If you’re a working journalist and you believe that Donald J. Trump is a demagogue playing to the nation’s worst racist and nationalistic tendencies, that he cozies up to anti-American dictators and that he would be dangerous with control of the United States nuclear codes, how the heck are you supposed to cover him?

Because if you believe all of those things, you have to throw out the textbook American journalism has been using for the better part of the past half-century, if not longer, and approach it in a way you’ve never approached anything in your career. If you view a Trump presidency as something that’s potentially dangerous, then your reporting is going to reflect that. You would move closer than you’ve ever been to being oppositional. That’s uncomfortable and uncharted territory for every mainstream, nonopinion journalist I’ve ever known, and by normal standards, untenable.

But the question that everyone is grappling with is: Do normal standards apply? And if they don’t, what should take their place?

Covering Mr. Trump as an abnormal and potentially dangerous candidate is more than just a shock to the journalistic system. It threatens to throw the advantage to his news conference-averse opponent, Hillary Clinton, who should draw plenty more tough-minded coverage herself. She proved that again last week with her assertion on “Fox News Sunday” that James Comey, director of the Federal Bureau of Investigation, had declared her to be truthful in her answers about her decision to use a private email server for official State Department business — a grossly misleading interpretation of an F.B.I. report that pointed up various falsehoods in her public explanations.