First-Order Modal Logic : Springer : 9783031407130 : 303140713X : 19 Oct 2023 : This revised edition of the highly recommended book "First-Order Modal Logic", originally published in 1998, contains both new and modified chapters reflecting the latest scientific developments. Fitting and Mendelsohn present a thorough treatment of first-order modal logic, together with some propositional background. They adopt throughout a threefold approach. Semantically, they use possible world models; the formal proof machinery is tableaus; and full philosophical discussions are provided of the way that technical developments bear on well-known philosophical problems. The book covers quantification itself, including the difference between actualist and possibilist quantifiers; equality, leading to a treatment of Frege's morning star/evening star puzzle; the notion of existence and the logical problems surrounding it; non-rigid constants and function symbols; predicate abstraction, which abstracts a pr