  Arthur Prior (1914–1969) undertook pioneering work in intensional logic at a time when modality and intensional concepts in general were under attack. He invented tense logic and was principal theoretician of the movement to apply modal syntax to the formalisation of a wide variety of phenomena. Prior and Carew Meredith devised a version of the possible worlds semantics several years before Saul Kripke published his first paper on the topic. An iconoclast and a resourceful innovator, Prior inspired many to undertake work in intensional logic.