  1962 was a significant year for tense logic. As well as Hintikka’s talk in Helsinki, Scott gave a lecture on tense logic in Amsterdam (Hans Kamp, then an undergraduate, was among his audience). Scott’s work on tense logic was one aspect of his study of the semantics of natural language, which he pursued in close collaboration with Richard Montague. Scott was aware of Prior’s work, and was also influenced in his understanding of tense by Reichenbach’s 1947 analysis (the latter was a powerful figure at UCLA until his death in 1953). Prior himself was critical of Reichenbach’s analysis of the tenses, describing it as having been ‘in some ways a hindrance rather than a help to the construction of a logic of tenses’ (Prior 1967a: 13). Scott’s work in tense logic was different in style from Prior’s. He established the completeness and decidability of various axiomatic tense logics, and also showed that the temporal predicate logic of the reals is non-axiomatisable. His work in tense logic is widely cited but remains unpublished. Prior learned of Scott’s work in January 1964, in a letter from Lemmon (who the previous year had left Oxford for Claremont, near Los Angeles).