Chapter 1 now focuses almost exclusively on deductive logic.

Chapter 2 presents and discusses the formal syntax for the language SL before turning to symbolizations. Chapter 4 presents all of the truth-tree rules in the first section, and Chapter 5 does the same for the derivation rules of SD.

The discussion of the completeness proof in Chapter 6 has been rewritten to make the flow of the proof more apparent.

Like Chapter 2, Chapter 7 now presents the formal syntax of PL before discussing symbolization, and the Aristotelian square of opposition figures less prominently than it did in previous editions.

Chapter 8 begins with a presentation of the formal semantics for predicate logic, discussing the formal semantics at greater length and with more examples. (However, those who want to skip most of the formal semantics can do so—we indicate this in the middle of Section 8.1, and we continue to display interpretations in the style of symbolization keys in most of the remainder of the chapter.) All interpretations presented in Chapter 8, except for some exercises for the first section, now use the set of positive integers as the UD.

Chapter 9 recovers only extensions of predicates, rather than English readings of those predicates, from completed open branches of truth-trees. Finally, we have added an appendix with some facts about the positive integers; this can serve as a refresher for students as they work through symbolization in Chapter 7 and the construction of interpretations in Chapter 8.