‘It got nowhere near the publicity and caused nowhere near the stir of his 1995 essay “Bowling Alone,” about Americans’ increasing social isolation. But more recent work by the Harvard political scientist Robert D. Putnam is perhaps more controversial: his finding (2007 lecture here) that ethnic diversity isn’t an unqualified good — that diversity, “at least in the short run, seems to bring out the turtle in all of us,” as we withdraw from collective life, hunker down in front of the TV and distrust people around us, regardless of skin color.’ (New York Times )