A draft textbook by Theodore Sider aimed at philsophy graduate students that while not as technical as computer scientists are used to, may be of interest due to the explicit discussion of extensions (e.g., modal operators), deviations (e.g., multi-valued logic) and variations (such as the Sheffer Stroke) on basic propositional logic.

The book includes chapters on counterfactuals and two-dimensional modal logic that may include material new to PLT wonks.