There is a common proposition among those that, generally for religious reasons, don’t like evolution, nor believe that it’s true, that “evolution is just a theory, and not a fact”. Many others have explained why this is patently false, but I’d like to point out that one of the problems lies in the language as used by everyday people, and as used by scientists, which confuses the matter for those who, for whatever reason, have no experience of the ways of science.

This graph shows a summary of the differences between a ‘theory’ as a lay-person understands it, and a ‘theory’ as it’s used and understood within scientific circles, with some other common concepts of levels of knowledge for comparison¹.

In the above diagram, we see the difference between an “everyday” theory, and a “scientific” theory. In ordinary use, a theory is little more than a guess, and it’s not necessarily based on any actual evidence to lend support to it. A theory as it’s used in the everyday sense is closer (but not necessarily up to the same standard) as the scientific concept of a hypothesis.

A hypothesis is a question posed about a certain avenue of investigation that can be experimentally tested, and if it’s found wanting, either modified to fit the new evidence if the change required is minor, or discarded completely if it’s so far from the observations that there’s no hope of reconciling it.

Another thing one might notice from the diagram is the difference between an “everyday” fact, and a “scientific” fact. In everyday use, a fact is something that is taken for granted as a truism, even though the person claiming it may have little or no other experience other than the direct observation of even just one occurrence, and there’s no reasonable expectation to assume that it isn’t true. This is generally acceptable for everyday use.

For scientific purposes, a fact must have far more than just one piece of evidence to support it: it should have many tested, examined and documented examples of evidence, and each one, on it’s own, should agree with the hypothesis that it is to validate. Science requires a far higher level of agreement with evidence than everyday life does.

Here’s an example of the differences between the two:

Suppose I say “it’s a fact that I always coffee with my breakfast”. What I am saying actually means that I have coffee with my breakfast far more often than not.

To be classed with the same level of precision as a scientific fact, I would have to be observed under strict conditions for a long period of time, over many, many mornings, before it would be accepted. If I failed to have coffee on even one morning, this would be enough to render the scientific fact as false and it would cease to be true, and from this it would be necessary to change the scientific explanation of my morning routine.

However, if I have coffee every morning for 10 years, and on one Sunday five years ago I had tea instead, I could still say that I have coffee every morning, and it would be, for want of a better word, a “fact” as far as everyday use goes, but it couldn’t be called a fact by science, as one cup of tea puts the lie to this.

The scientific definition of fact is, to some degree, also applied within certain aspects of the law. A lawyer questioning me on the stand about that day five years ago would, legitimately, question my claim to having coffee every morning.

As you can also see from the chart, a scientific theory comes after a scientific fact. Another word that comes into play when talking about scientific theories is “model”². This is because facts are simply records of what is; theories/models on the other hand are explanations as to why or how the facts are the way they are, and allow us (generally) to make predictions about what other sorts of things we would expect to see if the “facts” are indeed the case. Theories, and models, explain collections of evidence as facts.

As I started out with the notion of the rejection of evolution by those opining that “it’s only a theory”, I’ve included another graph below to demonstrate where creationism, ID and evolution rank against the scientific language.

Creationism is simply an acceptance of one idea (”a god did it”) as a truism, but it has no explanatory power whatsoever about how the god supposedly did it. This is because it’s decided by fiat in accordance with scriptures as decreed by the clergy, and has nothing to do with any kind of evidence with regards to the reality of our universe. Creationism isn’t even a guess, it’s just ignorance.

ID is subtly different from creationism, but not much. The idea behind ID is to attempt to detect so-called design within the universe, and then call this evidence of a designer (again, “a god did it”). Like creationism, it has no explanatory power of how a god did it, it just assumes that it did. However, ID isn’t even on par with a scientific hypothesis, in that it doesn’t propose any experiments to be able to test the proposed idea, nor how one should be able to identify “design”, nor who or what the designer is, nor how the designer is supposed to have designed whatever is the subject of investigation. It should be pointed out, though, that almost all supporters of ID are evolution-denying theists³.

In the case of evolution, we have the facts of it, provided by DNA evidence, observation of the commonality of life through the fossil record, and common descent with modification⁴, and the theory/model, originally based on Darwin’s theory of natural selection but since expanded, which explains how the recorded facts came to be.

Evolution is both a fact and a theory (model) explaining those facts. For somebody to say that it’s “just a theory” is just fallacious, and demonstrates that the claimant doesn’t understand what evolution is, nor how science works.

On a related note, this has got to be the most complete (and hence the dumbest) collection of anti-evolution disinformation ever, although I loved this note at the top:

Since Dr. Powell gives almost everything away he operates on a shoe-string budget. He has no funds to reprint with. Dr. Powell has been wanting to reprint his books, but no one has seen the need to help the last two years. If you would like to help print some of his books, you may contact him at: [removed] or E-mail at: [removed]. Presently, he does not have any funds to reprint and looks like never will unless someone asks God if they should help.⁵

I guess, Mr Powell’s god isn’t too interested in helping him distribute his writings itself. Who could have imagined that?

1. of course this diagram isn’t exhaustive, neither is it precise, and it takes a few liberties with regards to what consititutes “knowledge”. My primary purpose with this is to provide a platform for general comparisons only [↩]
2. which I’ve not included on this diagram [↩]
3. there are exceptions for groups like the raëlians, but these are not discussed here [↩]
4. why children are similar to, yet different from, their parents [↩]
5. I removed his details, but you can see them for yourself on his web site, if you so choose [↩]

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