I know of no similar decisive break by Sanders with his past comments and associations. Yes, he now downplays his association with the S.W.P. and clears his throat about his opposition to the Castros and Ortegas of the world. Good for him, and it’s not for me to doubt his sincerity.

But I do doubt his seriousness. In America’s 46-year Cold War with some of the vilest regimes in history, Sanders’s main contribution was loudly to find fault with America while remaining remarkably mum about the sins of the other side — when he wasn’t finding occasions to praise them. The least he can do is acknowledge that he was wrong.

The Cold War is long over, and Sanders deserves to be judged chiefly on the merits of his proposals and the strength of his character. I have serious doubts on the first score, but that’s for future columns. For now, what needs saying is that a man who refuses to make an honest break with the worst convictions of his youth should never be entrusted with the presidency.