The wisdom of the prudent is to discern his way, but the folly of fools is deceiving.
Proverbs 14:8

True wisdom makes a path clearer. Frequently, all you need is to understand right from wrong according to God's standards, and decisions will make themselves.

The wisdom of man is here called "folly of fools" because it ignores the source of all wisdom. It might sound wise, full of nuance and subtlety, but it will only lead you to death.