FROM CH. 9 CHACHAM PESI:
The opposite of Chachma, wisdom, in Mishlei is Ivellet, lack of wisdom, lack of knowledge. We will learn about Ivellet in Chapter 14, God Willing. So the opposite of having wisdom is "not having wisdom" -- not lack of intelligence, of IQ, of brains, but lack of knowledge, lack of information and the resulting inevitable, dismal failure.
Why is someone lacking knowledge? Lacking information? There can be many characteristics that lead to this sad state -- they are described as K'sil, Eh-vil, Pesi, Leitz, and Ba'ar throughout Mishlei. (Ksil will be learned about more in Chapter 17; Evil in Chapter 14, and Pesi I this chapter.)
Each describes a different personality or habit of mind and deed that results in lack of wisdom.
All these types of "fool" -- and "fool" is really the wrong word here -- all these uneducated or unenlightened people are not doomed to fail. They have no inherent lack of IQ.
The failing of any Fool, a person without wisdom, is that they have failed to seek wisdom. When faced with a problem to solve, when taking on a new role or responsibility in private life -- getting married, having children, making a career path decision -- or in public life -- building a communal committee, teaching others, social activism -- we need to first check in with wisdom!
RSRH pp 52-53
A Ksil will have had opportunities to gain knowledge. Having disdained them, however, and still disdaining them because he overestimates man's intelligence inn general, and his own in particular, in foolish conceit he allows himself to form opinions and hold on to them by sheer force, never heeding objections from a higher source, not even from the Highest One.
The Ksil may possess a good mind. He may have some education. However, he is so pleased with his own mental faculties and his learning that he is convinced of the absolute infallibility of his own views. He doesn't think he needs any further input from anyone.
An intelligent, educated person could recognize the limits of his knowledge -- know what he knows, and know what he doesn't know. He can also handle the truth that nobody is perfect, and he will sometimes make some mistakes. But the Ksil never seeks to know more, because he is sure there is no more to know.
Watching a Ksil talk can be embarrassing. He knows how to run the country, he knows better than the doctors, he knows better than the rabbi, he knows exactly what Tesla or Apple or Google should be doing if they want to be successful.
He is so full of his own vain pride that there is no room for any new ideas.
If you come across a person who is sure he is a wise man -- who has already signed his own Chacham-certificate -- you can be sure that his arrogance testifies to his lack of wisdom. Whatever he has learned, it hasn't been wisdom.
So, wisdom bids such arrogant fools, who consider themselves so wise, "Havinnu Lev!" first of all, try to gain some insight into your own capacity for understanding, before you grant unlimited confidence to your own intelligence and to human intelligence in general; before you form an authoritative opinion about things and matters; before you spurn any superior advice. Get to know your "heart", the narrow range of its understanding, and the impact that sensual desires have upon it. Only then can you become open, accessible to the Divine wisdom.
Appreciate how much is needed to grasp the truth correctly, to know what is right and wrong. Appreciate that there are experts, people who have greater wisdom and deeper understanding, who might share that with you.
It's really worth noting that as with the Pesi in Ch. 7, awareness and self-awareness are the first step to acquiring wisdom.
(א) ט֤וֹב פַּ֣ת חֲ֭רֵבָה וְשַׁלְוָה־בָ֑הּ מִ֝בַּ֗יִת מָלֵ֥א זִבְחֵי־רִֽיב׃
(1) Better a dry slice of bread with tranquility, Than a house full of celebrations that are contentious.
(10) A threatening roar frightens an understanding person More than a hundred blows falling on a fool.
(יב) פָּג֬וֹשׁ דֹּ֣ב שַׁכּ֣וּל בְּאִ֑ישׁ וְאַל־כְּ֝סִ֗יל בְּאִוַּלְתּֽוֹ׃
(12) Sooner be confronted by a she-bear bereaved of her cubs, Than by an arrogant fool in his foolishness.
(יג) מֵשִׁ֣יב רָ֭עָה תַּ֣חַת טוֹבָ֑ה לֹא־[תָמ֥וּשׁ] (תמיש) רָ֝עָ֗ה מִבֵּיתֽוֹ׃
(טו) מַצְדִּ֣יק רָ֭שָׁע וּמַרְשִׁ֣יעַ צַדִּ֑יק תּוֹעֲבַ֥ת יְ֝הֹוָ֗ה גַּם־שְׁנֵיהֶֽם׃
(טז) לָמָּה־זֶּ֣ה מְחִ֣יר בְּיַד־כְּסִ֑יל לִקְנ֖וֹת חׇכְמָ֣ה וְלֶב־אָֽיִן׃
(13) If one repays good with evil, evil will not depart from his house.
(15) Justifying an evildoer and condemning a righteous person -- both are disgusting to God.
(16) Why is there money in the hand of a fool To purchase wisdom, although he has no understanding heart?
(21) One who begets a fool does so to one’s sorrow; The father of a degraded person will not rejoice.
(24) Wisdom lies before an understanding person ; but The eyes of the fool are at the ends of the earth.
The contrast between the Chacham, the wise person, and the Foolish person is a contrast between ability of mind, yes, but also a contrast of improvement of mind. And whereas the ability of your mind is not under your control -- the scope of a person's intellect being determined by God -- how much you IMPROVE the mind you have is your choice, it's up to you.