There’s an ancient view, still widely held, that what makes human beings special—what distinguishes us from the “beasts of the field”—is that we are rational. What does rationality consist in? That’s a vexed question, but one possible response goes roughly like this: we manifest our rationality by engaging in activities that involve reasoning—making claims and backing them up with reasons, acting in accord with reasons and beliefs, drawing inferences from available evidence, and so on.
This reasoning activity can be done well and it can be done badly—it can be done correctly or incorrectly. Logic is the discipline that aims to distinguish good reasoning from bad.
Since reasoning is central to all fields of study—indeed, since it’s arguably central to being human—the tools developed in logic are universally applicable. Anyone can benefit from studying logic by becoming a more self-aware, skillful reasoner.
This covers a variety of topics at an introductory level. Chapter One introduces basic notions, such as arguments and explanations, validity and soundness, deductive and inductive reasoning; it also covers basic analytical techniques, such as distinguishing premises from conclusions and diagramming arguments. Chapter Two discusses informal logical fallacies. Chapters Three and Four concern deductive logic, introducing the basics of Aristotelian and Sentential Logic, respectively. Chapters Five and Six concern inductive logic. Chapter Five deals with analogical and causal reasoning, including a discussion of Mill’s Methods. Chapter Six covers basic probability calculations, Bayesian inference, fundamental statistical concepts and techniques, and common statistical fallacies.
The text is suitable for a one-semester introductory logic or “critical thinking” course. The emphasis is on formal techniques and problem solving rather than analytical writing, though exercises of the latter sort could easily be incorporated.
A note on tone, style, and content. This book is written by an American teacher whose intended audience is American undergraduates; it is based on my lectures, developed over many years. Like the lectures, it assumes that some members of the intended audience lack an antecedent interest in the subject and may have trouble developing and maintaining enthusiasm to study it. It tries to compensate for this by adopting a casual style, using first- and second-person constructions, and by shamelessly trafficking in cultural references, lame jokes, and examples involving American current events. The result is a logic textbook with a somewhat unusual tone and a sometimes narrow cultural perspective. Neither familiarity with the relevant cultural references, nor amusement at the lame jokes, is a prerequisite for understanding the material, but I thought it prudent to offer an apologia at the outset. Caveat lector.
An acknowledgment of debts. The following books have influenced my teaching, and hence the present work: Virginia Klenk’s Understanding Symbolic Logic, John Norton’s How Science Works, Ian Hacking’s Introduction to Probability and Inductive Logic, Darrell Huff’s How to Lie with Statistics, and Irving Copi and Carl Cohen’s Introduction to Logic. The influence of those last two books is particularly profound, as I note throughout this text. I am indebted to all my logic teachers over the years: Kurt Mosser, Michael Liston, Mark Kaplan, Richard Tierney, Steve Leeds, Joan Weiner, Ken Manders, Mark Wilson, and Nuel Belnap. Thanks to J.S. Holbrook for sending me examples of fallacies. For extensive logistical support, I’m indebted to Kristin Miller Woodward; I also thank her for arranging financial support through the UW-Milwaukee Library and Center for Excellence in Teaching and Learning, who have undertaken a project to encourage the development and adoption of open textbooks. My logic students over the years also deserve acknowledgment, especially those who have recently served as guinea pigs, learning from earlier drafts of this book. Without student feedback, there would be no book. Finally, and most importantly, I could not have completed this project without my wife Maggie’s constant support and forbearance.