1: How to Reason Logically

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Bradley H. Dowden
California State University Sacramento

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The goal of this book is to improve your logical-reasoning skills. These skills are also called "critical thinking skills." They are a complex weave of abilities that help you get someone's point, generate reasons for your own point, evaluate the reasons given by others, decide what or what not to do, decide what information to accept or reject, explain a complicated idea, apply conscious quality control as you think, and resist propaganda. Your most important critical thinking skill is your skill at making judgments─not snap judgments that occur in the blink of an eye, but those that require careful reasoning.

You are not reasoning logically if, when you want a gorilla suit for a Halloween party, the first thing you do is search for the word "Gorilla" in the telephone book, and the problem here is not that you used a telephone book instead of the Internet.

High-quality reasoning is called logical reasoning or critical thinking. Logical reasoning skills can be learned and improved. It is not a case of "Either you're naturally good at it or you’re not." Rather, nearly everyone is capable of reasoning well, and everyone is capable of improvement. The opposite of logical reasoning is uncritical thinking, examples of which are fuzzy thinking, believing what somebody says simply because they raise their voice, and narrowly thinking about a problem without bringing in the most relevant information.

This first chapter explains what it means to be logical—to reason logically or critically. It demonstrates the usefulness of logical reasoning as a means of making more effective decisions about your own life—decisions about what to believe and decisions about what to do. The chapter begins a systematic program of study of all the major topics regarding logical reasoning. Along the way, the book focuses on developing the following five skills: (1) writing logically, (2) detecting inconsistency and lack of clarity in a group of sentences, (3) spotting issues and arguments, (4) detecting and avoiding fallacies (reasoning errors), and (5) generating and improving arguments and explanations. These skills will be taught here independent of subject matter. This book is not about what you ought to believe about some subject such as politics, religion, sports or business.

Although many scientific studies of decision-making have shown that people tend to sift sources of information looking to reinforce existing views rather than to accept the view that is backed up with the better argument, your book is designed to combat this tendency.