As the title suggests, Lehrer explores the processes of making decisions, calling on a wide variety of experiments, data, and theory from economics, neurobiology, and psychology. He also uses case studies of particular decisions (e.g., landing a plane in an emergency, escaping a forest fire, purchasing items in a grocery store, and so on) to give the data a human face, so to speak.

We have a variety of mental processes that are useful and necessary for making good decisions; using the right mental processes in any given decision-making situation is the challenge. The cognitive capacity is limited (“seven plus or minus two”) and can be overwhelmed by data, but is (of course) essential to good decision-making if used in appropriate situations and in appropriate ways. The surprising finding is that unconscious analysis – manifested through the emotions – is a surprisingly robust tool, if used in appropriate situations and appropriate ways. Lehrer encourages us to embrace uncertainty and to attend to our thinking processes, being aware of the shortcomings and failings of the various aspects of native mental processes.

Although it is not the main point of the book, How We Decide also makes me reconsider the meaning of “rational,” especially if the idea of rationality is paired as emotion’s opposite. Lehrer makes a good case for our decision-making process as a complex and balanced combination of rational, cognitive, emotional, and unconscious.