NET
18 Guard against self-deception, each of you. If someone among you thinks he is wise in this age, let him become foolish so that he can become wise.
Darby
18 Let no one deceive himself: if any one thinks himself to be wise among you in this world, let him become foolish, that he may be wise.
KJV
18 Let no man deceive himself. If any man among you seemeth to be wise in this world, let him become a fool, that he may be wise.