And then, after a few weeks, the tone in France began to shift. Intellectuals began voicing their concerns that such denunciations were going too far. Ms. Deneuve, in a televised interview, declared: “I will certainly not defend Harvey Weinstein. I have never had much consideration for him. I always felt there was something disturbing about him.” However, she said she found extremely shocking “what is happening on social networks around it. It is excessive.” And she wasn’t alone.

There was something about the recent big displays of American sisterhood laid out on the cover of Time magazine, and at the Golden Globes ceremony, where women turned up dressed in black with their “Time’s Up” pins, that seemed to trigger Gallic irritation. In this week’s letter, the signatories worried that the “thought police” were out and that anyone who voiced disagreement would be called complicit and a traitor. They noted that women are not children who need protecting. But there was also this: “We do not recognize ourselves in this feminism,” they said, which “takes on a hatred of men and of sexuality.”

Call it a cliché if you like, but ours is a culture that, for better and for worse, views seduction as a harmless and pleasurable game, dating back to the days of medieval “amour courtois.” As a result, there has been a kind of harmony between the sexes that is particularly French. This does not mean that sexism doesn’t exist in France — of course it does. It also doesn’t mean we don’t disapprove of the actions of men like Mr. Weinstein. What it does mean is that we are wary of things that might disturb this harmony.

And in the past 20 years or so, a new French feminism has emerged — an American import. It has embraced this rather alien brand of anti-men paranoia that Ms. de Beauvoir described; it took control of #MeToo in France, and this same form of feminism has been very vocal against the Deneuve letter. Today, Frenchwomen, too, have the girls’ nights out that Ms. de Beauvoir once found so foreign.

When “America Day by Day” was published, American women were incensed. The novelist Mary McCarthy couldn’t stand the book. “Mademoiselle Gulliver en Amérique,” she wrote, “who descended from the plane as from a space ship, wearing metaphorical goggles: eager as a little girl to taste the rock-candy delights of this materialistic moon civilization.”

Ms. de Beauvoir was in many ways easy to mock: She wrote in a direct, authoritative, self-assured way that may have sounded arrogant to readers unaccustomed to its bluntness. But the epidermic reaction across the Atlantic, to both Ms. de Beauvoir and to that letter, may in fact underscore the sharpness of the French critique. To many of us in France, Simone de Beauvoir could have been writing yesterday: “Relations between men and women in America are one of permanent war. They don’t seem to actually like each other. There seems to be no possible friendship between them. They distrust each other, lack generosity in dealing with one another. Their relationship is often made of small vexations, little disputes, and short-lived triumphs.”