Reflecting fifty years later on his experience in the Israeli army, Kahneman remarks in Thinking, Fast and Slow that it was not unusual in those days for young people to be given big responsibilities. The country itself was only seven years old. “All its institutions were under construction,” he says, “and someone had to build them.” He was lucky to be given this chance to share in the building of a country, and at the same time to achieve an intellectual insight into human nature. He understood that the failure of the old interview system was a special case of a general phenomenon that he called “the illusion of validity.” At this point, he says, “I had discovered my first cognitive illusion.”The deep trust that we all place in our own intuitive judgments is what Kahneman is trying to warn us about. But more importantly, Kahneman explains to us just why our intuitive judgments are so prone to being faulty.
Cognitive illusions are the main theme of his book. A cognitive illusion is a false belief that we intuitively accept as true. The illusion of validity is a false belief in the reliability of our own judgment. The interviewers sincerely believed that they could predict the performance of recruits after talking with them for fifteen minutes. Even after the interviewers had seen the statistical evidence that their belief was an illusion, they still could not help believing it. Kahneman confesses that he himself still experiences the illusion of validity, after fifty years of warning other people against it. He cannot escape the illusion that his own intuitive judgments are trustworthy. _Freeman Dyson
At the end of his book, Kahneman asks the question: What practical benefit can we derive from an understanding of our irrational mental processes? We know that our judgments are heavily biased by inherited illusions, which helped us to survive in a snake-infested jungle but have nothing to do with logic. We also know that, even when we become aware of the bias and the illusions, the illusions do not disappear. What use is it to know that we are deluded, if the knowledge does not dispel the delusions?And then, Freeman Dyson asks us to take Kahneman's insights, and to courageously apply them to farther fields of human endeavour. According to Dyson, Kahneman limited his research to what could be studied experimentally. But of all the broad range of life which humans experience, only a select segment can be studied in that way. Kahneman's insights are thus in need of expansion to other areas of life.
Kahneman answers this question by saying that he hopes to change our behavior by changing our vocabulary. If the names that he invented for various common biases and illusions, “illusion of validity,” “availability bias,” “endowment effect,” and others that I have no space to describe in this review, become part of our everyday vocabulary, then he hopes to see the illusions lose their power to deceive us. If we use these names every day to criticize our friends’ mistaken judgments and to confess our own, then perhaps we will learn to overcome our illusions. Perhaps our children and grandchildren will grow up using the new vocabulary and will automatically correct their congenital biases when making judgments. If this miracle happens, then future generations will owe a big debt to Kahneman for giving them a clearer vision. _Freeman Dyson
Freud and James were artists and not scientists. It is normal for artists who achieve great acclaim during their lifetimes to go into eclipse and become unfashionable after their deaths. Fifty or a hundred years later, they may enjoy a revival of their reputations, and they may then be admitted to the ranks of permanent greatness. Admirers of Freud and James may hope that the time may come when they will stand together with Kahneman as three great explorers of the human psyche, Freud and James as explorers of our deeper emotions, Kahneman as the explorer of our more humdrum cognitive processes. But that time has not yet come. Meanwhile, we must be grateful to Kahneman for giving us in this book a joyful understanding of the practical side of our personalities. _Freeman DysonWe should be grateful to Dyson for pointing out this important fact: Human experience is far broader than that which can be studied and explained by psychological experimentation.
Just as good science must be supported and reinforced by good philosophy, so must good science be complemented by deep and time-tested insights into human nature that come from a wide range of fields outside of traditional science.