Today I learned (again)

When they say, "moss only grows on the north side of a tree", and you show them a tree with moss all around the trunk, and they cleave to the erroneous, that person is of the willfully ignorant ilk.

There is no need to conduct a longitudinal study or a remedial crash course because this is tried and true:

“He who knows not and knows not he knows not: he is a fool - shun him.
He who knows not and knows he knows not: he is simple - teach him.
He who knows and knows not he knows: he is asleep - wake him.
He who knows and knows he knows: he is wise - follow him.”