On Lukasiewicz's Four-Valued Modal Logic

à Lukasiewicz’s four-valued modal logic is surveyed and analyzed, together with à Lukasiewicz’s motivations to develop it. A faithful interpretation of it into classical (non-modal) two-valued logic is presented, and some consequences are drawn concerning its classification and its algebraic behaviour. Some counter-intuitive aspects of this logic are discussed under the light of the presented results, à Lukasiewicz’s own texts, and related literature.