Well in my experience that assumption often holds - most people aren't rational, don't understand the issues and will proceed to try and beat you down with "talking points".

I have a two part test to figure out whether someone's a skeptic or a denier:

1. Ask them some sort of question about their position - "Why do you think X", or "How do you explain this weakpoint in your argument?" Basically try and put them on the spot a bit.

2. If they're evasive, then ask them what sort of evidence it would take for them to change their mind.

If they can't give a good response to either of these questions, then they're a denier - if you can't defend your position, and you're not going to admit to any possibility of error, there's not much point in arguing.

It does often hold, but to me this doesn't justify the arrogance I see so often today. If we spoke with more honest language it might head off some of the defensive responses and make it easier to pinpoint the real break downs in communication. For example, for me the problem isn't that people aren't convinced by the GW evidence accumulated so far (either side). The problem is they are actively advocating a theory based on ignorance (e.g. "it's not conclusive that the cause is X so therefor I assert it is Y").

Sure, but just because something isn't completely conclusive, doesn't mean that it's wrong, or that you shouldn't start taking action based on it. And where do you draw the line? If something's 99% certain, or 99.9% certain, at what point do you stop arguing and take it as fact? When are you allowed to start actively advocating a particular theory?

>or that you shouldn't start taking action based on it.

Those who are convinced should indeed start taking action.

>And where do you draw the line?

That's up to the person. Some people have a threshold so high it will always be beyond our grasp to meet, some have a threshold of "higher probability score than any alternative" no matter how low the probability actually is (e.g. 5% chance vs 2%, 1%, etc.).

>at what point do you stop arguing and take it as fact?

Again, it's up to the person. But again, if the person doesn't accept something as fact I'm fine with that. I'm not fine with them presenting their unconvinced-ness as some kind of alternative "theory".

>When are you allowed to start actively advocating a particular theory?

When you have one. "The other guy is probably wrong" isn't a theory.