Sunday, July 26, 2009

'Theory' and 'Hypothesis' in Science, and in the Creationism Debate
Is Evolution "Just" a Theory?

Here's one of those things I've been meaning to comment on for years, but have never gotten around to. Biologists have recently gained a rhetorical advantage in the creationism debate by claiming the following:
A theory is a hypothesis that is fairly well-confirmed.
Why is this important? Because of the well-known creationist claim that:
Evolution is just a theory.
In response to this vexing bumper-sticker of a slogan, many now invoke the above neologistic definition of 'theory,' and respond:
No--to say that evolution is a theory is (by definition) to say that it is fairly well-confirmed. You mistakenly think that to call it a theory is to say that it is largely speculative.
It's amazing how well this shenanigan works.

But it's B.S.

'T is a theory' does not entail that T is fairly well-confirmed, and, as Carroll notes, even scientists don't use the term that way. In fact, there's no hard-and-fast line between being a theory and being a hypothesis. To the extent that there's any standardization here, it goes something like this: theories tend to be bigger than hypotheses. They tend to be systems of hypotheses, as opposed to single explanatory conclusions. But a hypothesis is a limiting case of a theory. If I hear a loud noise and conjecture that something blew up, then I can rightly say that I have a hypothesis, or I can rightly say that I have a theory. The imaginary definition of 'theory' above was apparently introduced specifically to trip up creationists.

Who--don't get me wrong--deserve to be tripped up. They routinely employ shenanigans way more reprehensible than this one, and we can hardly blame the scientists for firing back in kind every now and then.

But the correct answer to the "it's just a theory" assertion goes like this:
No, it's an extremely well-confirmed theory.
There are theories and theories. Some are well-confirmed, some are not. Evolution is one of the former (not that I think it has achieved its final form, for I do not.) To harp on the fact that it's a theory ("just" a theory) is to exploit the fact that, colloquially, to call T a theory is to assert that it is ipso facto particularly uncertain or in doubt. But that's not really how scientists use the term, either. They do like to keep their fallibilism front and center, so they do like to continue referring to things as theories far past the point at which most folk would have begun to refer to them as facts. (Though I did have a particularly dogmatic biology prof who insisted that everyone refer to evolution as "the fact of evolution." So that's another strategy, I guess...) But this doesn't change the fact that some theories are near certainties. Some theories are theories that are well-confirmed, and therefore (sometimes extremely) likely to be true at least in their broad outlines--and evolution is one of them.

This case really fascinates me because it caught my attention as soon as the "all theories are well-confirmed" meme began to circulate. I knew it was erroneous, of course, but was surprised at how effective it seemed to be. It's wrong, but it does the same job that the truth would do, and apparently does it better. So, I thought, why harp on the facts if they're just gonig to cause trouble for the good guys?

Well, I'm never happy about such compromises, and since Carroll has broached the subject, I suppose I might as well say my piece. So there it is.


Anonymous Lewis Carroll said...


Since I'm a little skeptical of the theory of gravity, I'm developing my own personal theory of 'intelligent falling'.

Go ahead and prove it's NOT TRUE.

10:19 PM  
Anonymous The Dark Avenger said...

Unfortunately, LC, someone has beaten you to the punch:

"Things fall not because they are acted upon by some gravitational force, but because a higher intelligence, 'God' if you will, is pushing them down," said Gabriel Burdett, who holds degrees in education, applied Scripture, and physics from Oral Roberts University.

1:25 AM  
Anonymous Lewis Carroll said...

Uh, um... wow, I guess is all I can say.

10:29 PM  
Blogger Spencer said...

I don't know what's more alarming: that this guy has a physics degree or that he has an education degree.

9:56 PM  
Blogger Spencer said...

New Onion headline: "Area Man Fails to Follow Link Before Commenting"

9:58 PM  

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