No research yet establishes whether hate speech escalates into violence.

Evidence

Psychologists still understand relatively little about the effective rebuttal of antilocutions, on the part of either outgroup targets or ingroup bystanders to those antilocutions. In addition, while the effects of the use of ethnophaulisms on hostile prejudice and on exclusion have received empirical confirmation, the plausible and very serious link between antilocutions and violence is woefully in need of research. — , Rudman, Laurie A - On the Nature of…, 1295