Early last year, in an article in The New York Times Magazine, I defined what I called a “Megyn moment,” in a profile of the Fox News host Megyn Kelly:

“When you, a Fox guest — maybe a regular guest or even an official contributor — are pursuing a line of argument that seems perfectly congruent with the Fox worldview, only to have Kelly seize on some part of it and call it out as nonsense, maybe even turn it back on you.”

When I wrote that article, the Megyn moment was notable because it was so unusual.

Normally, if guests hewed close to Fox News’s prime-time perspective (President Obama, woefully incompetent or frighteningly efficient; Democrats, bad, especially Hillary Clinton; Republicans good, mostly all of them), they were pretty much safe from challenge.

In letting Ms. Kelly break from that orthodoxy here and there, the Fox News chief Roger Ailes seemed to be experimenting with ways to expand his channel’s audience, which was older, whiter and in danger of atrophying despite its longtime perch atop the cable news ratings. Ms. Kelly’s youth and divergent approach had the potential to draw in new viewers. The question at the time was, how far would he be willing to let these Megyn moments go? And what did that mean for Fox?