I have covid, which already seems to be receding. My immediate temptation is to attribute this to having been vaccinated in Feb-March. Of course I have a mild case. That's what happens when you are vaccinated. Ain't I smart?
That narrative could in fact be true. It is the most likely true narrative. Yet it is also the narrative that I want to be true, the self-serving one. That doesn't really prove the case though, does it? If I had not been vaccinated, I might have gotten covid at a different time, maybe more severe, maybe less severe. Or the diminution of symptoms from getting vaccinated then might be so minimal as to be worth no more than a shrug. Or I might have done the hokey-pokey in a different order this month and gotten no virus at all. I blame Jane Russell. Frankly, if one changes any tiny thing, there is no telling what happens. Asimov wrote "The Ends of Eternity" in the 50s, but Ray Bradbury and others have also had a go at it.
Even knowing this, it is hard to fight against it. "But mine is the most likely scenario," I whine. Maybe so, but that's not enough. It only matters over a thousand repetitions, and even then, it might be only an emerging outline.
Grim mentioned that there are times when a single counter-example can be meaningful against an absolute claim. I would go even a step further, and note that for highly declarative claims, even a few counter-examples can raise a red flag. "Marines who enlist after age 20 are almost always..." or "Episcopalians secretly don't like black people, whatever they say..." or "Southerners refuse to answer the question of..." It is not impossible that the person making the claim might have really solid numbers backing that up. Yet if I know four people in that category, and none of them fit that description, then I don't mind raising an objection. I might turn out to be wrong, but against a nearly-absolutist claim, I'll take the risk.
Yet we know, from my N=1 post and just having to listen to jibroneys who somehow get paid to assert stupid stuff that people want to hear, that people will keep saying this anyway. You say that fourth-graders don't care much about masks, but my Dylan hates them, or My son-in-law eats nothing but vegan and you never saw anyone in better shape.
I have no solution. Just let us not do it, even when a possible PR victory is within our grasp.