Phoebe Ellsworth was facing a difficult decision. As ayoung professor at Yale University, she had received a tempting job offer from the University of Michigan. Should she stay or should she go?
Following the advice of many experts in decision making, she took two large sheets of paper—one for each university—and listed their positives and negatives, assigned numbers to each item according to how important it was to her, and then added up those numbers. But, with the numbers neatly summed, Ellsworth discov-ered she wasn’t content with the result. “It’s not coming out right!” she exclaimed to fellow psychologist Robert Zajonc.
In the end, she went with her gut and made her decision based primarily on her feelings about the choice and not on her calculations. The decision has worked out well for her, and, three decades later, she’s a distinguished professor of law and psy-chology at Michigan—where she studies, among many things, how emotions sway people’s decisions about such crucial matters as murder trials. Meanwhile, Zajonc continued to research the interplay between feeling and thinking, and ended up arguing that cases like Ellsworth’s are relatively common, so that, ironically, people rarely use only their minds to “make up their minds.”
Zajonc’s claim suggests that people are less “rational” than we believe we are—even when we’re trying to be thoughtful and careful, and even when we’re thinking about highly consequential issues. And, in fact, many other lines of evidence—and many other psychologists—raise their own questions about human rationality. For example, studies suggest that we tend to pay special attention to information that confirms our hunches and hopes and ignore (or overrule) evidence that might challenge our beliefs. We flip-flop in our preferences—even when making important decisions—influenced by trivial changes in how our options are described. We rely on reasoning “shortcuts,” even when drawing life-altering conclusions, apparently making our conclusions using strategies that are efficient but prone to error. And we’re easily persuaded by “man who” stories—“What do you mean cigarettes cause lung cancer? I know a man who smokes two packs a day, and he’s perfectly healthy”—even though, with a moment’s reflection, we see the illogic in this.
What should we make of these findings? Is it possible that humans—even smart, well-educated humans, doing their best to think carefully and well—are, in truth, often irrational? And if so, what does this imply about us? Are our heads filled with false beliefs—about ourselves, our friends, and our world? Will we make decisions that fail to bring us happiness? We’ll tackle all these questions later, asking how people think, and also how well. We’ll focus first on the content of thought and theways that different types of ideas are represented in the mind. We’ll then turn to the processes of thought, with our main focus on what psychologists call directed thinking—the mental activities we use to achieve goals. Specifically, we’ll look at theprocesses used in interpreting information, judging the truth of an assertion, solving problems, and weighing the costs and benefits of a decision.