Think of the antivaxers who are ideologically committed to a world in which human beings do not have a shared destiny, meaning that no one has a moral claim over the choices you make. Motivated reasoning lets those people rationalize their way into imagining that measles - a deadly and ferociously contagious disease that was a scourge for millennia until we all but extinguished it - was no big deal:
https://en.wikipedia.org/wiki/Measles:_A_Dangerous_Illness
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