After pondering the adefinitemaybe case for a bit, I can't shake the feeling that we really screwed this one up in a systematic way, that Less Wrong's structure might be turning potential contributors off (or turning them into trolls). I have a few ideas for fixes, and I'll post them as replies to this comment.

Essentially, what it looks like to me is that adefmay checked out a few recent articles, was intrigued, and posted something they thought clever and provocative (as well as true). Now, there were two problems with adefmay's comment: first, they had an idea of the meaning of "evidence" that rules out almost everything short of a mathematical proof, and secondly, the comment looked like something that a troll could have written in bad faith.

But what happened next is crucial, it seems to me. A bunch of us downvoted the comment or (including me) wrote replies that look pretty dismissive and brusque. Thus adefmay immediately felt attacked from all sides, with nobody forming a substantive and calm reply (at best, we sent links to pages whose relevance was clear to us but not to adefmay). Is it any wonder that they weren't willing to reconsider their definition of evidence, and that they started relishing their assigned role?

It might be too late now to salvage this particular situation, but the general problem needs to be addressed. When somebody with rationalist potential first signs up for an account, I think the chances of this situation recurring are way too high if they just jump right into a current thread as seems natural, because we seem like people who talk in special jargon and dismiss the obvious counterarguments for obscure reasons. It's not clear from the outset that there are good reasons for the things we take for granted, or that we're answering in shorthand because the Big Idea the new person just presented is fully answered within an old argument we've had.