A common tactic used by creationists to slough off the Theory of Evolution is to say 'Well, it's just a theory'. There are two basic misunderstood priniciples here. The first is that the word Theory (the capitalization is intentional here) means something much different in science than in its colloquial usage. A Theory, unlike a theory in the layman small-'t' sense, has to have the following properties:
- it fully and satisfactorily explains a set of observations;
- it does not invoke the supernatural;
- it is falsifiable, meaning that it can be shown to be incorrect;
- makes predictions which can be verified.
A Theory is something that has survived an onslaught of slings and arrows against it, making it as close to a factual explanation as any scientist is willing to admit to. Saying that the Theory of Evolution is 'just a theory' is like saying the Theory of Gravity is 'just a theory', yet here we are bound to the earth without the need for extraordinary measures to remain in contact with the surface of the Earth.
Few theories make it to the grand title of Theory, and are amongst the greatest achievments of humankind. Quantum Theory, the Theory of Relativity, the whimsically-named Big Bang Theory and yes, the Theory of Evolution are some of the greatest pieces of scientific detective work of all time.
The second misunderstanding concerns the more understandably confusing use of the word 'evolution'. Darwin did not invent evolution. Nature did. It was known long before Darwin's opus that life evolved, but its mechanism was not understood. Earlier hypotheses, such as Lamarckian evolution, failed to adequately explain how evolution occurs. And it does occur, just as gravity exists. Whether or not we explain it (or believe it happens) is irrelevant. It just is. What Darwin surmised (and independently Wallace) is that evolution (the fact) occurs through natural selection (the explanation). It is unfortunate that the term 'natural selection' is used synonymously with 'evolution'. The Theory of Evolution should thus really be called the Theory of Natural Selection to avoid confusion. Our bad. Consider the mistake corrected, and I never want to hear inanities such as "it's just a theory" ever again. To use 'it's just a theory' to decry natural selection or evolution as mere guesswork is false, disingenuous and just plain ignorant. Period.
One thing you might be wondering is why the invokation of god not allowed? The answer is quite simple: It's too easy. It is the laziest thing you can do in Science. If you invoke it in one place, why not everywhere? What religion does is take away the need to look for a real answer. Richard Dawkins is less than charitable about this. I'm even less so. Why look for a real explanation for the diversity of life when you can just attribute it to a god? The ultimate in 'Easy' buttons. Wow, isn't god great?
Religion is a pathetic attempt at explaining the world around us. It has robbed humankind of centuries of amazing accomplishments that we could already be marvelling at. As Richard Lederer put it, "There once was a time when all people believed in God and the church ruled. This time was called the Dark Ages." It is entirely possible that without religion humans would have developed the computer, visited the moon and cured most forms of cancer all before 1000 A.D. What kind of age would we be living in with that alternate reality?
I feel cheated and so should you.