Ninety minutes later, after the final exchanges, the room voted again. And the result was stunning: Bannon had triumphed, crushing my side of the argument, 57-43.

The hall gasped. As an attendee told me later, people looked at their neighbors with surprise and fear. Bannon grinned in triumph. We shook hands, I congratulated him on his upset victory: “Just like 2016,” I said. Inwardly, though, I felt dismay. The room had not applauded or laughed any more approvingly at the end of Bannon’s presentation than at the start. He had not carried his hearers. Through some horrible fault of my own, I must have lost them.

But that loss, although my fault, was not my problem alone. I had by my apparent failure confirmed every criticism of the debate critics. I had helped to provide a platform in an inhospitable city and country to Bannonism—and instead of offering hope, I had contributed to despair. I had lent my name and my energy to powerfully disseminating and legitimating exactly what I had hoped to expose and refute. I had undertaken a great responsibility and had somehow bungled it.