On Sunday, Joe Biden disclosed that he has an aggressive form of prostate cancer that has spread to the bone, which means that it can be managed but not cured. The news roughly coincided with the promotion of a book whose authors argue that his inner circle engaged in misdirection, if not obfuscation, about his mental acuity near the end of his term. Sympathy quickly gave way to speculation regarding what Biden had known about his cancer, and when he’d known it. Donald Trump said that he felt “very badly,” but that “people should try and find out what happened” and that “somebody is not telling the facts.”