There is a "fool" in each and everyone of us. A "fool" (or "jerk") is one who willingly and consistently disregards what is right. It's a matter of degree or severity (i.e. first-degree, second-degree etc.). When this "fool" within is not adequately treated, problems, hurts, and wounds inevitably happen in life.
Proverbs 26 cites several characteristics of a fool.
1. Fools can not handle honor (e.g. boasts about immoral and irresponsible behavior), v. 1.
2. Fools would not respond to discipline, v. 3.
3. Fools don't connect behavior with consequences, vv, 4-5.
4. Fools are not trustworthy, v. 6.
5. Fools waste wisdom (e.g. may accept wrong, but chooses to still do it), v. 9.
6. Fools use wisdom as a weapon (e.g. give them wise principle and they'll turn it around to destroy,
manipulate, control, or use it for self-centered reason), v. 10.
7. Fools are destructive (wreak havoc wherever you put them), v. 10.
8. Fools return to the same nauseating vomit, v. 11.
9. Fools are self-deceived, v. 12.