The recent flashpoints in conflicts over monuments and public art have usually been Confederate generals or problematic founding fathers. In Philadelphia, protesters have found another target: Frank Rizzo, the law-and-order mayor who presided over the city in the 1970s. A ten-foot tall bronze likeness of him stands, waving awkwardly in an ill-fitting suit, in the concrete plaza in front of the Municipal Services building. Demands to remove the statue have been growing ever louder.  

Hizzoner has …