I'd like to point out that this whole topic is philosophy. I'd also like to point out that science is the practical pursuit of knowledge about the natural world. Philosophy is the study of knowledge and so science and philosophy necessarily meet - even if scientists don't realise they are being philosophers, there is an enormous and necessary amount of it in science. Naturally there is a giant amount of philosophy that is little or nothing to do with science whatsoever, but this fact shouldn't be used to distract us from the idea that that within science there is plenty of philosophy to be getting to grips with.
When is a explanatory framework secure enough to be considered 'good science'? Does a theory have to be falsifiable in practice or only in principle? (Certain theories in physics might be unfalsifiable in practice since to try would require infinite energy or a device larger than the universe or some such thing, but the are certainly falsifiable in principle) and what about theories that cannot be falsified today, but it is feasible that one day we will have the technology or the means to falsify them?
How much induction is too much induction? Bertrand Russell sopke to this old problem, "the general principles of science . . . are believed because mankind have found innumerable instances of their truth and no instances of their falsehood. But this affords no evidence for their truth in the future, unless the inductive principle is assumed.". Is a theory an actual approximation of truth or just a pragmatic model? How closely should we stick to parsimony? When our observations contradict a theory, when do we assume our observations (or scientific instruments etc) are faulty and when do we throw the theory out?
As Dan Dennett once argued:
quote:
There is no such thing as philosophy-free science; there is only science whose philosophical baggage is taken on board without examination.
The general answer, incidentally, to most of the philosophical questions posed above is 'leave it up to the collective judgement of scientists'. Still, taking these kinds of issues for granted is exactly the kind of thing that leads to intellectual stagnation.
Is "There are a nine planets in the solar system" a theory or not? One could say that this fact, combined with the laws of motion and gravity explain some of what we see in the night sky, and it is falsifiable (just like when the theory was "There are seven planets..." and we'll leave aside definitional issues like with Pluto) - but then it is hardly the kind of general theory that Relativity or the Modern Synthesis Theory of Evolution or what have you.
There were some good posts early on that covered a lot of what I was going to say so I'll draw to a close here. The important thing is that what a theory is dependant on context, and not just whether it is scientific or not. Still, even straight forward simplifications of these issues is difficult enough to hammer into the brain (or gently slide depending on preference) of the typical evolution denying poster around here. It would be a travesty if every time someone turned up with some definitely wrong idea of what the word theory means
in the context it is being used we had to devolve into complex philosophical and linguistic discussions (though the occasional thread is good fun and educational for all, of course).