I very much agree with that quote.

Let me explain how I, as an astrophysicist, see the scientific process, what the word "theory" means to me and give some examples.

I think the scientific use of the word "theory" is yet another example of the scientific meaning of a word being much more specific than the general everyday meaning of a word. When I say "theory" I mean a model to describe how something works. That model must be checked against experimental/observational evidence. There is a symbiosis between "theory" and "experiment." As we gather more evidence, support for a model either grows, or if the evidence is inconsistent with the model, we refine the model, or make a knew one. The growth of a model is fairly organic in that sense. It can grow tender new branches and leaves on the forefront of scientific inquiry. Many of those will be knocked down with new evidence, some will grow from new evidence. Eventually the evidence will be so strong, that it is hard to refute, something we would call a "fact." For example, saying that the Earth is round is a "model", or "theory" which now has some pretty convincing evidence, so we call it a "fact."

That the universe is expanding has very strong experimental evidence. The fact that people argue the *value* of the rate to 50% (and I'm being generous on the uncertainty there) does not change the fact that all evidence points towards expansion.
This is just to warn against confusing arguments over the details for arguments whether the general framework (trunk of the tree) is correct.

Even if a scientist pulls a "theory" out of thin air, it must be tested with experimental/observational evidence.
Models will also predict things we have not yet observed, so observers can plan their experiments to test if the predictions from the models are correct.

Finally, I'm not a biologist, but maybe someone could present the evidence for/against evolution. I can think of some things in favor: the fossil record, watching generations of fruit flies evolve before our very eyes, etc. The social consequences of how people use evolution is not evidence against whether it is true or not. Show me data. Also, if you have a competing theory of the origin of the species, please present quantitative evidence for and against that, as well as the method by which the evidence was gathered.

Kim

> "It is neither possible nor necessary for the general public to
> have detailed scientific knowledge across a range of disciplines. Instead,
> what is important is scientific awareness - an understanding of what the
> scientific enterprise is about, what a scientist means by the word 'theory,'
> and what it means to establish a 'scientific fact.' For instance, many
> people say 'evolution is just a theory,' assuming this means its basic
> principles are still debatable. They do not realize that gravity is also
> 'just a theory,' and that, to a scientist, a theory is an explanation of
> what has been observed._
>
> - Keith Devlin (American Journal of Physics, July 1998, p. 559)