When someone says something we disagree with, should we shut them up? In 1927, Supreme Court Justice Louis Brandeis had an answer: "The remedy to be applied is more speech, not enforced silence." Well, in that case, the internet should have solved everything, notes correspondent David Pogue – it's nothing but more speech. And yet lately, the news is full of stories about people trying to limit other people's expression. The free-speech erosion is even happening in schools. Since January last year, according to PEN America, Republican lawmakers have introduced more than 150 state laws that would restrict how teachers...