Abstract
Investigates the contents of Schopenhauer's first book On the Fourfold Root of the Principle of Sufficient Reason. This is devoted to the nature of explanation. It concludes that all events in the empirical world fall under one or more of four forms of explanation: scientific, mathematical, logical, and motivational. Since all meaningful empirical concepts are derived from experience, and no valid deductive argument can add to the content of its own premises, the only fully satisfactory empirical knowledge is provided by direct perception.