Many common people appear to have acquired roles (from their commonly experienced contexts) that effectively make them dumber any time they do anything at all. And they get used to this. And then, other people come along and suggest something like ‘the Earth is actually flat’ or ‘words have meanings’ or ‘the President is patriotic’. And they get dumber, and that feels familiar, and so the process goes on until they come into approximate intellectual equivalence with, for example, a belt loop.