There is some ancient comment by pg that says something to the effect of "downvoting to express disagreement is fine," that people always bring out when this discussion happens. I think that should change. Downvoting simply because you disagree should not be the desired behavior, and flagging for disagreement especially shouldn't be desired.

I can't say that I live up to that standard. But, I do vouch probably 10x more than I flag. Browsing with showdead on, I get to see an interesting view of HN, and there are some bits of gold in the sluice there.