Are you sure that someone went ahead and did that and that you didn't just have a few downvotes of old top-level posts happen to occur within a short span of each other? Or alternatively someone could have been going through and reading your comments systematically and they disagreed with a lot more than they agreed so they downvoted more than they upvoted?

Nah, they were dropping in clumps of like 6 a piece every few seconds as I refreshed the page. It happens to other people too.

Is there any opinion or attitude of yours that you think would be particularly likely to trigger this sort of response?

Partially it is because I write about things like Thomism in a really obscure way that appears masturbatory. I generally disregard local norms of communication. People have no idea why I do this but they assume it's because I am either insane, extremely prone to compartmentalization, or choosing to defect against the tribe for some reason. It seems to them that I consistently choose not to provide evidence that would lead them to expect otherwise. I assume that they think that allowing such blatant defection makes LW look bad or generally sets a bad precedent and so feel justified in downvoting many of my comments into oblivion and occasionally downvoting all my posts. They don't often downvote all my comments too. Maybe they're trying to be subtle? The first time I checked LW and had 300 karma less than the previous day I wasn't quite sure what had happened and just ignored it. It's easy to miss.

The most recent mass downvoting could have been caused by one of two things. I think it's because I repeatedly told Eliezer that he sucks at reading in a very public thread but I'm not certain of that.