Nicolai Hartmann's Possibility and Actuality is a landmark work of modal analysis that describes the logical relations between possibility, actuality, and necessity. It deals with such questions as: How do we know that something is really possible? Is the possible only the actual? Is the actual only the possible? What is the difference between ideal and real possibility?Hartmann reviews the history of philosophical concepts of possibility and necessity, from ancient Megarian philosophy to Aristotle, to Medieval Scholasticism, to Leibniz, Kant, and Hegel. This German-to-English translation enables readers to gain new and fresh insight into Hartmann's important contributions to ontology and the metaphysics of modality.