John Lemmon became interested in modal logic when Arthur Prior visited Oxford University in 1956, returning for twelve months after having given the John Locke Lectures, and leading a small group including, besides Lemmon, Peter Geach and Ivo Thomas (Copeland 2004).
John Lemmon became interested in modal logic when Arthur Prior visited Oxford University in 1956 to give the John Locke lectures, later published as his "Time and Modality" (Prior 1957). Prior returned for twelve months soon after, to lead a small group including Lemmon, Peter Geach and Ivo Thomas (Copeland 2004).