Even if we could rid ourselves of the biases and

Even if we could rid ourselves of the biases and illusions identified in
this book — and Kahneman, citing his own lack of progress in overcoming
them, doubts that we can — it is by no means clear that this would make our
lives go better. And that raises a fundamental question: What is the point of
rationality? We are, after all, Darwinian survivors. Our everyday reasoning
abilities have evolved to cope efficiently with a complex and dynamic
environment. They are thus likely to be adaptive in this environment, even if
they can be tripped up in the psychologist’s somewhat artificial experiments.
Where do the norms of rationality come from, if they are not an idealization

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Kahneman never grapples philosophically with the nature of rationality.
He does, however, supply a fascinating account of what might be taken to be
its goal: happiness. What does it mean to be happy? When Kahneman first
took up this question, in the mid 1990s, most happiness research relied on
asking people how satisfied they were with their life on the whole. But such
retrospective assessments depend on memory, which is notoriously
unreliable. What if, instead, a person’s actual experience of pleasure or pain
could be sampled from moment to moment, and then summed up over time?
Kahneman calls this “experienced” well-being, as opposed to the
“remembered” well-being that researchers had relied upon. And he found
that these two measures of happiness diverge in surprising ways. What
makes the “experiencing self” happy is not the same as what makes the
“remembering self” happy. In particular, the remembering self does not care
about duration — how long a pleasant or unpleasant experience lasts.
Rather, it retrospectively rates an experience by the peak level of pain or
pleasure in the course of the experience, and by the way the experience
ends.
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These two quirks of remembered happiness — “duration neglect” and
the “peak-end rule” — were strikingly illustrated in one of Kahneman’s more
harrowing experiments. Two groups of patients were to undergo painful
colonoscopies. The patients in Group A got the normal procedure. So did the
patients in Group B, except — without their being told — a few extra minutes
of mild discomfort were added after the end of the examination. Which group
suffered more? Well, Group B endured all the pain that Group A did, and then
some. But since the prolonging of Group B’s colonoscopies meant that the
procedure ended less painfully, the patients in this group retrospectively
minded it less. (In an earlier research paper though not in this book,
Kahneman suggested that the extra discomfort Group B was subjected to in
the experiment might be ethically justified if it increased their willingness to
come back for a follow-up!)

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