This week, America lost more than a man. We lost a voice that embodied one of the most quintessentially American acts imaginable: peacefully debating ideas in the public square. Charlie Kirk was not engaged in violence. He was not plotting destruction. He was doing something that has been at the very heart of our national identity since the founding of this Republic—he was exchanging perspectives with fellow citizens in spirited conversation.   That is why his murder cuts so deeply. It...