Problem: Proverbs 22:15 teaches that “Foolishness is bound up in the heart of a child, But the rod of correction will drive it far from him.” But, according to this verse, foolishness is irremediable, because, “Though you grind a fool in a mortar with a pestle along with crushed grain, yet his foolishness will not depart from him.”
Solution: There are two significant differences in these passages. First, one is speaking of a child, who is still teachable. The other is referring to an adult who is beyond hope. Second, the correctable foolishness is only waywardness, whereas the incorrigible foolishness is beyond hope.