I see karma on posts fluctuating (in particular going down) more than I would expect coming from other vote-based websites. Is downvoting really used here for posts that are not spam or trolling? Or do people just change their minds a lot?
The FAQ has: We encourage people to vote such that upvote means “I want to see more of this” and downvote means “I want to see less of this.” But I guess I’m surprised if people actually behave that way? And that some posts are controversial enough to receive active downvotes vs passive ignoring.
I like that you are trying to trying to make your approach to voting explicit.
I believe people will usually vote based on something like "Upvote if this is content represents what I think Lesswrong should be". It depends on the content of the post or the comment what this means exactly. In many cases it should mean whether a post or comment should contribute to truthfinding on a topic. This should imply, for example, that posts that contain empirical claims should contain some kind of empirical evidence, and that conclusions are valid. It also implies that the identity of the author should not be a reason for upvoting.
Compared to websites that do not have a voting-system, I see the disadvantage that anonymity of voting implies that you can judge things without giving and evaluating arguments. This does not matter very much as long as we are talking about content that is not very emotional. It matters when we are talking about politics; partisan fellow-feeling can then drive behavior.
(Personally, I get the impression that the pandemic situation has brought more politics to LW and that a certain kind of partisan voting has become more common, and I don't like this trend. But my sample is not yet large enough to form a good judgement.)