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About the Third Edition

In the third edition, we have reorganized the material in response to feedback from instructors and students. The goal has been to produce a more modular text, so that, for example, instructors who wish to proceed to truth tables before proofs no longer have to break in the middle of chapter 1, but can jump past chapter 2 (where the material on sentential proofs is now confined) and proceed directly to the new chapter 3 before returning to teach the material in the second chapter. In the second part of the book we have similarly divided the material from the two original chapters into three new chapters 4–6, maintaining the same three-part division between the language, the rules of proof, and the semantic treatment of predicate logic via models.

We have also extracted all the material on identity into a seventh chapter. This material was originally added in the second edition where it was distributed through the third and fourth chapters of that edition, but many instructors who did not wish to cover the toqpic found it distracting to have to work around that material when teaching basic predicate logic. We have maintained the tripartite language/proof/semantics structure within the three sections of the new chapter, again allowing some flexibility in the way the material is approached. We hope that these changes allow instructors to choose a path through the material that will maximize their students’ success.

Lastly, we have made some changes in the Exercises to try to support students moving from easier to harder problems as they work through an exercise. We heard from both instructors and students that encountering a very hard problem at the beginning of an exercise often proved discouraging, and that this was often compounded when a student turned to the appendix for the answer, only to find a proof spanning more than a page. We don’t promise to have made the sequencing perfect, but we do hope that it is better, and that after nearly three decades in print, this book continues to fulfill our original intent of a concise, rigorous, yet accessible introduction to symbolic logic.