The attempted assassination of former US President Donald Trump, while undeniably shocking, was not altogether surprising. It was just the latest blow in a steady drumbeat of political violence that has only grown louder over the last decade.

This reflects the fact that political violence is “in the air”, and is increasingly being regarded by many Americans — and citizens of nations around the worlds — as a justifiable response to political disagreement.

What does it take for such violence to become thinkable? Do we possess the democratic antibodies to resist the contagion of violence?