Impossibility

Impossibility may refer to:

Philosophy and logic

 * Epistemic impossibility, in modal logic a statement that cannot be true, given what we know
 * Subjunctive impossibility, types of statement that cannot be true based on various types of subjunctive modality
 * Logical impossibility, a statement that contains a logical contradiction
 * Impossible world, a concept in philosophical logic

Other uses

 * Impossibility of performance, in contract law an excuse for non-performance of a contract
 * Impossibility defense, a criminal defense for a crime that was legally impossible to commit
 * Proof of impossibility, in mathematics a proof that demonstrates that a particular problem cannot be solved