Creationist Canard #1 : "Evolution is a theory, not a fact"

I had a long letter to the editor published in the Tennessean, as part of a segment on the question "should you take your kids to the Creation Museum?" I receive a fair amount of e-mail. This has motivated me to put up, so that I can reference it from now on, my own rejection of a couple of creationist canards. Doubtless you can find huge numbers of rejections of this elsewhere, since these are canards that creationists bring up all the time.

"Evolution is a theory, not a fact."

Strictly speaking, that statement is true. However, this statement is always raised by those who would then take it to mean that it is reasonable to doubt that evolution happened, that evolution is just somebody's idea that caught on rather than something that is supported by mountains of evidence.

The problem is that the uses of the term "theory" and "fact" do not mean in science what most people think they mean. This is true particularly of theory.

Evolution is a theory, not a fact. But so is gravity. If I am standing still on solid ground, holding a ball, and let it go, would you doubt that it will fall down? No. That would not be reasonable. How do we know this? Indeed, how can we predict the rate at which it will fall? Well, we have the theory of gravity, which we can use to predict what the ball will do. And our predictions will be right-- although not perfect, if we don't take into account air resistance. Gravity is a theory and not a fact, but you don't doubt that a dropped ball falls down. It is no more reasonable to doubt that species developed from other species through a process of random mutation filtered by natural selection, as explained by the theory of evolution, than it is to doubt that a dropped ball will fall down, as explained by the theory of gravity.

A "fact" in science is something very low-level. Facts aren't the exalted high and mighty things, the ultimate truths, that are implied by the statement in the title of this post. A fact is something like "at such and such time on such and such date, my detector on such and such telescope registered this many counts from this star." Or, "this sequence of bases show up at this position on the chromosome of this organism." Or, "this fossil was found sitting in this layer at this position on Earth, and can be described as follows."

Facts are data. Facts are "truth," but they aren't "Truth." They're the basic, low level things. They are the raw results of experiments or the raw observations made about the world. At their base, they don't include any interpretation-- not even corrections for instrumental efficiencies or the like. Facts are the bricks on which science is built, but nothing more than that. They are simple, small, individual things, not particularly meaningful by themselves until we start thinking about them.

In common parlance, "theory" is a synonym for "speculation." That is not at all what it means in science. In science, a theory is much more than that. It's not just somebody's idea; it's something systematic and testable, a framework for understanding a range of natural phenomena. That something is a theory does not indicate that it's weak, on shaky ground, or simply somebody's opinion. In science, when something is a theory, it indicates that it's a systematic set of ideas that have some depth to them.

Theories explain facts. A theory is a systematic and (to a greater or lesser degree) quantitative model about how some limited range of natural phenomena work. Einstein's Theory of General Relativity is a model that describes how massive and massless objects interact with spacetime and with each other simply as a result of their mass (and energy density). It says nothing about supply and demand in economic systems, it says nothing about the evolution of the species, it says nothing about the interaction of charged particles via the electromagnetic force; it's just gravity. Einstein's General Relativity is a great theory; why? Because it explains a lot of facts. Newton's theory of gravity is also a good theory, but not as good. Why? It also explains a lot of facts, but makes some wrong predictions; Einstein's gravity explains more facts. Where Newton's theory works, the two theories make the same predictions.

Is Newton's theory of gravity wrong? I would rather say that it is incomplete.

Is General Relativity right? Well, I wouldn't come out and just say that. Indeed, there are reasons that most physicists today believe that General Relativity is also incomplete! However, it works very well in every regime we've been able to test it, so for daily purposes, we treat it as if it were "right." This doesn't mean we think it's ultimate truth. However— and here is where creationists make a mistake— the fact that we think General Relativity must be wrong in some cases does not lead us to doubt the predictions it makes for the situations where we know it applies.

Evolution is not a fact. Indeed, the theory of evolution we have today we know is incomplete, because there are still some doubts about some of the details. But the overall picture is absolutely as rock solid as the overall picture we have of gravity; indeed, while the predictions of GR are more precisely confirmed, I would say that from a descriptive point of view, it's likely that our theory of evolution is closer to reality than our current theory of gravity! Creationists would take the debate and investigation that is going on in order to further understand evolution as evidence that there is doubt about evolution itself. That is no more true than taking the Apollo project, which is probing for the limits of General Relativity, as evidence that there is doubt that if I drop a ball, it will fall down.

There are good theories, theories that have been superceded by better theories, and discarded theories. Evolution is a great theory; it explains a mountain of evidence, and it gives us a picture of the history of life on Earth and of a lot of other things in Biology. So many things are explained by our theory of evolution that it's just not reasonable to doubt it.

Evolution is a theory, not a fact. Yes, that's true, if you know what you mean when you say "theory." If you say "evolution is speculation, not fact," then you are very wrong. If you mean the latter by the former, then you are very wrong.

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very good, but a couple of nitpicks:

you might want to also mention that evolution is a fact as well as a theory: we (well... not me, but some scientists) have observed it happening. These facts are consistent with the theory, which is one reason why it is believed.

also, not all facts are created equal. Some are more trustworthy than others, and I think that's an important thing to mention.

Overall quite a good post, even if it is old territory.

Yes, it is a good post, but I would phrase it differently.

Gravity is a theory and not a fact, but you don't doubt that a dropped ball falls down.

I would call gravity the process and phenomena and gravitation the theory (theories). And we can observe the process by individual facts such as acceleration of masses et cetera.

Likewise, evolution defined as "common descent" is a process and it implies nested hierarchies among phenomes (genomes, cell types, organs, ... , species). And we can observe the process by individual facts such as fitness (the number of viable offspring produced per unit time for absolute fitness) and population descriptions of alleles et cetera.

And of course this is at least as incomplete and constrained as general relativity. Lateral genetic transfer makes a mockery out of the biological species concept (more a fuzzified bush than the customary tree), while I guess one can still describe inherited genes and organelles, et cetera.

Oh, and this would tie in with testability as well. A common description of a falsification of evolution would have been if early biologists found rabbit fossils in Cambrian strata. The nested hierarchy description would break, more specifically common descent of fossil characters.

So while the creationist asks for Truth, we can answer with facts and processes.

By Torbjörn Larsson, OM (not verified) on 11 Jun 2007 #permalink

I disagre. Evolution IS a fact. Facts do not have to be completely understood to assert that they are facts. Washington was the first US president is a fact. or is it? all we have is a written record. it all agrees, sure. but how do we know it is not an elaborate hoax? eh? were YOU there? what did he have for breakfast on his 245th day in office? don't know? aha, not a "fact" then is it.... Absurd, isn't it?

On the other hand, "natural selection" IS indeed a theory to explain the evolution of species.

You can dicker about the specific use of language. However, we all agree when creationists say "Evolution is a theory, not a fact," they think that "theory" means "speculation" and that therefore it's somehow in doubt. The point of what I wrote is that *that* is wrong.


Thanks for writing this. So much of the science blogs are just preaching to the choir and often assume knowledge that those not versed in biology probably wouldn't have.

In this canard, Dr. Knop correctly downgrades the term true and the value of fact in relation to science. An item cannot be proven to be TRUE. A fact is only as useful as far as it can be reliably counted upon to avoid falsification. The ball fell, is a fact insofar as there is an absence of countering forces, whether seen or unseen. Balls can be made to float in magnetic fields or in gusts of air. Outside forces must be discounted or explained to continue to assert the fallingness of balls.

In order to prove something is false only one point or possibility has to be shown incorrect. For instance, if I were to posit the statement that all cars are red, you would only need to find one blue, or any other colored car to disprove the statement.

To prove something to be true, one must examine every possible and potential falsifiable possibility and dismiss them. It is impossible to test every possible outcome so it is technically impossible to prove something true.

It is interesting that those supporting evolution are claiming that evolution is a fact and is true. When it is correctly pointed out that no theory can be proven to be true, the most common response is the Tommy Smothers huffy, Well oh yeah?!

The true (pardon the pun) debate should be over whether any tenants of evolution have been falsified. For instance recall the population explosion of minute mammals theory that supposedly followed the extinction of the dinosaurs. This was the mechanism which fueled an evolutionary push that resulted in larger mammals, including monkeys and humanoids.

Recently geologists and anthropologists reported that no such population explosion occurred. Now the theory of evolution has suffered two falsifications. That does not prove that the entire theory is wrong, but those problems must be re-examined and new explanations developed.

Evolution is replete with such contradictions. The DNA problem discussed in the other canard is seemingly one of the most devastating problems. The good news is that evolutionists will not want for employment.

Thank you for your consideration.

By JIm League (not verified) on 13 Jun 2007 #permalink

Dr. Knop correctly downgrades the term "true" and the value of "fact" in relation to science.

That is a misinterpretation. A theolog can argue about what "Truth" is. A philosopher can argue about what "truth" is. But in science people deal with observational facts, i.e. what can be observed. That is real and consistent, as you yourself note. (""The ball fell," is a fact insofar as there is an absence of countering forces". I.e. we observe the ball falling in such cases, and that is the fact.)

Theories may or may not describe 'ultimate reality'. [It is not essential here, but in fact there are expectations that there is an underlying "theory of everything" for theoretical reasons.]

But until we know they do that, their truth values are relative. For example, in classical mechanics it is true that an object approaching infinite kinetic energy is approaching infinite speed, while in special relativity it is true that it is approaching light speed. The later is also observationally true.

It is impossible to test every possible outcome so it is technically impossible to prove something true.

This Baconian view of science is very convenient for people that believe in Truth. Unfortunately this is not a current or viable idea of science.

The description "prove" can be debated since it is what mathematician does within formal theories (which taken in isolation admits a kind of absolute truth). The more common terms are to make an observation and to show or test a theory.

One view of the methods of science is that successful testing culls false theories. The one currently remaining is correct beyond unreasonable doubt on the observations at hand.

By Torbjörn Lars… (not verified) on 13 Jun 2007 #permalink

For instance recall the �population explosion of minute mammals� theory that supposedly followed the extinction of the dinosaurs. This was the mechanism

What mechanism? You are describing an hypothesis among others of what could have happened after a specific extinction. They are all compatible with evolution because we don't have enough facts for a definite model. So there was no way to use observations to make a falsifying test.

I don't think you got it correct either, after the extinction whole ecologies are destroyed and it would take a considerable time for populations to grow and stabilize. AFAIK what some people expected to see was an increased speciation to fill vacant niches.

But in fact, that isn't what seems to be observed, at least if you extrapolate on extant mammals.

"Challenging the 'conventional wisdom' that mammalian diversity is the product of an opportunistic radiation of species after the dinosaurs were wiped out at the end of the Cretaceous 65 million years ago, the authors instead identified two broad periods of evolutionary expansion among the mammals: an early event 100-85 million years ago when the extant orders first appeared, and a radiation of modern families in the late Eocene/Miocene. A key point is that there is no change in rates of taxon formation across the Cretaceous/Tertiary (K/T) boundary�mammalian diversity was rich before the dinosaurs disappeared." ( See the second figure in )

[Note: The discussed paper is debated, much because it only looked at extant lineages, but IIRC also because it confused observable minimum age for speciation with averages as in the figures.]

This was the mechanism which fueled an evolutionary push that resulted in larger mammals, including monkeys and humanoids.

No, large mammals were already in place before the C/T extinction, preying on dinosaurs. ( )

And there are no "humanoids" in biology, that is a term describing anything resembling a human shape. The earliest hominoids (including lesser apes to leave your monkeys) are about 25 Myr old and where still small. Since the K/T boundary is 65 million years ago, it is ridiculous to claim that your unspecified "mechanism" was so delayed and still drove speciation.

Recently geologists and anthropologists reported that no such population explosion occurred.

Since geologists study geology and anthropologists study human culture, that would be quite a feat. You are probably thinking of paleontologists.

The DNA problem discussed in the other �canard�

I see you have a sense of humor and are able to laugh at yourself. You are going to need it. :-)

By Torbj�rn Lar… (not verified) on 13 Jun 2007 #permalink