Apply As Needed To The Affected Area

“The higher, pretentious form of stupidity stands only too often in crass opposition to [its] honorable form. It is not so much lack of intelligence as failure of intelligence, for the reason that it presumes to accomplishments to which it has no right … The stupidity this addresses is no mental illness, yet it is most lethal; a dangerous disease of the mind that endangers life itself. … [S]ince the ‘higher stupidity’ consists not in an inability to understand but in a refusal to understand, any healing or reversal of it will not occur through rational argumentation, through a greater accumulation of data and knowledge, or through experiencing new and different feelings … We may say that the reversal of a spiritual sickness must entail a spiritual cure.”

—One crucial word from How to Be a Stoic, Jan 19, 2016

This is stupidity as the willful ignorance of the unwise. Not mentally ill, no, but seriously and actively and obdurately mistaken. ἀμαθίᾳ :Amathia.