This week is the anniversary of the tragic day in 1963 [11/22/63, 35 years ago today] when John F. Kennedy was assassinated on the streets of Dallas. Looking back, we can see that Kennedy's death marked a turning point, when the political consensus of the time gave way to the confrontational politics that we associate with the 1960s. The upheavals that followed -- along with the bitter partisanship that disfigured political life in the last third of the century, and whose echoes we still hear today -- can be traced back to that day in Dallas. The terrorist attack of...