What do you do after you run New York City into the ground? You teach at Columbia. “David N. Dinkins is Professor in the Practice of Public Affairs,” his faculty website proclaims. “He also serves on SIPA’s Advisory Board, chairs the Earth Institute’s NYC Sustainable Development Initiative, and hosts the annual Dinkins Leadership and Public Policy Forum.” “In 2003, the David N. Dinkins Professorship in the Practice of Urban and Public Affairs was established at Columbia University. The 106th Mayor of the City of New York, Mr. Dinkins began his career in public service in 1966 in the New York...