What decision did those that were already aware of it make, in order to optimise this activity?
Acknowledge the other person - their intent, the effort they've made, and/or the things they've got right. Be sincere rather than superior. E.g. to an anti-vaccine conspiracy theorist, I might say "I understand why you're suspicious of big pharma, and I know that you're concerned for the health of children. However, I believe vaccines do far more good than harm, and here's why..."
This helps take heat out of the exchange, by making it clear (on an emotional as well as intellectual level) that you aren't attacking them. If they don't feel themselves and their status under attack, and you demonstrate an interest in understanding them, people can feel more secure and be more open to understanding what you're saying.
It's not infallible of course, and it's not enough on its own. Follow some of the other good suggestions on this page, as well.
E.g. if you're making an effort and the other person is still on the attack, disengaging is wise. My preference is to briefly say why I'm disengaging, wish the other person well, quit, and stop following the thread (unsubscribe, unfollow depending on the platform)..
I wont be the only one here who "wastes time" arguing about things they care about online (note: I am referring to web forums and things like subreddits, I am not including Less Wrong whose dynamic is completely different). It seems like something that is worth optimising in some direction.
The theory behind it is that one should expose themselves to counter-arguments allowing their claims to be attacked so they that have a chance to substantiate them or reject them upon realising they are mistaken.
In practice they generally follow a pattern that starts with people pointing out what they believe are mistakes then ignoring or intentionally misunderstanding the other party when he refutes or backs up claims.. and ends up with insults, patronising sarcastic remarks and nobody changing their mind about anything.
I don't particularly care about changing other peoples minds to make them agree with me (well, it would be great but I think it's practically impossible) so one thing I would like is for both people to at least end up feeling good.
So I'm interested in three things: Do other LWers recognize this pattern now that I have mentioned it? What decision did those that were already aware of it make, in order to optimise this activity?