What is a theory?

Now before I get onto talking about and defining the other side of this argument, I'd like to talk a bit about theories. Often it's said by creationists and those who support intelligent design that they "do not believe in the theory of evolution". Now I have two problems with a statement like that, and I want to explain them a bit and why it's pretty much wrong.


The first problem is using the word theory. The use of theory in this way (or in the context in which it is used) really seems to belittle the scientific meaning of the term. A theory isn't a wishy washy guess that is agreed on by a few people, it is an idea that has been thoroughly debated, is highly supported by evidence that explains most or all observations, and can make predictions about future observations. Even beyond this misconception though, the bigger problem is that evolution isn't really considered to be a theory any more by science. It has been so widely observed, and so widely agreed on, that it's considered to be a fact now. A fact in science is when a theory is considered to be so correct, and with so little remaining doubt, that there seems no reason left to continue testing. It's the same as saying that the Earth revolves around the Sun is simply a fact. I also think this applies to natural selection in its most basic form (if you don't take it as the mechanism for developing new species). A faster cheetah will get its dinner more often than a slower one or a tree that grows taller will get more sunlight, and it's these organisms that will go on to reproduce over the other, weaker, ones.


My other problem with this statement is the word believe... But I guess that's just me being fussy. It's probably no different to someone saying 'I don't believe in aliens'. There is 'evidence' for both aliens and evolution (although one is concrete and the other is sketchy (not respectively)). What people really should say is something like 'I don't believe the evidence for aliens correlates to that conclusion'... or something along those lines, but perhaps less wordy.