Nature of Science

I had a devil of a time finding this information today using typical search terms, so I thought I would post it here. I searched for: NAS definition of fact law hypothesis theory: and nothing ever led me directly to what I wanted. I had to go through several layers and follow some links and ultimately I just stumbled on the right page.

I think it's important for science teachers to be consistent in the use of terminology, especially in today's world where a war of rhetoric is being waged against science and where the common everyday conception of terms like law, theory, and hypothesis provides a source of confusion that opponents of science like to exploit.

So here is the National Academy of Sciences' definitions of fact, law, hypothesis, theory:

Glossary of Terms Used in Teaching About the Nature of Science

Fact: In science, an observation that has been repeatedly confirmed.

Law: A descriptive generalization about how some aspect of the natural world behaves under stated circumstances.

Hypothesis: A testable statement about the natural world that can be used to build more complex inferences and explanations.

Theory: In science, a well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses.

These definitions often conflict with the definitions presented in H.S. textbooks, but I don't recommend using H.S. textbooks to find authoritative answers to science questions. I also think that it makes sense to distinguish between established theories and proposed theories that are sometimes in conflict with established theories. I think the main point is that theories are explanations of how some aspect of nature works, and not just descriptions of nature. They are also the end of the road in a sense. Theories are the ultimate goal of science, and not a pit stop on the way to some other concept like "laws" or "facts."

A final point. It always bears repeating that evolution is an established theory and that there is no other theory* out there to explain the progression of life on earth over time. No one has even proposed an alternative theory to evolution. Can anyone even imagine a serious alternative to evolution? It is that well established.

*Creationism is not a theory. Creation "science" is not a theory. ID is not a theory.