of souls”, “I accept Jesus Christ as my personal savior”. If “evolution” in this faith statement refers to the theory of evolution, then this is the wrong terminology. Scientists don’t believe in theories per se, they believe that particular theories do a good job explaining what has been established not through faith but via empiricism. If new data disconfirm the theory, a scientist wouldn’t say “It doesn’t matter, I have accepted such and so theory and with God as my witness that’s an end of it”. Rather any scientist worth his or her salt says the theory must be wrong and therefore has to be discarded or changed.

If on the other hand the word “evolution” in the statement “I believe in/accept evolution” refers to the observable data on whether evolution ever happens, this is also a conflation of the workings of faith with those of science. You can take a colony of drosophilia and let them fly through a maze, putting sugar at the end of a right fork in the maze and nothing at the left. In a few days, the flies who tend to turn right and get the sugar will be outbreeding those who tend to turn left and pretty soon you will have a colony of right-turning flies. At that point, you don’t “believe” that natural selection can happen, you have directly observed it as a fact. You don’t have faith in this context any more than you have faith that water turns to steam if you heat it to 100 degrees Celsius.

Journalists (e.g., debate moderators) could do a service to the political process and the scientific education of the public by asking the basic question differently:

“People have long tried to explain where the creatures on this planet, including human beings, come from and why they have the characteristics they do. We have data from our observations of living beings today, from the fossil record, from laboratory studies, and from a range of other sources such as the breeding and domestication of animals, and we want some explanation to account for it all. Do you think that these data are better explained by evolutionary theory or by creationism?”.


  1. Kate Baldwin says

    “These exchanges nearly bring up my breakfast on their own merits, but have an added disadvantage that hasn’t to my knowledge received much attention: They mis-educate the public about the nature of scientific inquiry and theory.”

    Totally correct in one sense — this way of framing the question does seriously mislead the public, and although I think your suggestion for a replacement goes a little far in the other direction, clearly “believe in” isn’t the right way to describe the thought process of someone who thinks the available evidence supports descent with modification through natural selection.

    However, quite wrong in another sense: this problem has received SCADS of attention! If you go to the National Center for Science Education website (http://ncse.com/) and search on the term “just a theory” you’ll get 10 pages of results, the top one (http://ncse.com/rncse/27/5-6/review-just-theory) being a 2007 review of an entire book with that title, Moti Ben-Ari’s “Just a Theory: Exploring the Nature of Science”. So be of good cheer — there are many others fighting this battle right alongside you.

  2. James Wimberley says

    Yes. Darwin published “The Origin of Species” – in 1859! – for people who recognized that the evolution of living things through deep time was a fact, abundantly attested by the fossil record, and wanted an explanation better than special creation. The explanatory theory, Darwinism, is that new species arise by descent and modification by natural selection, and it’s as true as anything in science. Asking politicians whether they “believe in evolution” is like asking them whether they believe in planetary motion. The only way of denying it is to negate deep time itself, and claim the geological and fossil record is an elaborate divine forgery: in other words, the totality of modern science is wrong.

  3. Keith Humphreys says

    Kate Baldwin: You made my day! Thank you for this encouraging news. I have amended the post accordingly and embedded your proposed “just a theory” link as well. I am also granting you 50% of all royalties and film rights that come from this blog post.

  4. Anon says

    The only way of denying it is to negate deep time itself, and claim the geological and fossil record is an elaborate divine forgery: in other words, the totality of modern science is wrong.

    I’m not sure that a claim of forgery necessarily means that science is wrong. An omnipotent god could create a universe which obeyed a discoverable set of consistent rules.

  5. Anomalous says

    And of course Newton’s idea of gravity is just a theory. When this was pointed out to some wing-nut politician his response was that he knew that and believed that objects fall to earth because God wills them to. You can’t argue with that, now can you?
    Now excuse me but I’m going to check out Kate Baldwin’s and Nescio’s links.

  6. Joe says

    Evolution is not “just” a theory. It is a magnificent theory. As James Wimberly pointed out, it was published in 1859. With a few concepts, Darwin affected research throughout what we today call the life sciences. Literally from anthropology to zoology. He made predictions about the nature of the fossil record that are still being confirmed today. He speculated on a mechanism of inheritance (got it completely wrong), but in the process anticipated Watson and Crick 100 years later. That’s an incredible accomplishment. This is a theory that has truly stood the test of time.

    No educated person should be deprived of an understanding of such a theory. Yet, when we dilute it by equating it’s validity with creationism/”intelligent” design, that’s exactly what we’re doing.

    I don’t think the Republicans really care about evolution one way or the other. The only reason they have embraced creationism/intelligent design it is that it feeds the paranoia of the fundamentalists and keeps them in the Republican party. The sad thing is the amount of destruction this strategy inflicts on intellectual inquiry.

  7. drkrick says

    Anon – True, but that’s not the argument. Certain evangelicals seriously argue that god manipulates the appearance of the universe as a “stumbling block” to those who are “insufficiently faithful” enough to ignore evidence in the face of what they consider conflicting scripture. The existence of that kind of trickster god would make a discoverable set of reliable rules impossible.

  8. marcel says

    Of course, (some) scientists have observed evolution in the laboratory and others have observed it in the field, but those who do not study relevant parts of biology, including not only physicists, and most chemists but also many biologist, are just like the rest of us. They must take evolution on faith. What humans know, as a group, is too great for any individual to know and certainly too great for any one to study outside of books or the lecture hall in all its gory detail. We have a division of labor. I happen to leave the study of (and expertise on) many things to others: evolution, relativity, quantum-mechanics, effectiveness of different drugs, climate change/global warming and the role of humans therein. I rely on experts, for the most part credentialed experts, because in these fields, as far as I can tell, they have a better record with regard to prediction and accurate description than others. The rough and ready rule guiding whose expertise I accept is a reliance on scientific method.

    Science is not so much a body of knowledge but a set of techniques for generating new “facts” and for correcting mistakes about what is accepted as fact. The technology that has been developed by relying on scientific knowledge is persuasive. Does this mean that science is infallible? Of course not, but in the long run, I expect it to be self-correcting. Moreover, the knowledge that it generates is more reliable about those areas with which it is concerned than anything else we have.

    So, do I, a lay person, believe in evolution? Yes, both because the explanations and descriptions I have read sounds plausible and because the people I rely on to study it and to know more about it than I tell me that it is the best description available for the relevant phenomenon. Is this a matter of faith? Largely yes, in those people and in (my understanding of) the scientific method and scientific endeavor, not so much in evolution per se. Ditto for relativity, particle physics, climate change, etc., etc.

  9. Anomalous says

    @Joe-Well put. And your last paragraph is not only true but the tip of an iceberg running through the GOP. “The Southern Strategy”, opposition to abortion rights, gay rights, gun control, imigration issues, on and on as well as denegrating accepted science, the GOP beats these drums because they stir up their irrational/ignorant base while (they feel) costing their task masters, the well heeled corporations nothing. What does Dow Chemical care if Billy Bob and his tribe believe the sun goes around the earth and that the earth is 6,000 years old? Hey, the dumber the rubes are the easier they are to fleece. Youbetcha!

  10. says

    This whole post seems to based on a very narrow reading of “believe”. I believe it’s not raining outside my window.

  11. says

    ‘At that point, you don’t “believe” that natural selection can happen, you have directly observed it as a fact.’

    False–in the experiment described, you are demonstrating genetic changes in population due to differential reproductive fitness based on *artificial* selection. Not the same thing, though obviously closely related. (Don’t feel bad–Lisa Simpson made the same mistake in a discussion with Ned Flanders.)

  12. Drew says

    I really don’t want to get all Hitchensesque here (pace MK) but would it be inappropriate to ask a politician if he believes in the ‘theory’ that Jesus Christ died on the cross and on the third day rose from the dead and then ascended into heaven to sit at the right hand of God?

  13. James Wimberley says

    Marcel: unless you have graduate-school mathematics, quantum physics is a theory that has to be taken on trust, by the indirect methods you describe. But Darwin is pretty easy reading, and his theory, being qualitative, doesn’t require mathematics. There’s no excuse for sceptics not to read the book.

  14. Ralph says

    I just finished listening to a set a lectures on the history of early christianity. the presenter made an interesting point about pagan religions (and judaism to some extent). he said they were based on actions, not belief. there were rules about how to behave (rituals to propitiate certain gods, sacrificing, etc) but not a requirement to accept/declare a creed. and the pagan religions were inclusive, you could worship many gods without offending any of them; the concept of heresy did NOT exist.

    but then christianity came along and stipulated that shared beliefs were crucial. to be christian, one had to believe certain things about the nature of jesus and if one did not, he/she was branded a heretic….that is, someone who was trying to undermine orthodoxy, which is Right Belief and Truth. moreover, these required beliefs were exclusive: accepting Jesus as the savior means rejecting all other gods.

  15. Benny Lava says

    Anomalous hit the nail on the head. The theory of relativity is ONLY a theory. Does that make it wrong? Do we need to teach alternative theories in school because it is ONLY a theory? Heck, numbers are only a theory; ever heard of the Number Theory?

    The dismissal of evolution because it is only a theory is a way to deceive people who are not well versed in science.

  16. Ralph Hitchens says

    Benny & others hit the nail on the head. “Theory” has a different meaning in science than it does in other contexts. You don’t dismiss a theory propounded by a scientist as easily as you might dismiss a theory put forward by a sportswriter or political analyst.

  17. marcel says

    @James Wimberley:

    I guess I was not clear. I meant that there are a whole lot of things that I take on faith, that I must truthfully answer “I believe.”

    Many are scientific in nature.

    By and large, I place my confidence in what I understand the scientific consensus to be with regard to the natural sciences.[1],[2]

    Especially, but not only, because I recognize that any consensus is provisional and may come undone, I don’t believe there is anything wrong with this, that I need to apologize for anything.[3]

    All I am saying is that often faith in something is required to get on with both every-day life and other things that one deems more pressing or important. But one should choose how to place your faith based on evidence. Over the last several centuries, and especially over the last 150 years, the institution that we call science has provided a great deal of evidence that where you cannot intelligently judge independently, it is reasonable to take it on faith, and almost always unreasonable not to.

    [1] I am here using “consensus” in its colloquial rather than conventional/historical/traditional meaning, i.e., preponderance of opinion.

    [2] As someone with a PhD in economics, I think I can (a) trust to my own knowledge rather than experts, and (b) say with some authority that the social sciences justifiably have less intellectual authority about their subject matters than do the nat’l sciences about theirs.

    [3] And just because I am willing to accept scientists’ consensus about fact does not mean that I necessarily march in lock-step with any on policy. I have a strong predisposition towards prudential policies, whether with regard to nuclear power or GMOs. With technologies whose harms and weaknesses are not well understood, I am usually quite willing to say, “Human civilization has done without these technologies for millenia. We can wait a few more years or decades until the perils are better understood.”

  18. says

    I was happy to see folks here mostly writing “it’s not just a theory, it’s an awesome/well-confirmed theory,” rather than using the following sophistical ploy that’s become fashionable: “Yes, it’s “just” a theory, but ‘theory’ means a well-confirmed set of hypotheses!” That bit of nonsense has really caught on. Granted, it’s less harmful than most creationist trickery, but it just ain’t so. ‘Theory’ has no such specific meaning, outside science nor within it. ‘Theory’ is very vague, but roughly suggests something bigger than a single hypothesis…but that’s about it. Granted, ‘theory’ may have begun to take on the new connotation…but that’s *not* the way the term has typically been used, and it’s not how it was used when the response first gained currency.

  19. Ed Whitney says

    This post stands in a close and interesting juxtaposition with Mark’s post about the tension between libertarianism and democracy. Something about science which I think grates at many cultural conservatives is its undemocratic nature. One guy’s opinion is not just as good as another guy’s, especially if the latter has spent years learning the basic principles, mastering the nuances of research, and examining and generating a large body of data concerning the topic being debated. It is elitist to say that the average fellow at the Tea Party rally does not have an opinion deserving of equal respect with that of the biologist who has studied geology, paleontology, genetics, embryology, and comparative anatomy. People like Ann Coulter deserve to be told, “Shut up, lady, you have no right to talk” when they try to give their opinions about Darwin and evolution. The right to respect for one’s scientific opinion has to be earned; it is not a birthright. Rick Perry does not get to express an opinion about the science of evolution and have it respected. It does not matter how many votes he can gather for his position.

    Science and capitalism are undemocratic and inegalitarian, but not in the same way. To compare and contrast would require a whole essay which I hope some RBC member will post in the future. If you see an analogy that states “Scientist is to scientific opinion as property owner is to political opinion,” you should reject it, bur for reasons that require some elaboration.

  20. Jack says

    No, evolution is not a theory; it’s a fact. It’s the theory of evolution, which is a theory, but that is only a theory about how evolution (a fact) occurred.

    Think of it like a police investigation into the cause of an automobile accident. The accident is a fact. You have smashed cars, skid marks, broken glass. The police investigator’s job is to put forth a theory of how the accident occurred — a theory of the accident — but the fact of the accident is never in doubt.

    Evolution is a fact.

  21. marcel says

    @James Wimberley:

    One more thought occurred to me, about reading Darwin. What Darwin does, for us lay types, i.e., those who do not have the training and/or background to evaluate the evidence competently and independently, is to establish the plausibility of evolution. Many things are plausible that aren’t so. I still have to outsource that evaluation to someone whom I trust, i.e., have faith in. And in my case, for reasons enumerated in previous comments, that is the scientific establishment. They say it (evolution) is so, i.e., that is the consensus among those who (I believe) are in a position to reasonably make that judgement. Well, that is, that has to be, good enough for me. But it is still, a matter of faith.

    I am not arguing that creationists are in any way reasonable. But I do think we should recognize where their fault lies. Not in the issue of faith (“What Yahoos!”), but in their judgement about how you decide where to place your faith and how to respond to things that You Just Can’t Stand. When my daughter was not quite 3, and my then 5 year old son had a typical little kid (little boy?) fascination with dinosaurs, she announced one day, “I don’t believe in dinosaurs. And I especially don’t believe in tyrannosaurus rex!” This attitude is funny, and understandable and even reasonable in a toddler. Not so much in an adult, and especially not so in hordes of ‘em.

  22. Keith Humphreys says

    Marcel: There is wisdom in what you say and I appreciate your nuanced analysis very much. I picked the drosophila example because when I was at the University of Illinois I decided to watch the experiments of the flies in the maze as conducted by Dr. Jerry Hirsch (a card-carrying genetics expert, which I am not). But I might easily not have done that, in which case I would be taking it on faith that Jerry could do what he said he could do with drosophilia.

    There is a difference though in “faith” that a scientist is not daft or dishonest and religious faith in that, at any moment where one wanted personally observed truth, one could get it from a scientist. That is not true of religious faith (which not incidentally I don’t disparage at all, I just would say it is different than the “faith” – maybe trust is a better word — I have that respected scientists can demonstrate for me the empirical realities that they report in their research if I asked them to).

  23. rachelrachel says

    @James Wimberley:

    “The explanatory theory, Darwinism, is that new species arise by descent and modification by natural selection, and it’s as true as anything in science.”

    The term “Darwinism” is used to mean all kinds of things by all kinds of people, but your definition is just about the most minimalist. By your definition, a guy like Michael Behe would be a Darwinist. In fact Behe doesn’t regard himself as a Darwinist and the folks who do embrace that label don’t see him as one of them, either. For those of you who aren’t familiar with him, Behe is a Ph.D. biochemist, “Intelligent Design” proponent, professor at Lehigh University and author of a couple of bestselling books. If I may risk oversimplifying his position, Dr. Behe accepts common descent and believes that natural selection is an important part of how living things evolve. But he doesn’t believe that the Darwinian mechanisms are capable of everything and that somewhere the Hand of a Designer must have intervened.

  24. James Wimberley says

    rachelrachel : I don’t follow you. I characterised Darwinism as the proposition that “new species arise by descent and modification by natural selection.” (Italics added.) It doesn’t leave room for another mechanism. (In fact it’s only partially true on bacteria, which don’t have sex and can exchange genes directly, so the notion of descent is problematic.) Behe denies the adequacy of natural selection applied to random mutation and sexual gene shuffling, which makes him IMHO an anti-Darwinist.
    Darwin realised that to prove the adequacy of natural selection requires an accumulation of data, and the solution of hard cases like the sophistication of the eye. He wasn’t just dithering for 20 years after having his insight, he was amassing the examples that fill The Origin of Species. The evidence for his theory has just gone on getting stronger.

  25. Sebastian Dangerfield says

    Um, “evolution” is a fact. Empirically observable fact. There is copious evidence of change over time. The theory relates to the mechanism — to wit, the theory of evolution by means of natural selection (with random genetic mutation paying a significant role). This also should be gotten right. “I believe that the theory of natural selection best explains the observable fact of evolution” would be a more appropriate formulation.

  26. Sebastian Dangerfield says

    (Sorry Jack, you beat me to it; should do better than skim the comments before posting my two bits.)

  27. says

    It doesn’t make must sense to quibble about whether evolution is a theory or a fact. It’s definitely a theory…a very well-supported theory. And the more well-supported a theory is, the more likely it is to be (or, rather, represent) a fact, i.e. to be true. True propositions accurately represent the facts; the relevant bits of true theories are true propositions; and so those propositions correspond to/accurately represent the relevant facts.

  28. Sebastian Dangerfield says

    It most certainly makes sense to distinguish the data (change over time) from the explanation of the data (change over time that is brought on by means of natural selection). Lumping both together as “evolution” is inaccurate and harmful. It does not inform people. It in fact makes them less informed. Evolution means simply: change over time. This happens. It is not open to any debate that this happens. It’s apparent in the fossil record and it’s apparent in the lab with species — usually insects — that reproduce and turn over generations rapidly.

    To distinguish the observable facts from the theory that attempts to explain the facts is essential. It’s critical to understanding the most basic features of scientific inquiry. It is essential to clearing away the layers of bullshit that cover the essence of the “debate.” Failing to observe that distinction makes people less informed.

  29. says

    I would be in Jack and Sebastian’s camp. Perhaps, the fact of evolution would be better communicated by calling it a theorem, rather than a theory. Point being, if I remember my tenth grade geometry clearly, it is a “statement” or hypothesis for which a proof exists.

    If intelligent design advocates have any credibility, it might go to what Darwin did not address, namely how the process of life got its start. They could postulate that whatever that impetus was, laid down the markers for the inevitability of natural selection. Even many scientists awed by the wonders they observe maintain an ardent religious faith that is a candidate for filling in such blanks.

    Of course, there is significant work in the biochemical labs these days aimed (apparently) at filling in whatever blanks might exist, based on scientific observation and experiment. So you pick your poison.

    As for the educational politics involved, the type of revisionism that results in texts giving any scientific credence to intelligent design (beyond noting the existence of that hypothesis) commands none of my sympathy. But neither does the revisionist history that has been plugged into children’s textbooks in the name of diversity, or multiculturalism, or whatever the feelgood phrase of the moment might be. When you do that, you open the door for creationists to lobby for their favorite “theories.”

    I’m with D.H. Fisher – let’s be very disciplined about teaching our kids the historic truths, be on guard against fallacies of all kinds, and teach kids to cultivate the chops to form their own opinions and most important, the curiousity to pursue the subjects that interest them.

  30. J. Michael Neal says

    Redwave, you were fine until you started talking about revisionist history. Revisionism is a critical element in the study of history, just as it is in science. With research, we develop a better understanding of what happened. For those interested in the history of World War II, as well as a lot of other things, the opening of the Soviet archives in the 1990s led to a huge wave of revisionism that showed that a lot of what had been taught up to that point was bunk.

    The same thing has largely happened in American history, which seems to distress you. It isn’t due to archives opening, but rather because the view points of a broader set of people are considered. For instance, blacks had a lot less reason to think that the American Revolution was a great thing, because it categorically did not bring freedom to most of them. Unless you want to argue that their viewpoint has no value, teaching that the Founding Fathers, many of whom continued to own slaves, believed unequivocally in freedom is a lie. They didn’t. Teaching children otherwise is lying to them. The same thing is true about westward expansion, starting with Columbus. There is a large set of people for whom that expansion was a catastrophe. Pretending otherwise is dishonest.

    Complaining about revisionist history, as opposed to a particular piece of revision, is ignorant nonsense. Revisionism is both necessary and beneficial if one believes that historical accuracy is important. Diversity, in this context, means that if a given set of historical events were good from one perspective but bad from another, teachers must present both of those perspectives. If that means that some people’s views of the righteousness of their country are challenged, then that’s what needs to happen.

  31. James Wimberley says

    There’s a problem over the word ““revisionism”. In “Holocaust revisionism”, it’s denialism lite or full strength; trying to brush away or minimise inconvenient truths about the past. In other cases, it’s bringing inconvenient truths to light, as with “revisionist” history on the founding of Israel. As a term of abuse, Redwave, it fails through ambiguity.

  32. Anomalous says

    @Redwave- I think I’m correct in saying tha “Intelligent Design” falls under the definition of hypothesis. It is a proposed idea for an unexplained phenomenon. Or at least the proposers of the hypothesis claim it is here to fore unexplained. The thrust seems to be: ‘Here’s sumpthin’ your high an’ mighty scietific thinkers haven’t explained yet and we say this is how it works and you can’t prove us wrong so there!’
    Someone once observed that as sciencentific understanding has developed and perfected more rational explainations for previously what has only been seen as mysteries and magic, the things that are cited as ‘the will of God’ have receded to farther reaches of time and space. Of course in the end the answer may be that it’s all God but I think that runs counter to our current crop of bible thumpers desire to keep God in their breast pocket so He can work their will and dance to their tune.

  33. Barry says

    Ed Whitney says:

    “This post stands in a close and interesting juxtaposition with Mark’s post about the tension between libertarianism and democracy. Something about science which I think grates at many cultural conservatives is its undemocratic nature. One guy’s opinion is not just as good as another guy’s, …”

    I disagree – if there’s one common thread on the right, it’s bootlicking towards their ‘betters’. It’s *particular* pieces of science they don’t like.

    For example, bring up neoclassical economics, and watch the Faithful fall to their knees.

  34. ezra abrams says

    as a practical matter does it matter if you believe in evolution ?
    Seriously, aside from antibiotic treatment, how does evolution affect anything you do ? Does it change your commute, your sex life, what sport your kids play ? (well, I guess it might lead you to encourage your kids to take chemistry, astronomy and physics more seriously then some small part of biology)

    I’m not trolling, and I’m quite liberal, and given all the evidence – dsDNA condensed by histones or histone like proteins in eubacteria, lipid bilayer membranes with conserved signal transduction cascades, etc etc….

    But seriously, does it actually affect anything you do in the world ? I suppose the only way it does is if you don’t believe in evolution, you hang out with that sort of people and get some other wierd ideas