A Facebook spokesman replied that the company made its decision out of respect for free expression and faith that a controversial ad will receive intense scrutiny in today’s media world. “In mature democracies with a free press, political speech is already arguably the most scrutinized speech there is,” the spokesman said.

Not long after, Zuckerberg made a more complete defense of Facebook’s policies in a speech at Georgetown University.* The company faces a wide variety of problems when it comes to freedom of expression, he said. Some of those problems have solutions that have broad public support. For example, there is a consensus that Facebook should censor incitements to violence, or child pornography, or terroristic threats.

But political speech is something different. Much of it is supposed to highlight differences in opinion. It targets divisions in the electorate. It can be rough. And that has always been the case.