What does Proverbs 17:12 mean?

Those who live in regions where bears are common know how dangerous they can be. Few situations are as dangerous as coming between a mother bear and her offspring. At the same time, that danger is usually avoidable. Solomon points out here that encountering fools is actually more dangerous. In the context of the book of Proverbs, "wisdom" is defined as an application of God's truth (Proverbs 1:7). Foolish people are those who reject God's truth and goodness (Psalm 14:1; Proverbs 14:16). That makes them unpredictable and capable of far worse mayhem than any mother bear.

Individual fools, or those without power and influence, are dangerous enough. Fools with power can leave lasting scars on history. In the days of the New Testament, the ruling Herods were vicious, violent fools. Herod the Great ordered the assassination of all the male children in Bethlehem and its vicinity, hoping to kill the infant Jesus (Matthew 2:14–16). Another Herod killed James the brother of John, and when he saw that it pleased the Jews, he apprehended Peter and intended to kill him too (Acts 12:1–3).