Two sides of a truth. To "answer a fool according to his folly" is in Proverbs 26:4 to bandy words with him, to descend to his level of coarse anger and vile abuse; in Proverbs 26:5 it is to say the right word at the right time, to expose his unwisdom and untruth to others and to himself, not by a teaching beyond his reach, but by words that he is just able to apprehend. The apparent contradiction between the two verses led some of the rabbis to question the canonical authority of this book. The Pythagoreans had maxims expressing a truth in precepts seemingly contradictory.

Answer not a fool - On this and the following verse Bishop Warburton, who has written well on many things, and very indifferently on the doctrine of grace, has written with force and perspicuity: "Had this advice been given simply, and without circumstance, to answer the fool, and not to answer him, one who had reverence for the text would satisfy himself in supposing that the different directions referred to the doing a thing in and out of season;
1. The reasons given why a fool should not be answered according to his folly, is, "lest he (the answerer) should be like unto him."
2. The reason given why the fool should be answered according to his folly, is, "lest he (the fool) should be wise in his own conceit."
1. "The cause assigned for forbidding to answer, therefore, plainly insinuates that the defender of religion should not imitate the insulter of it in his modes of disputation, which may be comprised in sophistry, buffoonery, and scurrility.
2. "The cause assigned for directing to answer, as plainly intimates that the sage should address himself to confute the fool upon his own false principles, by showing that they lead to conclusions very wide from, very opposite to, those impieties he would deduce from them. If any thing can allay the fool's vanity, and prevent his being wise in his own conceit, it must be the dishonor of having his own principles turned against himself, and shown to be destructive of his own conclusions." - Treatise on Grace. Preface.

Answer not a fool (a) according to his folly, lest thou also be like him.
(a) Consent not to him in his doings.

Answer not a fool according to his folly,.... Sometimes a fool, or wicked man, is not to be answered at all; as the ministers of Hezekiah answered not a word to Rabshakeh; nor Jeremiah the prophet to Hananiah; nor Christ to the Scribes and Pharisees; and when an answer is returned, it should not be in his foolish way and manner, rendering evil for evil, and railing for railing, in the same virulent, lying, calumniating, and reproachful language;
lest thou also be like unto him; lest thou also, who art a man of understanding and sense, and hast passed for one among men, come under the same imputation, and be reckoned a fool like him.

We are to fit our remarks to the man, and address them to his conscience, so as may best end the debate.

Answer not--that is, approvingly by like folly.

4 Answer not the fool according to his folly,
Lest thou thyself also become like unto him.
After, or according to his folly, is here equivalent to recognising the foolish supposition and the foolish object of his question, and thereupon considering it, as if, e.g., he asked why the ignorant man was happier than the man who had much knowledge, or how one may acquire the art of making gold; for "a fool can ask more than ten wise men can answer." He who recognises such questions as justifiable, and thus sanctions them, places himself on an equality with the fool, and easily himself becomes one. The proverb that follows affirms apparently the direct contrary:

According - So as to imitate his folly, by passionate or reproachful speeches.