Pullings "facts" out of the air

[Aorus]

A couple of my friends seem to have a penchant for pulling "facts" out of the air in discussions on various topics. The problem is that I often think their statements are dubious or overgeneralized but sometimes I simply don't have enough knowledge on whatever we're discussing to counter them effectively.

I think I'm reasonably well informed in a lot of areas, moreso than they are, and trying to inform myself even more than I already do isn't really feasible.

This isn't a huge issue for me on this level, but it does become important in debates because people can "win" arguments based on bullshit if their opponent has no effective rebuttal. I take it there isn't really any legitimate and effective way of countering this without actually further researching the topic. Your thoughts?

[Darth Wong]

I would suggest a simple question: "Exactly where did you get that fact? I'd like to look it up myself." Especially if that fact seems surprising or contentious.

If the person hems and haws or gives you a vague response, it tends to seriously damage his credibility. Especially if he has no particular personal qualifications which would suggest that he is an expert in such matters.

[Junghalli]

I second that. The way to deal with somebody pulling facts out of the air is to ask them to prove it.