With the born storyteller''s command of narrative and
imaginative approach, Leonard Mlodinow vividly demonstrates how our
lives are profoundly informed by chance and randomness and how
everything from wine ratings and corporate success to school grades
and political polls are less reliable than we believe.
By showing us the true nature of chance and revealing the
psychological illusions that cause us to misjudge the world around
us, Mlodinow gives us the tools we need to make more informed
內容簡介:
With the born storyteller''s command of narrative and imaginative
approach, Leonard Mlodinow vividly demonstrates how our lives are
profoundly informed by chance and randomness and how everything
from wine ratings and corporate success to school grades and
political polls are less reliable than we believe.
By showing us the
true nature of chance and revealing the psychological illusions
that cause us to misjudge the world around us, Mlodinow gives us
the tools we need to make more informed decisions. From the
classroom to the courtroom and from financial markets to
supermarkets, Mlodinow''s intriguing and illuminating look at how
randomness, chance, and probability affect our daily lives will
intrigue, awe, and inspire.
關於作者:
Leonard Mlodinow received his doctorate in physics from the
University of California, Berkeley, was an Alexander von Humboldt
fellow at the Max Planck Institute, and now teaches about
randomness to future scientists at Caltech. Along the way he also
wrote for the television series MacGyver and Star Trek:
The Next Generation. His previous books include Euclid''s
Window: The Story of Geometry from Parallel Lines to Hyperspace,
Feynman''s Rainbow: A Search for Beauty in Physics and in Life,
and, with Stephen Hawking, A Briefer History of Time. He
lives in South Pasadena, California.
From the Hardcover edition.
目錄:
Prologue
Chapter 1: Peering through the Eyepiece
of Randomness
The hidden role of chance . . . when human beings can be
outperformed by a rat.
Chapter 2: The Laws of Truths and
Half-Truths
The basic principles of probability and how they are abused . .
. why a good story is often less likely to be true than a flimsy
explanation.
Chapter 3: Finding Your Way through a Space
of Possibilities
A framework for thinking about random situations . . . from a
gambler in plague-ridden Italy to Let’s Make a
Deal.
Chapter 4: Tracking the Pathways to Success
How to count the number of ways in which events can happen, and
why it matters . . . the mathematical meaning of
expectation.
Chapter 5: The Dueling Laws of Large and
Small Numbers
The extent to which probabilities are reflected in the results
we observe . . . Zeno’s paradox, the concept of limits, and beating
the casino at roulette.
Chapter 6: False Positives and
Positive Fallacies
How to adjust expectations in light of past events or new
knowledge . . . mistakes in conditional probability from medical
screening to the O. J. Simpson trial and the prosecutor’s
fallacy.
Chapter 7: Measurement and the Law of
Errors
The meaning and lack of meaning in measurements . . . the bell
curve and wine ratings, political polls, grades, and the position
of planets.
Chapter 8: The Order in Chaos
How large numbers can wash out the disorder of randomness . . .
or why 200,000,000 drivers form a creature of habit.
Chapter 9: Illusions of Patterns and Patterns of Illusion
Why we are often fooled by the regularities in chance events . .
. can a million consecutive zeroes or the success of Wall Street
gurus be random?
Chapter 10: The Drunkard’s Walk
Why chance is a more fundamental conception than causality . . .
Bruce Willis, Bill Gates, and the normal accident theory of
life.
Acknowledgments
Notes
Index
內容試閱:
Peering through the Eyepiece of Randomness
I remember, as a teenager, watching the yellow flame of the
Sabbath candles dancing randomly above the white paraffin cylinders
that fueled them. I was too young to think candlelight romantic,
but still I found it magical-because of the flickering images
created by the fire. They shifted and morphed, grew and waned, all
without apparent cause or plan. Surely, I believed, there must be
rhyme and reason underlying the flame, some pattern that scientists
could predict and explain with their mathematical equations. "Life
isn''t like that," my father told me. "Sometimes things happen that
cannot be foreseen." He told me of the time when, in Buchenwald,
the Nazi concentration camp in which he was imprisoned and
starving, he stole a loaf of bread from the bakery. The baker had
the Gestapo gather everyone who might have committed the crime and
line the suspects up. "Who stole the bread?" the baker asked. When
no one answered, he told the guards to shoot the suspects one by
one until either they were all dead or someone confessed. My father
stepped forward to spare the others. He did not try to paint
himself in a heroic light but told me that he did it because he
expected to be shot either way. Instead of having him killed,
though, the baker gave my father a plum job, as his assistant. "A
chance event," my father said. "It had nothing to do with you, but
had it happened differently, you would never have been born." It
struck me then that I have Hitler to thank for my existence, for
the Germans had killed my father''s wife and two young children,
erasing his prior life. And so were it not for the war, my father
would never have emigrated to New York, never have met my mother,
also a refugee, and never have produced me and my two
brothers.
My father rarely spoke of the war. I didn''t realize it then, but
years later it dawned on me that whenever he shared his ordeals, it
was not so much because he wanted me to know of his experiences but
rather because he wanted to impart a larger lesson about life. War
is an extreme circumstance, but the role of chance in our lives is
not predicated on extremes. The outline of our lives, like the
candle''s flame, is continuously coaxed in new directions by a
variety of random events that, along with our responses to them,
determine our fate. As a result, life is both hard to predict and
hard to interpret. Just as, looking at a Rorschach blot, you might
see Madonna and I, a duck-billed platypus, the data we encounter in
business, law, medicine, sports, the media, or your child''s
third-grade report card can be read in many ways. Yet interpreting
the role of chance in an event is not like intepreting a Rorschach
blot; there are right ways and wrong ways to do
it.
We often employ intuitive processes when we make assessments and
choices in uncertain situations. Those processes no doubt carried
an evolutionary advantage when we had to decide whether a
saber-toothed tiger was smiling because it was fat and happy or
because it was famished and saw us as its next meal. But the modern
world has a different balance, and today those intuitive processes
come with drawbacks. When we use our habitual ways of thinking to
deal with today''s tigers, we can be led to decisions that are less
than optimal or even incongruous. That conclusion comes as no
surprise to those who study how the brain processes uncertainty:
many studies point to a close connection between the parts of our
brain that make assessments of chance situations and those that
handle the human characteristic that is often considered our prime
source of irrationality-our emotions. Functional magnetic resonance
imaging, for example, shows that risk and reward are assessed by
parts of the dopaminergic system, a brain-reward circuit important
for motivational and emotional processes. The images show, too,
that the amygdala, which is also linked to our emotional state,
especially fear, is activated when we make decisions couched in
uncertainty.
The mechanisms by which people analyze situations involving
chance are an intricate product of evolutionary factors, brain
structure, personal experience, knowledge, and emotion. In fact,
the human response to uncertainty is so complex that sometimes
different structures within the brain come to different conclusions
and apparently fight it out to determine which one will dominate.
For example, if your face swells to five times its normal size
three out of every four times you eat shrimp, the "logical" left
hemisphere of your brain will attempt to find a pattern. The
"intuitive" right hemisphere of your brain, on the other hand, will
simply say "avoid shrimp." At least that''s what researchers found
in less painful experimental setups. The game is called probability
guessing. In lieu of toying with shrimp and histamine, subjects are
shown a series of cards or lights, which can have two colors, say
green and red. Things are arranged so that the colors will appear
with different probabilities but otherwise without a pattern. For
example, red might appear twice as often as green in a sequence
like red-red-green-red-green-red-red-green-green-red-red-red, and
so on. The task of the subject, after watching for a while, is to
predict whether each new member of the sequence will be red or
green.
The game has two basic strategies. One is to always guess the
color that you notice occurs more frequently. That is the route
favored by rats and other nonhuman animals. If you employ this
strategy, you are guaranteed a certain degree of success but you
are also conceding that you will do no better. For instance, if
green shows up 75 percent of the time and you decide to always
guess green, you will be correct 75 percent of the time. The other
strategy is to "match" your proportion of green and red guesses to
the proportion of green and red you observed in the past. If the
greens and reds appear in a pattern and you can figure out the
pattern, this strategy enables you to guess right every time. But
if the colors appear at random, you would be better off sticking
with the first strategy. In the case where green randomly appears
75 percent of the time, the second strategy will lead to the
correct guess only about 6 times in 10.
Humans usually try to guess the pattern, and in the process we
allow ourselves to be outperformed by a rat. But there are people
with certain types of post-surgical brain impairment-called a split
brain-that precludes the right and left hemispheres of the brain
from communicating with each other. If the probability experiment
is performed on these patients such that they see the colored light
or card with only their left eye and employ only their left hand to
signal their predictions, it amounts to an experiment on the right
side of the brain. But if the experiment is performed so as to
involve only their right eye and right hand, it is an experiment on
the left brain. When researchers performed those experiments, they
found that-in the same patients-the right hemisphere always chose
to guess the more frequent color and the left hemisphere always
tried to guess the pattern.
Making wise assessments and choices in the face of uncertainty is
a rare skill. But like any skill, it can be improved with
experience. In the pages that follow, I will examine the role of
chance in the world around us, the ideas that have been developed
over the centuries to help us understand that role, and the factors
that often lead us astray. The British philosopher and
mathematician Bertrand Russell wrote,
We all start from "naive realism," i.e., the doctrine that things
are what they seem. We think that grass is green, that stones are
hard, and that snow is cold. But physics assures us that the
greenness of grass, the hardness of stones, and the coldness of
snow are not the greenness of grass, the hardness of stones, and
the coldness of snow that we know in our own experience, but
something very different. In what follows we will peer at life
through the eyepiece of randomness and see that many of the events
of our lives, too, are not quite what they seem but rather
something very different.
In 2002 the Nobel committee awarded the Nobel Prize in Economics
to a scientist named Daniel Kahneman. Economists do all sorts of
things these days-they explain why teachers are paid so little, why
football teams are worth so much, and why bodily functions help set
a limit on the size of hog farms a hog excretes three to five
times as much as a human, so a farm with thousands of hogs on it
often produces more waste than the neighboring cities. Despite all
the great research generated by economists, the 2002 Nobel Prize
was notable because Kahneman is not an economist. He is a
psychologist, and for decades, with the late Amos Tversky, Kahneman
studied and clarified the kinds of misperceptions of randomness
that fuel many of the common fallacies I will talk about in this
book.
The greatest challenge in understanding the role of randomness in
life is that although the basic principles of randomness arise from
everyday logic, many of the consequences that follow from those
principles prove counterintuitive. Kahneman and Tversky''s studies
were themselves spurred by a random event. In the mid-1960s,
Kahneman, then a junior psychology professor at Hebrew University,
agreed to perform a rather unexciting chore: lecturing to a group
of Israeli air force flight instructors on the conventional wisdom
of behavior modification and its application to the psychology of
flight training. Kahneman drove home the point that rewarding
positive behavior works but punishing mistakes does not. One of his
students interrupted, voicing an opinion that would lead Kahneman
to an epiphany and guide his research for
decades.
"I''ve often praised people warmly for beautifully executed
maneuvers, and the next time they always do worse," the flight
instructor said. "And I''ve...