Liberal democracies have in fact developed a number of sound rules for determining where free speech must be curtailed.  The United States has perhaps the most liberal rules governing free speech, and even here we have standards.  To wit, Schenck v. United States: http://en.wikipedia.org/wiki/Schenck_v._United_States.  Speech that exhorts people to ~actual~ violence is prohibited.  Speech that offends people, perhaps making them angry enough to do violence, is not; rather, the state exercises its power to prevent the violence, not the speech.

 The troubling modern trend that Mr. Moynihan addresses is the failure of society's to understand this distinction between overtly encouraging violence and merely offending groups of people.  This is no trivial matter.  When government fails to guarantee the security of the speaker, bowing instead to threats of violence or social unrest, we lose everything.

 Including ~perspective~.  Speech that angers people, that is offensive, crude, or moronic, is no great threat to any healthy society.  Trust in the ability of people to see what is self-evident in a statement, and the few who cannot comprehend it do not matter.  The majority of Europeans are not swayed by racist tripe, just as the majority of Muslims are not rendered terrorists by the ranting of ignorant extremists.  It's time to stop wringing our hands and engage these ideas in open debate, while the government protects all participants' right to do so.