An article at Wired by Clive Thompson notes that the antievolutionists use rhetorical ploys, playing on the ambiguity of language to imply that "theory" just means "wild-arsed guess" (or words to that effect). He proposes that we should stop calling evolution a theory, and start calling it a "law".
I disagree:
The term "theory" has much wider application than "law", and in any event, the very same sorts of rhetorical ambiguity will be used for that too (a law requires a lawmaker, doesn't it? Hmm? So evolution is false, blah, blah, blah). In fact, "law" is the term that should be, and largely has been, retired from science, outside of physics, anyway.
It used to be that when any generalisation in a science was proposed, it got called a law, and this happened in biology too, including evolutionary biology. Cope's Law, Dollo's Law, Gompertz' Law, Haldane's Rule, the Law of Ancestral Heredity, the list goes on. And all of them lack one crucial aspect of a law of science - they are not exceptionless.
Well, neither are some classical laws in physics, such as the ideal gas law, but the basic idea is that a law has to be without exception in the explanatory domain in which it is expected to operate. And evolution is not such a law. Taxa can remain static or change, they can adapt or suffer contingency, they can get bigger, smaller, and so on. There are some rigorous mathematical models for each of these, but they do not qualify as laws simply because the implementation of each model requires non-universal boundary conditions. In short, you cannot assume that the conditions that make one model apply in one case will make it apply in some other case.
"Theory", on the other hand, deals nicely with this. Theories, as I have said before, contain models of various kinds, generalisations that do not need to act without exception, interpretations for specific cases, and so on. They are not simple minded laws of any kind. Perhaps in physics this line runs better than it does in biology - certainly biology is more particularistic than physics, which is expected to work everywhere in much the same manner. Biology is something that works only when things are what they are - a species of ant is going to have a very different set of conditions to a species of hedgehog or algae or lichen or...
So while I appreciate Mr Thompson's intention, I think he is making a basic mistake. No amount of retreat will ever satisfy the cravings of antievolutionists or prevent them from sowing confusion. Better to teach more people what it is that a theory does. I think at the very least we should unleash hordes of philosophers of science into the education system and media...
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Comments
Anarchist Bob
Posted by: Bob O'H | October 23, 2007 11:32 AM
Evolution is not a law for the same reason Newtonian mechanics isn't a law: laws are simple. It's totally a category error to speak of evolution as a law.
Posted by: brtkrbzhnv | October 23, 2007 11:55 AM
If it is technically incorrect and causes confusion, should every "generalisation in a science" we currently call a law get renamed?
It could happen. Look at how Pluto got reclassified from being a planet to being a mere dwarf planet. I think that change was hard as most people know what Pluto is and there was a great deal of media pressure on the matter. Outside of biologists, who has ever heard of Cope, Dollo or Gompertz?
I hope your Philophers of Science Hordes works better than the Mongolian Hordes technique.
Posted by: Todd Sayre | October 23, 2007 12:27 PM
To me we speak of laws in physics but not in biology because physics is much simpler. Laws are simple statements about the universe expressed in mathematical form. Biology is generally not simple enough to formulate such things.
Posted by: Dave S. | October 23, 2007 12:30 PM
Evolution is something that happens. Laws and theories are descriptions or explanations about things that happen.
The theory of evolution - that's a theory about evolution, and the theory of evolution is not evolution. Just like a theory of the earth is a theory about the earth - but the earth is not a theory (or a law). Just like the theory of flight is a theory, but flight is something that happens.
I have less objection to saying that evolution is a fact, but I'd prefer just to say that evolution is something that happens. If a one-word description is needed, perhaps evolution is a reality.
Posted by: TomS | October 23, 2007 12:52 PM
Dr. Wilkins wrote:
I agree completely with John here. This is, in part, what the Creationists and IDers want, a retreat that can give substance to such spurious claims as "teach the controversy". If we were to do this, then the response of Creationists would be "You see, the evolutionists know the weakness of a theory, and now they're playing a language trick."
There's no point in fighting these sorts of things at their level, and we're stuck with enough antiquated references to "Laws" as it is, which is a usage long discarded by the scientific community, without muddying the waters when we have a perfectly reasonable modern term, and all that it entails; "scientific theory".
Posted by: Aaron Clausen | October 23, 2007 3:51 PM
The misuse of "theory" to imply the common usage "wild hunch" applied the science is pretty unfortunate, as it implies a very high degree of uncertainty. But your basic point that they will always find something to nitpick about is correct -no amount of genuflecting is going to satisfy these people. Its the same situation when we have a statisical proof of something that is only 99.999%, the denialist will still tout that there is uncertainty, and the scientist usually goes back to his lab for a year to add yet one more nine. But the denialist's response is unchanged. Some people will never accept reality no matter how good your argument is.
Posted by: bigTom | October 23, 2007 6:16 PM
Forgive me for the temerity, but I must take issue with the philosopher of science on the question of evolution as theory or evolution as law. As I understand it, it is neither. My little formulation follows. . .
Evolution is a fact.
Natural selection is a fact.
That evolution occurs by natural selection (ENS) has and will be observed in individual cases is a fact, and it is known that speciation is one possible consequence of this being true.
What is theoretical is the relationship between evolution and natural selection in cases that can't be directly observed, and what this implies about the origin of species, common descent, etc. And, of course, theories are robust things, not mere hypotheses.
Posted by: Scott Hatfield, OM | October 25, 2007 3:45 AM
The fact of evolution is something described, modelled, and explained by the theory. But we do not have direct observational access to the fact of evolution outside the narrow horizon of human existence and scientific record. So either way there remains the theory, and it is that which is at issue.
Posted by: John S. Wilkins | October 25, 2007 4:45 AM
I prefer to be careful about using "of" appositively, and distinguishing it from the objective use. In other words, "facts of evolution" (note the plural) are facts about evolution, and "theories of evolution" are theories about evolution (the objective "of"), and not equation of evolution with facts or theories (which would be an appositive). ("The city of Leningrad" exemplifies an appositive "of". "The siege of Leningrad" - an objective "of".)
Among the facts about evolution is the fact that evolution happens wherever and wherever there is life: every time we are in a situation where we are able to observe evolution, we do observe it happening.
Posted by: TomS | October 25, 2007 7:58 AM
Posted by: Aa No Bhadrah | November 16, 2007 1:02 PM