# Word of the Day: Theory and Law

Let’s start with a few definitions within mathematics and logic.  An axiom or postulate is a proposition (statement) taken as a given.  A lemma is an intermediate proposition or stepping stone rather than the final result, which is a theorem.  A corollary follows readily from a theorem—it’s often simply another way of stating the theorem.  Lemmas, theorems, and corollaries are all proven, but proofs are only possible within mathematics and logic, not within science.

By contrast, all scientific statements are provisional.  A scientific hypothesis is a testable explanation for a phenomenon.  It explains and predicts.  Once a hypothesis has proven itself, it becomes a scientific theory.  A scientific law is a description of a natural phenomenon, often an equation.  Laws and theories are both well-tested, widely or universally accepted within the field, and falsifiable.  The main difference is that a theory explains while a law describes.

For example, germ theory, quantum theory, and the theory of evolution are explanations.  Boyle’s law, Ohm’s law, and Newton’s law of gravity are all descriptions (and are all equations).

A common misconception is that scientific hypotheses mature to theories, which mature to facts or laws.  Instead, facts (the observations from an experiment, for example) lead to hypotheses (a plausible but immature explanation), which lead to theories (well-evidenced explanations).  In the category of scientific explanations, a theory is as good as it gets and it doesn’t graduate to become a law.

Photo credit: Marvin (PA)

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# Bungling the Facts Behind Evolution

A Huffington Post article earlier this week asked, “Does Questioning Evolution Make You Anti-Science?

Yeah, pretty much.

The author notes the flak Rick Perry received for stating that evolution was “just a theory” and that it has “some gaps in it” and tried to make the case that Republicans aren’t as anti-science as they’re portrayed.  I’m not interested in the politics here, but the science (or failure to understand science) is worth mentioning.

Denial of both climate change and evolution is popular among conservatives.  The author said, “While I cannot comment on climate-change science, I do have a great deal to say about evolution.”  He lists his credentials as organizing an annual science vs. religion debate at Oxford University, which were typically about evolution, and giving Richard Dawkins a good thrashing at another debate for good measure.

But for someone who’s well versed in these matters, his understanding of science seems stunted.

What I learned from these debates, as well as reading extensively on evolution, is that evolutionists have a tough time defending the theory when challenged in open dialogue.

I doubt that, but let’s assume it’s the case.  Who cares?  Science, not debate, is where our confidence in evolution comes from.

[Attacks on evolution do not] mean that evolution is not true or that theory is without merit or evidence. It does, however, corroborate what Governor Perry said.  Evolution is a theory.  Unlike, say, the laws of thermodynamics, it has never been proven beyond the shadow of a doubt to be true.

Wow—where do you start?

Evolution is an explanation.  It claims to give us the mechanism explaining how life got to be the way it is.  The best evolution can hope for is to become a theory, and it has done so.  The same is true for germ theory, another explanation, which has also reached that pinnacle and can’t become anything better.

By contrast, a scientific law is Continue reading