In May 1958, in a hospital laboratory in Paris that had not existed a year before, a 32-year-old pediatrician named Marthe Gautier looked at cells from a boy with Down syndrome and counted 47 chromosomes. Two years earlier, Tjio and Levan had shown that the normal human count was 46. Nobody had yet …
Last week I stopped where the problem got technical and interesting: when a constraint works not by catching errors, but by making certain errors unwritable. A comment pointed out I skipped the deeper question—what happens when a rule that is logically sound takes decades to become standard …