Lying

Lying is deliberately communicating a statement one believes to be false. It is distinct from error because the speaker intends to deceive.

Deception: Deception is intentionally causing another person to form or retain a false belief. Lying is one way to deceive, though deception can also occur without false statements.
Honesty: Honesty is the practice of communicating sincerely and avoiding intentional deception. Honesty is the direct ethical opposite of deliberately asserting what one believes false.
Perjury: Perjury is the criminal offense of knowingly making a material false statement under oath. It is a legally defined form of lying with specific requirements and penalties.
Kantian ethics: Kantian ethics is a moral theory grounded in rational duty and principles that apply universally. Kant's strict opposition to lying makes it a central test of duty-based morality.
Murderer at the door: The murderer-at-the-door case asks whether someone should lie to a would-be murderer seeking a victim's location. It tests whether a duty not to lie survives an urgent threat to another person.
Assertion: An assertion presents a proposition as true and makes its speaker accountable for it. A lie typically uses assertion to present a believed-false proposition as true.
Error: An error is a mistaken belief, judgment, or statement that need not involve deceptive intent. A false statement caused by sincere mistake is not a lie under the given definition.
White lie: A white lie is a minor falsehood told to avoid hurting someone or to smooth social interaction. It illustrates cases where a lie may be judged by its benign purpose and limited harm.
Consequentialism: Consequentialism judges actions by the value of their outcomes. It can permit a lie when expected benefits outweigh harms.
On a Supposed Right to Lie from Philanthropy: Immanuel Kant's 1797 essay argues against a supposed right to lie, even from benevolent motives. Kant directly addresses whether a lie can be justified to protect someone.

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