"But So-and-so wouldn't lie to me!"

[Mesozoic Mister Nigel]

One method of teaching something to someone is to let them them persist in their folly until they encounter their error firsthand. Agree with them, take them by the hand and have them skip beside you down the path of their own flawed logic, and smile as that path leads them into the scary forest of error and doubt, and then point out how dark everything is all the sudden, how pointy and menacing the trees look, and whether or not those are eyes watching us from the bushes, all the while smiling. take them further down the path than they've ever thought to go. Then laugh maniacally as they quit the path to go sprinting towards reason.

In practice it's a bit like resorting to reductio ad absurdum, only you don't take it to a ridiculous extreme, jsut to the point where the flaws in their case become unavoidably obvious.

not-the-exact-one-i-wanted-yet-still-relevant link:https://www.youtube.com/watch?feature=player_embedded&v=WUXodFgbDfQ

This has proven the most effective method for me so far

the socratic approach!  I did that with my highschool students when i was tutoring, works for maths-related subjects but i never got it to work on anything else. maybe i have issues with applying logic to reality.

you just gotta push a little further, if you can't get their apparently flawed hypothesis to breaking point then maybe it is your own assumptions you should be questioning

WISA1 IS HERE TO TELL EVERYONE THEY'RE DOIN' IT WRONG.  SO EVERYONE PAY ATTENTION.

actually don't I'm just another drunk asshole who thinks he's right

Change your avatar right fucking now, or you're out on your ass.  You have 5 minutes from the date/time stamp of this post.

What did he have up?

Blatant pussy shot.  Like off of Redtube.

We only have 6 rules, FFS.  How hard is it?

Had to have been angling to get banned, that wouldn't fly anywhere. Maybe he thought he'd just get suspended or something.

Or was just drunk and an idiot.

I didn't like him, so it's no real loss, but it kind of sucks because at least he was posting.

And having people around to hate makes for a lively board.

[Roly Poly Oly-Garch]

Direct evidence?

Well yeah. That's usually good for getting them to believe you, unless they're really gonna dig their heels in.

But the problem I find interesting is the one where people will conflate "Your source was incorrect" with "Your source tried to deceive you." The second one triggers a much more defensive response, making it harder to get worthwhile discussion done.

It's more common in kids, but I guess it's sort of the same mechanism behind hearsay and rumors. If you trust the source as a person, you're more likely to trust the information they give you even if they aren't an authoritative source. The reaction isn't always as blatant as what I described in the OP.

Not sure if you had a specific example in mind, but I think this sort of thing happens a lot where someone has poisoned the well.

Example: The CDC recommends the following vaccination schedule.

Response: Don't believe Big Pharma's lies! Psychic Lilliana down at the Blue Orchid Holistic Care Clinic offers an herbal tincture that does the same thing as all the vaccinations and doesn't cause autism. The CDC is conspiring with Big Pharma to keep you from this information. She went on Dr. Oz to expose the government's efforts to discredit her.

In an example like that, it may be effective to counter with a somewhat discordian-informed plausibility argument.

Is it more plausible that thousands of scientists, beaureaucrats, politicians, and business executives could all get together and be efficient and organized enough to pull off such a grand deception, or that one person is trying to sell you snake oil?

The reason why it's so easy to poison the well with conspiratorial accusations is that it's very easy for people to look at the power imbalance between a monolith like Big Pharma and a much smaller player like Psychic Lilliana (who is probably already the head of a multi-million dollar company by the time she appears on Dr. Oz). But if people stop focusing for a minute on the difference in fire-power between a battleship and a speed boat, and instead look at the difference in their maneuverability, it suggests a very different likelihood.