• Intended for a course for students in philosophy, mathematics, linguistics, or computer science, and excellent for self-study. • Motivation is given for each formal concept and each step in building a formal logic in terms of formalizing reasoning. Summaries are given at important junctures in the book to keep students aware of what they are doing and where they are going. • Criteria of formalization are developed and applied to formalizing ordinary language reasoning in an example-analysis format. • More than 300 worked examples. • More than 500 exercises with answers available on the web.