The next two proverbs appear at a superficial level to contradict each other since they propose two opposite courses of action, but in fact they present two opposite mistakes that we can make in dealing with the foolish, both of which should be avoided. In any encounter with a fool we have to be aware of these two problems: we must avoid being dragged down to their level, and we must avoid simply letting them get away with their foolishness.
The result of answering the fool according to his folly will be that we become like him. Our strength lies in our righteousness and our separation from evil. If we abandon our integrity, our faithfulness to God, our patience to the end, then like Sampson we become as other men, losing the supernatural strength that the indwelling Spirit gives us, for we grieve him. Then our testimony is worth nothing and any good that we might have done to the fool will be neutralised. We are to be living alongside them, but not imitating. Our normal behaviour will be a reproof to them without constantly having to explicitly rebuke them. We do not laugh at the unclean or questionable jokes they laugh at, or show enthusiasm for the same depraved subjects that they do. This is the negative side of our interaction with the world.