First-Order Modal Logic

The book provides an in-depth exploration of first-order modal logic, integrating new insights and revisions since its original 1998 publication. It employs a threefold approach using possible world models, tableau proof systems, and philosophical discourse. Key topics include quantification, the distinction between actualist and possibilist quantifiers, and the treatment of existence, non-rigid constants, and predicate abstraction. The authors also address significant philosophical issues, drawing on Fregean and Russellian theories to clarify complex concepts like nonexistence and definite descriptions.