Joe Biden, Alexandria Ocasio-Cortez, and the Shaky Unity of the Democratic National Convention

On Day Two of the Democratic National Convention, the Party’s recent past kept ghosting in and out. Before the networks had even begun their broadcasts, the Party rolled through half a century of its own history: Jimmy and Rosalynn Carter, from Georgia, and then Caroline Kennedy and her son in front of the unpainted shingles of a Cape Cod home, and, finally, Bill Clinton, sitting on a flowered couch at his home in Chappaqua, New York. Clinton and Joe Biden form generational bookends—one moderate icon hailing another. But there was...