Honesty is the best policy; but he who acts on this principle is not an honest man.

The deliberately paradoxical saying distrusts honesty practiced solely because it is advantageous. Here, “policy” means expedient self-interest: if truthfulness is chosen as a profitable tactic rather than from sincere regard for truth, the speaker treats that calculation as evidence that the person lacks genuine honesty.

It separates outwardly honest conduct from honest character and criticizes strategic truthfulness, not honesty itself. A person may tell the truth whenever it serves their interests, yet remain ready to deceive when it does not; principled integrity requires more than a convenient rule of self-interest.

Use this as an ironic criticism of someone who advertises honesty chiefly as a shrewd strategy. It suits discussions of motive and integrity, especially where apparently truthful behavior may be driven by calculation rather than conviction.