Necessity

Necessity is the condition of being required to achieve an end or avoid a serious harm. What counts as necessary depends on the end, available alternatives, and the harm at stake.

Moral dilemma: A situation in which competing moral requirements make every available choice appear to violate an important value. A necessity claim often arises when avoiding one harm requires causing or permitting another.
Necessity defense: A legal defense claiming that unlawful conduct was needed to prevent a greater imminent harm. It is the direct legal form of a necessity claim.
Sufficient condition: A condition that guarantees a specified outcome whenever it is met. A necessary condition must be present for an outcome but need not guarantee it.
Obligation: A binding requirement to act or refrain from acting under a rule, role, or commitment. Necessity can explain why an obligation applies, but practical need and duty are not identical.
Moral responsibility: The status of being answerable for an action or omission under moral standards. Necessity may reduce blame without making the harmful act harmless.
State of necessity: A circumstance in international law that may preclude a state’s wrongfulness when essential interests face grave and imminent peril. It applies necessity to a state’s breach of an international obligation.
Necessary and sufficient conditions: Conditions that respectively must hold for an outcome and, when combined, guarantee it. Logical necessity is a neighboring sense, distinct from necessity relative to an end.
Permission: A normative status in which an action is allowed but not required. An act may be permitted without being necessary to reach an end or avert harm.
Moral luck: The influence of factors beyond an agent’s control on moral judgment of that agent. Outcomes can change whether an action appears necessary, even when the choice was unchanged.
Self-defense: The use of force to protect oneself or another from an unlawful threat. Unlike necessity, self-defense responds to a wrongful threat posed by another actor.

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