What does Proverbs 14:15 mean?

Critics who claim the Bible promotes "blind faith" prove only that they've never bothered to read it. This is one of many teachings in Scripture about the need for cautious, reasonable skepticism (Proverbs 14:18; Acts 17:11; 2 Corinthians 13:5; 1 John 4:1). Proverbs 14:15 contrasts the foolishness of gullibility with the wisdom of thoughtfulness (Matthew 10:16). This is a slightly different emphasis than the following verses (Proverbs 14:16–17) which warn against being too quick to judge or act.

The members of the Galatian churches were gullible. Instead of clinging to the gospel Paul had delivered to them, they believed what false teachers told them. The false teachers preached a false gospel that required circumcision and conforming to the law of Moses for salvation. Paul called the Galatians foolish and bewitched because they had begun in the Spirit but had succumbed to the belief that the works of the law were necessary for salvation (Galatians 3:1–3). He urges them in Galatians 1:8–9 to consider accursed every teacher that preaches a false gospel. Today, as in Paul's day, it is wise to weigh carefully what we see and hear before accepting a teaching. The Scriptures are our only perfectly reliable guide for our path through life (Psalm 119:105; 2 Timothy 3:15–17).