Is there a word or fixed phrase / idiom for a vicious circle of obtuseness? [duplicate]

I recently told my father-in-law that I thought he was being obtuse, and he then acted as if he didn’t understand the concept of being obtuse. I feel like there’s a word for this. What would we call such a situation as this?

OED:

dissemble, v.1 1. transitive. To alter or disguise the semblance of (one's character, a feeling, design, or action) so as to conceal, or deceive as to, its real nature; to give a false or feigned semblance to; to cloak or disguise by a feigned appearance.

a1535 T. More Hist. Richard III in Wks. (1557) 65/1 Some..not able to dissemble theyr sorow, were faine at his backe to turne their face to the wall.

1709 Tatler No. 32. ⁋4 With an Air of great Distance, mixed with a certain Indifference, by which he could dissemble Dissimulation.

MW

dissemble

transitive verb

1 : to hide under a false appearance dissembling the facts 2 : to put on the appearance of : simulate She lay down and dissembled sleep.

intransitive verb

: to put on a false appearance : conceal facts, intentions, or feelings under some pretense He had dissembled about the risks involved.