I just turned 78, and frankly I’m scared about what might come down Thursday evening when the oldest candidates ever to compete in a presidential race debate each other. I’m less worried that Joe Biden will suffer a mental lapse or physically stumble than I am that Biden will look weak and Donald Trump appear strong. One of Trump’s most successful ploys has been to frame the upcoming election as a contest between strength and weakness, and to convince many Americans that stridency and pugnacity are signs of strength while truth and humility signal weakness. In 1960, when I watched...