I want to flag a comment, "I disagree, but this is the most persuasive point someone has made."
In theory, that is my understanding of the voting system on HN. Based on the downvotes I have received over the years, it's obviously not perfect in that respect. But upvote the comments that contribute positively to the conversation, and you might rarely downvote a comment that detracts. I click the up button for plenty of comments with which I have strong disagreement. But if it's a well-thought comment that makes me have to think about a good counter if I disagree, then it's worth an up click.
But what is most interesting to me is, "I disagree with your conclusion (or the assumptions you are starting from), but I think your argument is well said."
I'd often like to de-emphasize the people that I agree with. I don't need my own opinion echoed back to me so much, thanks. That's what FB, Reddit, HN seem to tend to do.
Or, they find "engaging" content. Which is normally obnoxious, offensive, and flat-out wrong in uninteresting ways. They feed on my pugnacious attitude for clicks.
I'd rather spend more time talking with people who accept the "Principle of Charity" as sacrosanct, than talking with people who will quibble about minor points.
In theory, that is my understanding of the voting system on HN. Based on the downvotes I have received over the years, it's obviously not perfect in that respect. But upvote the comments that contribute positively to the conversation, and you might rarely downvote a comment that detracts. I click the up button for plenty of comments with which I have strong disagreement. But if it's a well-thought comment that makes me have to think about a good counter if I disagree, then it's worth an up click.