This past week, Americans watched as the hallowed chambers of the Capitol were overrun and defiled, not by some foreign enemy of democracy but a mob of their fellow citizens.

And then they tried to make sense of it.

In letters to the editor and posts on social media, they raised their voices. In Iowa, a lifelong Republican mourned the shredding of the country’s political norms. In Tennessee, a pastor and activist, alarmed by the rioters’ behavior, wondered if it might provide an impetus for change. In Mississippi, a young teacher worried what her students will make of the violence.

Days later,...