Facebook is well aware that its community wants a way to dislike something negative, rather than having to “like” everything.

Asked by a U.C. Davis law student during a public Q&A today if Facebook will ever add a dislike button, CEO Mark Zuckerberg said that the company is “thinking” about it, so that expressing a negative sentiment “ends up being a force for good.”

Zuckerberg acknowledged that the company knows that many people think the “like” sentiment is not appropriate for posts such as when someone is sick. But he seemed to quickly backtrack. “The like button is valuable because it’s a quick way to share a positive sentiment,” Zuckerberg said. “Some people have asked for a dislike button so they can say something isn’t good, and we’re not going to do that. I don’t think that’s good for the community.”

People have long asked for a dislike button, and the question was one of the most common among the thousands of people who had posted comments on the Facebook page for today’s Q&A with Zuckerberg. And the CEO, wearing the same grey T-shirt he always wears, said he knows where people are coming from.

“The thing I think are really valuable is there are more sentiments just than people like something,” he said. “There are things in people’s lives that are sad, or that or tragic, and people don’t want to Like them. We’ve talked about for a while how can people express a wider range of emotions like surprise.”