There are two possible explanations for James Comey’s decision to announce last week that he was examining emails that “appear to be pertinent” to the investigation of Hillary Clinton’s use of a private email server.

One explanation, which I tend to believe, is that Comey, the director of the F.B.I., set out to interfere in the campaign on behalf of the Republican Party, a shocking act that would render him unfit for his powerful office.

(In that scenario, the aim may have not primarily been to help Donald Trump, but to preserve the Republican majorities in Congress, which suddenly seemed in danger this fall. Can you imagine how intense the pressure on Comey from the Hill must have been following his announcement this summer that the investigation was being closed?)

The other possible explanation is that he acted out of what you might charitably call a sense of moral rectitude. I think it’s better described as self-righteousness — a dangerous current in modern right-wing politics that has its roots in the rise of the Moral Majority, which aimed to make politics a choice between good values (the right’s) and bad values (the left’s) rather than a competition of ideas.