This very readable introductory logic text covers formal and informal logic. The book combines rigor with relevance, since it uses the strict tools of logic to clarify real arguments from philosophy and everyday life. The innovative proof system uses simpler rules and an automatic proof strategy, and generates refutations for invalid arguments. There's an accompanying interactive computer program (LogiCola, with versions for Windows, DOS, and Macintosh) that randomly generates problems, provides feedback on answers, and keeps homework scores.