Stanford University
Stanford Encyclopedia of Philosophy: Modal Logic
Explains modal logic by means of logical notation. Somewhat difficult for a non-specialist to appreciate. However, the introductory section does provide a general definition of "modal logic."
Stanford University
Stanford Encyclopedia of Phil.: Ontological Arguments
Overview from the Stanford Encyclopedia of Philosophy of the structure and history of ontological arguments for the existence of God. Lists the major attempts (and includes extensive bibliography for them), then describes the various...
Stanford University
Relevance Logic/stanford Encyclopedia of Philosophy
Discusses the topic of relevance (or relevant) logics. Presents the theory and applications of relevance logic, which attempts to resolve "fallacies of relevance."
Stanford University
Temporal Logic/stanford Encyclopedia of Philosophy
Discusses the temporal logic of Arthur Prior, a type of modal logic. After technical definitions, author addresses related philosophical issues. Also summarizes applications in natural language, computer science, and artificial...