Proof by contradiction in sentence and text

The paper is devoted to the proof by contradiction (PbC), its logic, pragmatics, and means of expression in Russian. It is stated that the main communicative-pragmatic function of PbC is refutation, realized in two logical-argumentational varieties: No-refutation and Yes-refutation, when one refutes an opponent’s positive or negative statement, respectively. PbC also executes a cognitive function, not in a debate, but rather just in the course of justification of a hypothesis. Syntactic exponents of PbC are irreal conditional sentences, quasi-conditional constructions with a rhetorical complication, and sentences of alternative motivation. Derivation of all those structures is performed, inter alia, through marking the apodosis as a rhetorical question; specifics of the latter is determined by propositional semantics of the structures in question.