Thus the essence of freedom of opinion is not in mere toleration as such, but in the debate which toleration provides: It is not in the venting of opinion, but in the confrontation of opinion. That this is the practical substance can readily be understood when we remember how differently we feel and act about the censorship and regulation of opinion purveyed by different media of communication. We find then that, in so far as the medium makes difficult the confrontation of opinion in debate, we are driven towards censorship and regulation.

There is, for example, the whispering campaign, the circulation of anonymous rumors by men who cannot be compelled to prove what they say. They put the utmost strain on our tolerance, and there are few who do not rejoice when the anonymous slanderer is caught, exposed, and punished. At a higher level there is the moving picture, a most powerful medium for conveying ideas, but a medium which does not permit debate. A moving picture cannot be answered effectively by another moving picture; in all free countries there is some censorship of the movies, and there would be more if the producers did not recognize their limitations by avoiding political controversy. There is then the radio. Here debate is difficult: It is not easy to make sure that the speaker is being answered in the presence of the same audience. Inevitably, there is some regulation of the radio.