  In “Is truth only eternal or both eternal and without a beginning?” (1913) he argues for timeless bivalence against Kotarbiński’s view that future contingent propositions lack a determinate truth-value. This paper convinced Kotarbiński he had been in error. The exchange is notable for showing that the discussion of the logical status of future contingent propositions, which inspired Łukasiewicz to invent many-valued logic a few years later, was already under way in Lwów before the First World War.