Unmöglichkeit

Unmöglichkeit is a German noun meaning the state or quality of being impossible. It derives from un- (negation) and möglich (possible), with the suffix -keit forming a noun for a property. The term is used in everyday language as well as in fields such as philosophy, logic, and law.

In ordinary speech unmöglich describes something that cannot be done or cannot occur. In philosophy and logic the term denotes propositions or states that cannot be true under any interpretation or circumstances. Philosophical distinctions are made between logical impossibility (contradictions such as a square circle) and physical impossibility (contrary to natural law). The concept also appears in discussions of possibility in modal logic and metaphysics.

In legal contexts, Unmöglichkeit der Leistung refers to the impossibility of performing a contractual obligation. German civil law distinguishes objective impossibility (impossible for anyone) from subjective or personal impossibility (only the debtor cannot perform). When performance is objectively impossible, the obligation is generally discharged; the creditor cannot demand performance, and liability for breach is typically excluded unless caused by fault or exceptional circumstances. Temporary or partial impossibility may suspend or modify duties until the situation changes. The concept matters for contract rescission, price adjustments, and risk allocation in commercial practice.