Proverbs 26 has this seemingly contradictory pair of admonitions, back to back:
Answer not a fool according to his folly,
lest you be like him yourself.
Answer a fool according to his folly,
lest he be wise in his own eyes.
How can we follow two instructions that seem to be so directly counter to one another? By understanding that the shortcomings of the English language do not nullify the value of God's word.
First, let's look at some surrounding context in Proverbs. What defines a fool's folly?
There are plenty of passages in the chapters immediately preceding that define wisdom:
He who loves purity of heart, and whose speech is gracious, will have the king as his friend. The eyes of the LORD keep watch over knowledge, but he overthrows the words of the traitor. (Proverbs 22:11-12 ESV) Make no friendship with a man given to anger, nor go with a wrathful man, lest you learn his ways and entangle yourself in a snare. (Proverbs 22:24-25 ESV)
A word fitly spoken
is like apples of gold in a setting of silver.
Like a gold ring or an ornament of gold
is a wise reprover to a listening ear.
Like the cold of snow in the time of harvest
is a faithful messenger to those who send him;
he refreshes the soul of his masters.
Like clouds and wind without rain
is a man who boasts of a gift he does not give.
With patience a ruler may be persuaded,
and a soft tongue will break a bone.
We see that wisdom speaks the truth with grace, trusting that the Lord will vindicate. Wisdom does not follow the ways of a wrathful man, entangling itself in a snare. So this explains the first exhortation, that we answer not a fool according to his folly: that is, don't meet foolishness with foolishness. The second exhortation is unpacked in verses that follow our perplexing passage:
Like a lame man's legs, which hang useless,
is a proverb in the mouth of fools.
Like one who binds the stone in the sling
is one who gives honor to a fool.
Like a thorn that goes up into the hand of a drunkard
is a proverb in the mouth of fools.
Like an archer who wounds everyone
is one who hires a passing fool or drunkard.
Like a dog that returns to his vomit
is a fool who repeats his folly.
Do you see a man who is wise in his own eyes?
There is more hope for a fool than for him.
Better is open rebuke
than hidden love.
Faithful are the wounds of a friend;
profuse are the kisses of an enemy.
Iron sharpens iron,
and one man sharpens another.
The fate of a fool allowed to continue in foolishness is a dire one; he becomes useless, a "thorn" to others, and a wound to everyone. To allow a foolish man to remain wise in his own eyes is to condemn him to this end. If we care about this person -- if we love him as Christ commands -- are more faithful and more loving to offer rebuke when it's needed to save him from such a disaster. We're commanded to love our neighbor as ourselves, and it's precisely that command that dictates that we help guide back a neighbor turned towards a terrible end. But that love must also form and inform the way we do so -- not with retaliation or mockery, but with the grace we've been given.