In 2016 and again in 2018, I interviewed an incredible academic @SusanBenesch who studies dangerous speech by leaders that incites mass violence around the world. She could have predicted yesterday's events. https://www.washingtonpost.com/politics/2018/10/29/professor-who-defined-dangerous-speech-how-trumps-rhetoric-pittsburgh-are-linked/

Here is her criteria for what rises to dangerous speech: 1. A powerful speaker with a high degree of influence over the audience. 2. The audience has grievances and fears that the speaker can cultivate.
3. A speech act that is clearly understood as a call to violence.

4. A social or historical context that is propitious for violence, for a variety of reasons, including long-standing competition between groups for resources, lack of efforts to solve grievances or previous episodes of violence.

5. A means of dissemination that is influential in itself, for example because it is the sole or primary source of news for the relevant audience.