Post a response. Explain why you disagree. Use Reddit if you feel it's important to cast votes based your level of agreement with others. If it's a troll post then ignore it and move on to something worthy of a response. Click hide if you don't want to see a post.

While voting is pitched by most sites as a way to indicate quality, the reality is that most people vote based on whether they agree or disagree. The 'I disagree' mentality is everything wrong with voting systems on most sites. We don't need that here.