Nicolai Hartmann's Possibility and Actuality is the second volume of a four-part investigation of ontology. 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?

This groundbreaking work of modal analysis describes the logical relations between possibility, actuality, and necessity, and it provides insight into the relations between modes of knowledge and modes of being.

Hartmann reviews the history of...