Freedom of speech is indispensable to a free and civilized society, yet this precious right is increasingly under attack today. Islamic totalitarians repeatedly threaten and kill those deemed blasphemers, while our political leaders stand idly by, and many intellectuals blame the victims. College students seek "trigger warnings" and "safe spaces" from controversial ideas and fly into fits of rage at the slightest offense. The government harasses tea party groups, preventing them from speaking out during an election, and it investigates oil companies and advocacy groups for the "crime" of...