My problem with downvoting-for-disagreement is that it is not symmetrical to upvoting-for-agreement. If someone makes a quality comment, but it happens to be a

My problem with downvoting-for-disagreement is that it is not symmetrical to upvoting-for-agreement. If someone makes a quality comment, but it happens to be an unpopular view, and they get voted negative, they are less likely to express their view in the future... and we are the poorer for it. No one wants a monoculture. If that same person makes the same comment, and people merely upvote the opposing viewpoint, then neither person is being 'discouraged' from contributing. One is just being encouraged more than the other. I realize it's all just a number and shouldn't matter, but we are human beings and it does... seeing someone else get told "good job" isn't near as bad as someone telling you "bad job"... especially when you thought that you had done something good by contributing a useful viewpoint. (Obviously none of this applies to trolls/spam and things that are outright false... people shouldn't say things they can't provide evidence for.) To make a rather tenuous analogy: If you don't like a product, you don't get to take money away from the company that makes that product. The best you can do is give money to their competitor. And to extend that, you can only take money (fines) from some company if they do something illegal. Here doing something 'illegal' is trolling/spamming.