evidence: On Oct. 17, I attended the Al Smith Dinner, an annual charity gala in New York City. Political big-shots mingle with media celebrities and corporate executives. It is always an entertaining experience. This year’s keynote address was by retired Marine Corps Gen. James Mattis, President Donald Trump’s erstwhile secretary of defense. Trump once praised Mattis profusely, but more recently has made him the object of his scorn, calling him "the world’s most overrated general." (Full disclosure: I know Jim Mattis and can report that he is among the finest officers I have met since I first donned a uniform 53 years ago.) [...] The barb was doubly surprising given Mattis’ previous reluctance to criticize his former commander in chief, a decision that has garnered its fair share of criticism. But there’s a reason for Mattis’ reluctance. Generals in Mattis’ position, even those who are retired, do not criticize the sitting president. Until this administration, Mattis’ joke would have been unthinkable. And yet, Mattis is merely the latest in a line of commanding officers who have recently rebuked the president’s decisions. This collective decision to go against such entrenched military traditions should give their warnings even more weight. When the generals are speaking out, something is really wrong.