In a recent documentary exploring his work, Harvard professor Robert Putnam describes the experience of standing on the national mall for John F. Kennedy’s 1961 inauguration. As Kennedy intoned the iconic phrase “Ask not what your country can do for you, but what you can do for your country,” Putnam felt it was “like a trumpet sounding reveille” to a new generation of American dynamism. In the film, Putnam reflects during the twilight of his life and realizes that “it was not reveille, but taps.” The early 1960s, Putnam discovered, were the high-water mark for American social trust, which has…