Modal Logic: An Introduction to Its Syntax and SemanticsIn this text, a variety of modal logics at the sentential, first order, and second order levels are developed with clarity, precision and philosophical insight. All of the S1 S5 modal logics of Lewis and Langford, among others, are constructed. A matrix, or many valued semantics, for sentential modal logic is formalized, and an important result that no finite matrix can characterize any of the standard modal logics is proven. Exercises, some of which