Your first task is to evaluate whether the evidence is based on accurate research and information (generally reliable) or if it is based on uninformed opinions and personal feelings (usually unreliable). Valid opinions may be informed through research, experience, or specialized expertise in a field. But opinions may also be uninformed, meaning that they are not verifiable through experience or expertise but exist simply because the author wishes to hold them for convenience or because they correspond with his or her own values and beliefs. Simply because evidence is presented to you in a convincing way does not mean it must be accepted as fact.

To illustrate and practice the critical—thinking techniques you will use in evaluating the evidence presented in this book, we will examine two of the articles in the book. One piece, "Twentieth—Century...