Can Silence Be a Lie Without a False Statement?

Under the traditional definition, lying usually requires someone to make a statement they believe to be false and to intend another person to believe it. If nothing is said, the statement condition is absent. Silence therefore often does not count as a lie in the strict sense. That does not make it morally innocent, because deception is broader than lying.

Suppose a seller knows that a used car’s brakes sometimes fail. The buyer asks, “Are there any serious problems I should know about?” The seller replies only that the engine has always been reliable, then stops. The claim about the engine may be entirely true, yet it is deliberately used to produce the false impression that there is no serious problem. The wrong lies not only in leaving a fact unsaid, but in exploiting the reasonable expectation created by the question and the seller’s responsibility to disclose a major safety risk.

This does not make every omission deceptive. People need not surrender all privacy to anyone who asks, and conversation always selects information. My judgement is that we should separate definition from moral assessment. Whether silence is a lie depends on whether, in context, it functions as a statement. Whether it is deceptive depends on an intention to create a false understanding, a duty to disclose, and the other person’s right to the information needed for a decision. Someone can undermine honest judgement without uttering a single false sentence.

https://plato.stanford.edu/entries/lying-definition/