People don’t commit violence against other groups - or even condone it - spontaneously. First they must be taught to see other people as pests, vermin, aliens, or threats. Malicious leaders often use the same types of rhetoric to do this, in myriad cultures, languages, countries, and historical periods. We call this Dangerous Speech. Violence might be prevented by making it less abundant or less convincing. We work to find the best ways to do this – while protecting freedom of expression.