Why won't this argument just go away? It reflects badly on the person who uses it. It just demonstrates that they are ignorant of science and the scientific use of the word theory. It only gets them brownie points among people who are ignorant of science. Even
Answers in Genesis is getting on the bandwagon on this.
Colloquially a theory is at best an educated guess. In science this would roughly be equivalent a hypothesis. A theory is an explanation for a phenomenon. Sometimes hypotheses can accumulate enough evidence to become theories. Theories must be supported by facts.
Examples of theories are: evolution, big bang, gravity, heliocentrism (solar system), atomic theory of matter, and the germ theory of disease. All of these are rock solid principles of science with lots of evidence behind them.
WE NEED TO RETIRE THIS ARGUMENT!!!
I would use the word 'hypothesis' when I mean 'hypothesis'.
'theory' is a much stronger term than 'hypothesis'.
The following is a quick writing job, and I'll probably want to change some wording later, but it is close to how I think about things...
In terms of our confidence in a statement, the following ordering holds:
'hypothesis' < 'conjecture' < 'theorem' = 'theory' < 'law'
The following are not proper definitions, but are how I use these words:
An
hypothesis is simply a statement - little or no expectation of the validity of the statement is being suggested.
A
conjecture is a statement that is thought likely to be true, at least by its conjecturer, but that has not been proven to be true (e.g. Goldbach's Conjecture).
A
theorem is a statement that has been proven by deriving it from a set of axioms by the appropriate application of a set of rules of inference. The theorem is true under every interpretation for which the axioms are true. The theorem is only as good as the axioms.
Fermat's Last Theorem was really a conjecture until a few years ago, but was called a 'theorem' out of respect for Fermat and his conjecturing skills. Once it was proven, it became a proper theorem.
A
theory is a mathematical system that is defined by a set of axioms. I like to think of this as the 'shadow' cast by the set of axioms, and regard a theory as generating all of the consequences of the set of axioms, or as that set of consequences itself. The theory is only as good as the axioms.
I'll say that a theory (viewed as a set of consequences of the axioms) is true under every interpretation for which the axioms are true.
We talk about evolution being a theory. What we mean by this is that it is a coherent system of thought that we believe could, with a great deal of work and new understanding, be systematized, formalized, and axiomized. By calling evolution a theory, we express our expectation that the system is valid under some (realistic) interpretations and our expectation that formalization of the system will be achievable at some point in the future. Furthermore, we generally have enough evidence for evolution to regard many of its theorems as laws.
We tend to use the word 'law' in science, or in areas of mathematics which we expect to conform to or to approximate reality.
I'll say that a
law is a theorem that is true under precisely those interpretations that conform to our understanding of reality.
That's my first cut in examining those words in the context of logic.
- but ironically, this public outing of his dishonesty HAD NO EFFECT on the people who were there supporting him! Talk about brainwashing 
