Democratic presidential aspirants should not feel obligated to self-flagellate to win back the public trust. The what-did-they-know-and-when-did-they-know-it media frenzy was just getting started, with Democratic officeholders being pressed by last week’s Sunday morning talk show hosts whether they “got it wrong” on Joe Biden’s fitness, did they “see much” infirmity, and do they “bear some responsibility” for his initial decision to run for re-election. Then we learned later on Sunday that Biden has an aggressive form of prostate cancer, and a fresh wave of conspiracy theorizing has begun. After Biden’s office issued a statement, Donald Trump Jr. baselessly suggested the...