Liberal constitutions accept some principle of protection of free speech, but its scope and rationale are contested. Speech may include various forms of expression: displaying paintings, wearing political slogans, or burning flags, for example. On the other hand, some forms of speech (shouting ‘fire’ in a crowded theatre; ordering or encouraging a person to use violence on another) seem to deserve no special legal protection. The main positive argument for special protection of free speech is that this protection generates special benefits, either promoting the discovery of truth and error, or serving as a necessary part of educated political decision-making. A negative argument is that the harms caused by speech are somehow less significant than those caused by other actions (‘sticks and stones may break my bones, but words will never hurt me’). Or, if harm does ensue, it may be that the hearer bears some responsibility, for instance by being disposed to particular kinds of sensitivity. This, however, is contested. A principled argument for free speech is that silencing someone is a particular trespass against their dignity and against the respect due to a free agent. A pragmatic argument for the principle is that speech is an area in which legislatures are particularly tempted to illiberal intrusion.