We all reason about what we ought to do, what should be, and what is permissible, but neither Standard Deontic Logic (SDL) nor its more recent variants adequately represent the principles of our deontic reasoning. In this groundbreaking new work, author James Forrester first explores the shortcomings of standard deontic systems, and concludes that we need a new type of deontic logic; in the second part of the book, he presents a new deontic logic and semantics that fit our deontic reasoning better than standard systems. Finally, in a third section, Forrester sketches some original implications of his new deontic logic for practical reasoning. This book will be of interest to all philosophers, especially those with an interest in questions of moral and practical reasoning.

This work represents an attempt to show that standard systems of deontic logic (taken as attempts to codify normal deontic reasoning) run into a number of difficulties. It also presents a new system of deontic logic and argues that it is free from the shortcomings of standard systems.