Let's see, here are the possibilities:
1. Someone means well, you interpret it as them meaning well and respond accordingly. Everything is fine and dandy, everyone's happy. 2. Someone means well, and you interpret them as meaning ill, and respond accordingly. Now you are angry for no reason, they have had the experience of making a well meaning comment and being shot down for it. Everyone is miserable. 3. Someone means ill, and you interpret it as them meaning ill, and respond accordingly. Now they have gotten the thrill of getting through to you (remember, they mean ill, so that is their intent), and you are angry (for a good reason). You've made yourself miserable and a troll happy. 4. Someone means ill, and you interpret it as them meaning well and respond accordingly. Now they don't get the pleasure of having bothered you, you have shrugged it off an it's not great loss to you. You are now happier than option 3, and they haven't had a chance to hurt you like they meant to.
Of course, real life isn't quite a simple as that; but that does cover a very large number of possible interactions on the internet. By biasing yourself toward the most charitable interpretation of others comments, you reduce the risk of a simple misunderstanding leading to everyone being unhappy, reduce the risk of just giving a troll exactly what they want, and contribute to a more positive environment in general.
It really does help out in an awful lot of cases, and reduces friction dramatically if you always assume good faith unless you have very compelling evidence to the contrary.
Because doing so contributes to the community and not doing so harms it.
When you respond to the strongest interpretation of a comment, you're responding to what's most substantive in it. That raises the signal/noise ratio for everybody, and curiosity is what we're trying to optimize for.
For example, if somebody tells me "Angersock, you can go happily fuck yourself", I'm not going to expect them to be wishing me a rousing and cheerful round of masturbation--that is the "best possible light", but not the "strongest interpretation".
Properly handled, assuming the worst of a comment, articulating the argument you think is being made, and then rebutting it, is far better than just assuming the best--provided it's done civilly, of course.
I don't think it's a stretch, mutatis mutandis, to take even a comment like "go fuck yourself" charitably. It could, indeed probably mostly does, mean "I'm angry about something unrelated."
1. http://en.wikipedia.org/wiki/Principle_of_charity
2. https://hn.algolia.com/?query=author:dang%20principle%20of%2...
I don't think even at its strongest the PoC would require you to assume that the commenter was legitimately upset, only that the commenter was intending to express that they were upset.
The PoC only applies to interpreting what the intended message is, not to conclusions about its justification as would be necessary to support the interpretation that the commenter was legitimately upset.
http://c2.com/cgi/wiki?AssumeGoodFaith
I suspect it's a much older idea than that, probably dating back to the Enlightenment. It's closely related to the Principle of Charity, which was coined in 1958 but again, refers to a much older principle of logical discourse:
That's fascinating! Has anyone traced it to its precise origin there? I'd love to see that.
In his book A Theory of Justice, Rawls stated that citizens are obliged to act in good faith, and to assume good faith on the part of others until clear proof emerges to the contrary. They must recognize, in effect, that the system cannot meet everybody's claims at once and accept that at times they will be on the losing side.
And a good recent blog post [2]:
Several maxims guided me in doing this. I always assumed, for example, that the writers we were studying were always much smarter than I was. If they were not, why was I wasting my time and the students’ time by studying them? If I saw a mistake in their arguments, I supposed they saw it too and must have dealt with it, but where? So I looked for their way out, not mine.
[1] http://www.rbc.com/aboutus/letter/may_jun1995.html
[2] https://parentheticalpilgrim.wordpress.com/2015/03/14/good-f...
http://web.archive.org/web/20020502092511/http://www.usemod....
Wrongly assume the best: It quickly becomes apparent, things move forward, you may even steer things in a better direction.
Wrongly assume the worst: You look like a jerk, possibly demotivated people or made them feel bad, and now there is an air of conflict that needs to be ventilated by unnecessarily defensive comments.
The best outcome for HN is if we as a community converge on the right answer.
Now if someone brings argues poorly, but for the right answer, and then someone comes along and crushes the poor argument. Then the counter-arguer "wins" and succeeds in humiliating the "opponent". But the the wrong answer wins, and that is bad for the community
If on the other hand, someone comes along, reinforces the poor argument, and then brings a weak counterargument, then that gives the right answer a better chance of winning.
However, it takes two to tango; worthwhile discussion is a cooperative venture. There's systematic reasons why a forum is incapable of reaching a certain level. Take Twitter and misogyny. (Or HN for that matter; Twitter's rampant death threats shouldn't lower expectations when evaluating other forums.)