I feel as if even those of us who don’t know very much about Mariah Carey actually know rather a lot. I for one have long been wasting far too much of my cerebral cortex on the notorious demands on her riders over the years. The 20 white kittens. The 100 doves. The, erm, tall leafy plants. If I could just unknow this stuff, maybe I would be able to recall what happened in the last chapter of the book I am reading.

And now here is something else I will never be able to unremember. Her declaration in this month’s Harper’s Bazaar that she is refusing to age. “I don’t allow it — it just doesn’t happen,” she says. “I don’t know time. I don’t know numbers. I do not acknowledge time.”

This statement is not only squatting in my brain but frying it. I mean, right. Sure. OK. Whatever you say, Mariah. You don’t know time. The problem is that, even with all the will, and money, and plastic surgery, in the world, time knows you. It’s annoying like that, time. You can decide that you aren’t having anything to do with it but it will continue to be relentlessly on your case. Like a bad ex. Or Always Be My Baby on repeat.

• Mariah Carey: Ageing doesn’t happen to me and I won’t allow it

As for not knowing numbers, I must admit that I frequently forget that I am 53. I am not sure that is quite what Carey means, however. Not least because instead I think I am 52. Indeed, while we are on the pesky subject of numbers, particularly double-digit ones that start with a 5, Carey herself is 56. Or at least she would be if she acknowledged such things.

In truth, all that Carey has done is given voice to the delusion long made manifest in the faces of women across entertainment. She is merely saying what they are attempting to do, which is to eradicate any sign that they are growing older.

Carey’s face on the cover of Harper’s Bazaar is, of course, as disconcertingly smooth and shiny as a grapefruit. But, let’s be clear, a face like that doesn’t look ageless. It looks other. There’s a difference between positive thinking and delusional thinking, not that living in fear and/or denial of ageing has anything positive about it, in truth. And there’s a difference in what plastic surgery promises to give someone and what it actually delivers.

Perhaps the most striking recent example of woman as pomelo is Kris Jenner, who has remade a face that had already been remade, and who, as a result, at 69 really does look quite remarkably like her daughter Kim Kardashian, who is 44. Not that — and warning, this stuff can get confusing — Kim Kardashian looks like Kim Kardashian, given all the work she has had. She also doesn’t look 44. And neither of them looks entirely human.

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And there’s the rub. Let me hand over to Jane Fonda at this point, who is now 87 but shared with Vogue, when she was a whippersnapper of 84, her views on ageing. “Just because you’re a certain age doesn’t mean you have to give up on life, give up on having fun, give up on having boyfriends or girlfriends, making new friends or whatever you want to do,” she said.

Fonda’s an especially interesting case in this context because she has mucked around with her face too. “I had a facelift and I stopped because I don’t want to look distorted,” she continued. “I’m not proud of the fact that I had [one].”

Her advice for how to look your best as you grow older? “I stay moisturised, I sleep, I move, I stay out of the sun and I have good friends who make me laugh. Laughter is a good thing too.”

And, in marked contrast to Carey, Fonda says, “I always tell people what my age is.”