To be clear, I am not accusing President Trump of inciting violence in Gilroy or anywhere else. But he empowers hateful and potentially violent individuals with his divisive rhetoric and his unwillingness to unequivocally denounce white supremacy. Mr. Trump may be understandably worried about the course of congressional inquiries, but his aggressive and race-baiting responses have been beyond the pale. He has chosen a re-election strategy based on appealing to the kinds of hatred, fear and ignorance that can lead to violence.

We’ve seen this movie before in the radicalization of Muslims by internet sermons delivered by charismatic, father-figure clerics who inspire terrorism and martyrdom. The president has fallen short of calling for overt violence against minorities and immigrants, but unbalanced minds among us may fail to note the distinction. If a president paints people of color as the enemy, encourages them to be sent back to where they came from and implies that no humans want to live in certain American cities, he gives license to those who feel compelled to eradicate what Mr. Trump calls an infestation.