They mean whatever the upvoter wants them to mean: agreement, approval, or a meant-to-click-downvote instead. In practical use, people often do upvote because they agree.
So I'm a newbie here, my account is less than a year old, god knows I've trolled and flamed my share, etc. But when I first joined, I saw the guideline/notion that upvotes should indicate contribution to discussion rather than agreement and was impressed. I'd be sad if this position was abandoned. Upvoting for contribution to discussion promotes good discussion. Upvoting for agreement promotes hivemind, of whichever variety.
In 2009, I wrote a little parody of the Zen of Python that includes a bit about what I felt upvotes were/should be used for: http://marcuscavanaugh.com/zen-of-hn/ -- I think that regardless of what guidelines were created initially, people do upvote as agreement, whether we like it or not.
I like upvotes as an expression of agreement because it gives an indication of the truthiness of the comment (wisdom of the crowd). If someone says something in a field I'm not familiar with, and I don't know if they're right or not, I know that the following will occur:
- If they're right, people will upvote.
- If they're wrong, people will either downvote or reply stating why they're wrong.
And since I don't think any of us want comments like "I Agree", upvotes are our only option for providing a vote of confidence in a comment.
But you're only going to up vote things that you agree with that also add to the conversation. Of course people up vote things they agree with, but in the case of something like the comment that started this all off, did it really add much to the conversation? I didn't think so, but it wasn't frivolous enough for me to down vote it. You're free to disagree and up vote all you want.
As a side note: truthiness, as defined by Colbert [1] isn't something that a crowd can tell you. It's something that only your gut can tell you. And my gut says that your comment wants a burrito.
The only situation where I'll upvote or downvote based on "agreement" or "disagreement" is statements of fact--and even then, inane statements of fact that don't contribute to the discussion, I don't upvote.
