Just A Theory

Iain Murray, in his comment on the fact that the Supremes are not going to review the latest “teaching evolution” case, says:

…the idea that “evolution is just a theory” is quite simply wrong. The fact of evolution has been established beyond reasonable doubt. It is how evolution works that is in question. From this report, it appears that the science teacher questions even the fact.

While I think that I know what he means, this isn’t really the case. Evolution is (in fact) a theory, though it’s not “just” a theory. To say something is “just” a theory is to denigrate the very notion of theories, which are part of the fundamental basis of the scientific method.

Evolution is “just” a theory. As are Newton’s Laws. As are both Special and General Relativity. As are all scientific principles.

We cannot prove any of them to be correct–theories can only be falsified. What we can do is lay out a set of criteria by which we judge the validity of scientific theories, and determine to what degree they are satisfied by particular theories. Those that satisfy the criteria best become the most accepted theories. Evolution, in broad terms (though the details are still problematic), does provide the current best available explanation for the diversity of life and the fossil record, within the confines of science.

These last words are key. The problem with teaching creationism as a substitute for evolution is not that it isn’t true–there’s no way to know that. It’s that it isn’t science. In a science class, what should be taught is science and the scientific method. Whether or not this represents the “truth,” or the most reliable means of achieving knowledge is unknown, unknowable, and irrelevant.

The scientific method and logic are the means chosen by people of reason to gain knowledge, at least in those spheres for which such means are applicable. The acceptance of them, like the acceptance of Biblical or other forms of divine revelation, must ultimately be taken on faith. This is disconcerting to scientists, but it’s true nonetheless.

Articles of faith for those of reason (like myself) are:

  • There is an objective reality
  • This reality is not affected simply by the beliefs of others
  • Its nature can be determined, ultimately, by forming falsifiable theories about it, and asking questions of it in the form of experiments

There may be others, but these are clearly axioms of the scientific-minded, and they cannot be proven, even to someone who accepts logic and proofs as a means of achieving knowledge. For those whose chosen method of gaining knowlege is divine revelation, there is no effective argument.

So there is some truth to the claims of the devout that “secular humanism” is a religion, which to me, merely means that if we don’t want to indoctrinate children in public schools, there is no solution except to abolish public schools (perhaps replacing them with vouchers, if we believe that education should be publicly funded), because “everyone’s gotta believe in somethin’.”


After an email exchange with Iain, he puts the following on his web site, from another website:

Just as much as gravitation is a fact, is so evolution.

I agree that evolution is as much of a fact as gravitation. The problem, is, as I state above, that neither is a “fact.” Gravitation is a theory. I fear that this website is obscuring terminology in an attempt to convey a (valid) concept–that evolution is as well-founded as any other scientific theory. Such sloppiness does nothing to advance the cause of science in general, or evolution in particular.

Here is an example.

Fact: When I drop an object, it falls toward the center of the earth with an acceleration of approximately 32 feet per second per second.

Theory: This happens because two masses attract each other in proportion to their product, and in inverse proportion to the square of the distance between them.

The second is what we call “gravitation.” The first is a fact, but it’s not gravitation–it’s simply a phenomenon that we explain with gravitation (and which could be explained with other theories, but not as well, by scientific criteria).

Similarly, the available fossil record and existing inventory of flora and fauna is a fact (or to be more precise, a compendium of facts). That they evolved into the present state via natural selection is a theory that explains those facts.

Really, folks, there’s nothing wrong with theories. Despite the attempt of creationists to use them to damn evolution, they are the stuff that all science is made of.