(Spoiler alert: no.)
One of the criticisms most often levelled at the theory of evolution is that it’s “just a theory”. The clue’s in the name, after all. So if we’re not really all that sure about it, some people tell us, we ought to at least consider some alternative ideas. If it’s “just a theory”, then it’s apparently not yet a fact, and so to insist that no other explanations should even be considered is unfair to other worldviews, most notably Creationism (and/or Intelligent Design).
There’s a number of things wrong with this.
Let me clarify, though, that my problem isn’t with the labelling of evolution as a “theory”. It may be the case that scientists aren’t always the most effective people to do their own PR work, but their image problem isn’t so hopeless that such a common phrase as “the theory of evolution” isn’t even accurate. It is a theory.
My problems – two of them, I suppose – are about the word “just”.
First of all, saying that evolution is “just” a theory is kinda like saying the United States “only” won thirty-six gold medals at the 2008 Beijing Olympics, or that Sylvia Browne has given “hardly any” desperate parents utterly false information about the whereabouts of their missing children. However much you try and play it down, it’s still quite a lot.
A scientific idea about how stuff works doesn’t get to be a theory the moment someone stands up on a box on a street corner and starts shouting about it, or even the minute they get a paper about it published in a respected journal. A theory is a complete model, which describes a phenomenon, and which has stood up to testing against actual data. It’s a word that’s casually tossed around a lot out in the rest of the world, but in science, theories are tough sons of bitches that have gone through the mill. It’s not a term that denigrates anything; if anything, it’s quite a badge of honour. (I’ve written more about the scientific method before.)
My other problem with this statement is that it’s not even true. Evolution isn’t just a theory. Gould had a great line about this:
Evolution is a theory. It is also a fact. And facts and theories are different things, not rungs in a hierarchy of increasing certainty.
This is to do with those pesky differences between how scientists use words, and how they’re more commonly understood. (What’s with scientists thinking they can just use words to mean what they want them to mean, anyway? Next they’ll be telling us a parsec isn’t really a measurement of time, or something.)
Colloquially, if you’ve no idea of the answer to something, you might take a guess. If you’re got a bit of an idea, and are trying to impress someone who’s easily impressed by slightly long words, you could have a hypothesis. Pretty much interchangeably with that, you may instead come up with a theory. If you’re more sure you know what’s going on, you might make an assertion, or an allegation. And something that’s not even up for discussion any more, because nobody has any doubt about what’s really true, is a fact.
But in a scientific context, these terms don’t line up in a hierarchy of increasing certainty like that, any more than an apple is more definitely a fruit than a strawberry, which itself is better than a pear. A theory is a good thing to have, a model for explaining stuff; it doesn’t mean you’ve still got a way to go before you’ve “proved” anything. Facts are useful, and can be gathered out in the real world as data is observed, but facts are things that need to be explained, and predicted, by some overall vision of what’s going on, and an understanding of what they mean. That’s what a theory is for.
One of Wikipedia’s pages on evolution has a lot more on this, and some quite gripping drama on the discussion page, too.