In comments over at my PJM piece today, I find this:

I agreed with Rand’s article, except for this point:

“But every scientist worthy of the name should be a skeptic. Every theory should be subject to challenge on a scientific basis.”

It is true that every “theory” should be regarded skeptically if there is *cause* to do so (ie evidence for doubt). But not every idea about reality is still a theory. For instance, it is no longer a “theory” that the earth is round (rather than flat). That fact has now been established. The idea is no longer a theory, but is true. There is no basis for being skeptical – for doubting – this conclusion.

The question which gets ignored here is at what point does a theory become a truth? At what point does a conclusion go from being possible, to probable, to certain?

To suggest scientists must -always- be skeptical is to claim that certainty can never be reached – about anything. That is simply a false statement. That is not science. That is the acceptance and practice of a particular philosophy – Skepticism – which is something -quite- different from reason.

The actual problem here is that many people are treating an idea which is (at best) a flawed *hypothesis* as if it were not just a theory but an actual certainty – ie as if they somehow know it to be true. In other words, they hold their conclusion not based on the methodology of reason, but by means of faith.

I think there are some nomenclature issues here. There was a time that the notion that the earth was round (or flat) was a theory. There was no direct evidence either way. That is no longer the case not because the “round-earth” theory has been somehow refined, but because we have actually been able to see pictures of a round planet, from various angles. That the earth is round is a fact, not a theory (one of the reasons that Flat-Earth societies are a literal joke). Gravity, however, remains a theory that explains the physical behavior of every object in the universe (as far as we know). It will never become a fact. It will never be more than the best explanation, and something (in theory…) better could still come along. The same thing applies to evolution, which is the best theory (currently) that explains the facts (the fossil record and DNA relationships). Intelligent design is not a theory — it is a critique of a theory (evolution). But one doesn’t have to propose a better theory in order to shoot one down. If the climate data has been tampered with, it makes their theory suspect, regardless of any alternatives that the critics may have.