Madison’s design has proved durable. But what would happen to American democracy if, one day in the early 21st century, a technology appeared that—over the course of a decade—changed several fundamental parameters of social and political life? What if this technology greatly increased the amount of “mutual animosity” and the speed at which outrage spread? Might we witness the political equivalent of buildings collapsing, birds falling from the sky, and the Earth moving closer to the sun?