For decades, young people’s leftward leanings were considered an iron law of politics.

“If people are not conservative at 40, they have no head,” Winston Churchill probably never said, “but if they are not liberal at 20, they have no heart.” From John F. Kennedy, Bill Clinton and Tony Blair to Barack Obama and Jacinda Ardern, the leading lights of the left have regularly built political careers on the promise of youthful progressivism.

This pattern is so culturally ingrained that it is largely taken for granted. But electoral outcomes in many Western democracies have begun to suggest a very different dynamic. In the first round of the French presidential elections this month, Emmanuel Macron achieved only a narrow victory (27.85%) over the right-wing populist Marine le Pen (23.15%). His success was based not so much on the fervor of the young as on the caution — and alarm — of older voters.