Proverbs 26:4-5 initially appears to give contradictory advice: "DO NOT ANSWER a fool according to his folly, or you will also be like him. ANSWER a fool according to his folly, that he not be wise in his own eyes." The keys to properly interpreting the apparently conflicting advice are the descriptions qualifying the imperative. The objective in the first case is engaging a fool without stooping to his level, using abusive language, character assassination, deflecting and blame-shifting. The goal should be rather narrowly correcting the fool over the issue in dispute, addressing raw facts without being abusive or judgmental of the fool. Of course the fool might still blow you off, but at least you're not communicating like the fool, according to his folly. And methodically sticking to the issue without being disrespectful is potentially corrective. The fool can no longer easily be right in his own eyes. The real issue then in these verses is how we converse with a fool, who would provoke a response in us that is verbally abusive, and abuse returned discredits whatever wisdom we might provide.
The Foolishness of Fools is Deceit
"Ephesians 4:22 commands Christians to ""lay aside the old self which is being corrupted by the lusts of deceit."" The old idolatrous self pursued desires outside of the parameters of God. Lusts of deceit typically promise immediate gratification but hide costs over the long term, resulting in repetitive satisfaction of seemingly innocuous lusts. Corruption nevertheless sets in. Repetition ossifies lusts, and the old self is practically defined by the lust which is now an habitual practice. The periodic drinker becomes a drunkard, the occasional gossiper an egregious slanderer, the ""recreational user,"" a full blown drug-addict. The costs are now plainly evident, but the fool characteristically doubles down, and rationalizes his slavery. (""I can quit anytime I want, he loudly protests"") The fool originally contracted the lusts of deceit to serve the old self; now lusts are the master and the old self the servant, who has been thoroughly corrupted by the lusts of deceit. The Scriptures address this root of deception: ""The foolishness of fools is deceit."" (Proverbs 14:8) The practice of engaging lusts (foolishness) among fools reinforces self-deception. In any event, the foolishness of fools doesn't instantly leave when saints confess Christ. The episode notes that the old self is presently BEING corrupted by the lusts of deceit. All Christians are in the process of sanctification in which the Holy Spirit helps the believer identify with the new man in Christ, which is ""created in righteousness and holiness of the truth."" (24) This identification founded on TRUTH is the antidote to the DECEIT of fools. Believers then must regularly put on Christ, while they lay aside the old self, making no provision for the flesh in regard to its lusts. (Romans 14:17)