[Paleopsych] Louis Menand: Everybody's an Expert

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Louis Menand: Everybody's an Expert
http://www.newyorker.com/printables/critics/051205crbo_books1
Putting predictions to the test.
Issue of 2005-10-05
Posted 2005-11-28

Prediction is one of the pleasures of life. Conversation would wither without 
it. "It won't last. She'll dump him in a month." If you're wrong, no one will 
call you on it, because being right or wrong isn't really the point. The point 
is that you think he's not worthy of her, and the prediction is just a way of 
enhancing your judgment with a pleasant prevision of doom. Unless you're 
putting money on it, nothing is at stake except your reputation for wisdom in 
matters of the heart. If a month goes by and they're still together, the 
deadline can be extended without penalty. "She'll leave him, trust me. It's 
only a matter of time." They get married: "Funny things happen. You never 
know." You still weren't wrong. Either the marriage is a bad one?you erred in 
the right direction?or you got beaten by a low-probability outcome.

It is the somewhat gratifying lesson of Philip Tetlock's new book, "Expert 
Political Judgment: How Good Is It? How Can We Know?" (Princeton; $35), that 
people who make prediction their business?people who appear as experts on 
television, get quoted in newspaper articles, advise governments and 
businesses, and participate in punditry roundtables?are no better than the rest 
of us. When they're wrong, they're rarely held accountable, and they rarely 
admit it, either. They insist that they were just off on timing, or blindsided 
by an improbable event, or almost right, or wrong for the right reasons. They 
have the same repertoire of self-justifications that everyone has, and are no 
more inclined than anyone else to revise their beliefs about the way the world 
works, or ought to work, just because they made a mistake. No one is paying you 
for your gratuitous opinions about other people, but the experts are being 
paid, and Tetlock claims that the better known and more frequently quoted they 
are, the less reliable their guesses about the future are likely to be. The 
accuracy of an expert's predictions actually has an inverse relationship to his 
or her self-confidence, renown, and, beyond a certain point, depth of 
knowledge. People who follow current events by reading the papers and 
newsmagazines regularly can guess what is likely to happen about as accurately 
as the specialists whom the papers quote. Our system of expertise is completely 
inside out: it rewards bad judgments over good ones.

"Expert Political Judgment" is not a work of media criticism. Tetlock is a 
psychologist?he teaches at Berkeley?and his conclusions are based on a 
long-term study that he began twenty years ago. He picked two hundred and 
eighty-four people who made their living "commenting or offering advice on 
political and economic trends," and he started asking them to assess the 
probability that various things would or would not come to pass, both in the 
areas of the world in which they specialized and in areas about which they were 
not expert. Would there be a nonviolent end to apartheid in South Africa? Would 
Gorbachev be ousted in a coup? Would the United States go to war in the Persian 
Gulf? Would Canada disintegrate? (Many experts believed that it would, on the 
ground that Quebec would succeed in seceding.) And so on. By the end of the 
study, in 2003, the experts had made 82,361 forecasts. Tetlock also asked 
questions designed to determine how they reached their judgments, how they 
reacted when their predictions proved to be wrong, how they evaluated new 
information that did not support their views, and how they assessed the 
probability that rival theories and predictions were accurate.

Tetlock got a statistical handle on his task by putting most of the
forecasting questions into a "three possible futures" form. The
respondents were asked to rate the probability of three alternative
outcomes: the persistence of the status quo, more of something
(political freedom, economic growth), or less of something
(repression, recession). And he measured his experts on two
dimensions: how good they were at guessing probabilities (did all the
things they said had an x per cent chance of happening happen x per
cent of the time?), and how accurate they were at predicting specific
outcomes. The results were unimpressive. On the first scale, the
experts performed worse than they would have if they had simply
assigned an equal probability to all three outcomes?if they had given
each possible future a thirty-three-per-cent chance of occurring.
Human beings who spend their lives studying the state of the world, in
other words, are poorer forecasters than dart-throwing monkeys, who
would have distributed their picks evenly over the three choices.

Tetlock also found that specialists are not significantly more
reliable than non-specialists in guessing what is going to happen in
the region they study. Knowing a little might make someone a more
reliable forecaster, but Tetlock found that knowing a lot can actually
make a person less reliable. "We reach the point of diminishing
marginal predictive returns for knowledge disconcertingly quickly," he
reports. "In this age of academic hyperspecialization, there is no
reason for supposing that contributors to top journals?distinguished
political scientists, area study specialists, economists, and so
on?are any better than journalists or attentive readers of the New
York Times in 'reading' emerging situations." And the more famous the
forecaster the more overblown the forecasts. "Experts in demand,"
Tetlock says, "were more overconfident than their colleagues who eked
out existences far from the limelight."

People who are not experts in the psychology of expertise are likely
(I predict) to find Tetlock's results a surprise and a matter for
concern. For psychologists, though, nothing could be less surprising.
"Expert Political Judgment" is just one of more than a hundred studies
that have pitted experts against statistical or actuarial formulas,
and in almost all of those studies the people either do no better than
the formulas or do worse. In one study, college counsellors were given
information about a group of high-school students and asked to predict
their freshman grades in college. The counsellors had access to test
scores, grades, the results of personality and vocational tests, and
personal statements from the students, whom they were also permitted
to interview. Predictions that were produced by a formula using just
test scores and grades were more accurate. There are also many studies
showing that expertise and experience do not make someone a better
reader of the evidence. In one, data from a test used to diagnose
brain damage were given to a group of clinical psychologists and their
secretaries. The psychologists' diagnoses were no better than the
secretaries'.

The experts' trouble in Tetlock's study is exactly the trouble that
all human beings have: we fall in love with our hunches, and we
really, really hate to be wrong. Tetlock describes an experiment that
he witnessed thirty years ago in a Yale classroom. A rat was put in a
T-shaped maze. Food was placed in either the right or the left
transept of the T in a random sequence such that, over the long run,
the food was on the left sixty per cent of the time and on the right
forty per cent. Neither the students nor (needless to say) the rat was
told these frequencies. The students were asked to predict on which
side of the T the food would appear each time. The rat eventually
figured out that the food was on the left side more often than the
right, and it therefore nearly always went to the left, scoring
roughly sixty per cent?D, but a passing grade. The students looked for
patterns of left-right placement, and ended up scoring only fifty-two
per cent, an F. The rat, having no reputation to begin with, was not
embarrassed about being wrong two out of every five tries. But Yale
students, who do have reputations, searched for a hidden order in the
sequence. They couldn't deal with forty-per-cent error, so they ended
up with almost fifty-per-cent error.

The expert-prediction game is not much different. When television
pundits make predictions, the more ingenious their forecasts the
greater their cachet. An arresting new prediction means that the
expert has discovered a set of interlocking causes that no one else
has spotted, and that could lead to an outcome that the conventional
wisdom is ignoring. On shows like "The McLaughlin Group," these
experts never lose their reputations, or their jobs, because long
shots are their business. More serious commentators differ from the
pundits only in the degree of showmanship. These serious experts?the
think tankers and area-studies professors?are not entirely out to
entertain, but they are a little out to entertain, and both their
status as experts and their appeal as performers require them to
predict futures that are not obvious to the viewer. The producer of
the show does not want you and me to sit there listening to an expert
and thinking, I could have said that. The expert also suffers from
knowing too much: the more facts an expert has, the more information
is available to be enlisted in support of his or her pet theories, and
the more chains of causation he or she can find beguiling. This helps
explain why specialists fail to outguess non-specialists. The odds
tend to be with the obvious.

Tetlock's experts were also no different from the rest of us when it
came to learning from their mistakes. Most people tend to dismiss new
information that doesn't fit with what they already believe. Tetlock
found that his experts used a double standard: they were much tougher
in assessing the validity of information that undercut their theory
than they were in crediting information that supported it. The same
deficiency leads liberals to read only The Nation and conservatives to
read only National Review. We are not natural falsificationists: we
would rather find more reasons for believing what we already believe
than look for reasons that we might be wrong. In the terms of Karl
Popper's famous example, to verify our intuition that all swans are
white we look for lots more white swans, when what we should really be
looking for is one black swan.

Also, people tend to see the future as indeterminate and the past as
inevitable. If you look backward, the dots that lead up to Hitler or
the fall of the Soviet Union or the attacks on September 11th all
connect. If you look forward, it's just a random scatter of dots, many
potential chains of causation leading to many possible outcomes. We
have no idea today how tomorrow's invasion of a foreign land is going
to go; after the invasion, we can actually persuade ourselves that we
knew all along. The result seems inevitable, and therefore
predictable. Tetlock found that, consistent with this asymmetry,
experts routinely misremembered the degree of probability they had
assigned to an event after it came to pass. They claimed to have
predicted what happened with a higher degree of certainty than,
according to the record, they really did. When this was pointed out to
them, by Tetlock's researchers, they sometimes became defensive.

And, like most of us, experts violate a fundamental rule of
probabilities by tending to find scenarios with more variables more
likely. If a prediction needs two independent things to happen in
order for it to be true, its probability is the product of the
probability of each of the things it depends on. If there is a
one-in-three chance of x and a one-in-four chance of y, the
probability of both x and y occurring is one in twelve. But we often
feel instinctively that if the two events "fit together" in some
scenario the chance of both is greater, not less. The classic "Linda
problem" is an analogous case. In this experiment, subjects are told,
"Linda is thirty-one years old, single, outspoken, and very bright.
She majored in philosophy. As a student, she was deeply concerned with
issues of discrimination and social justice and also participated in
antinuclear demonstrations." They are then asked to rank the
probability of several possible descriptions of Linda today. Two of
them are "bank teller" and "bank teller and active in the feminist
movement." People rank the second description higher than the first,
even though, logically, its likelihood is smaller, because it requires
two things to be true?that Linda is a bank teller and that Linda is an
active feminist?rather than one.

Plausible detail makes us believers. When subjects were given a choice
between an insurance policy that covered hospitalization for any
reason and a policy that covered hospitalization for all accidents and
diseases, they were willing to pay a higher premium for the second
policy, because the added detail gave them a more vivid picture of the
circumstances in which it might be needed. In 1982, an experiment was
done with professional forecasters and planners. One group was asked
to assess the probability of "a complete suspension of diplomatic
relations between the U.S. and the Soviet Union, sometime in 1983,"
and another group was asked to assess the probability of "a Russian
invasion of Poland, and a complete suspension of diplomatic relations
between the U.S. and the Soviet Union, sometime in 1983." The experts
judged the second scenario more likely than the first, even though it
required two separate events to occur. They were seduced by the
detail.

It was no news to Tetlock, therefore, that experts got beaten by
formulas. But he does believe that he discovered something about why
some people make better forecasters than other people. It has to do
not with what the experts believe but with the way they think. Tetlock
uses Isaiah Berlin's metaphor from Archilochus, from his essay on
Tolstoy, "The Hedgehog and the Fox," to illustrate the difference. He
says:

Low scorers look like hedgehogs: thinkers who "know one big thing,"
aggressively extend the explanatory reach of that one big thing into
new domains, display bristly impatience with those who "do not get
it," and express considerable confidence that they are already pretty
proficient forecasters, at least in the long term. High scorers look
like foxes: thinkers who know many small things (tricks of their
trade), are skeptical of grand schemes, see explanation and prediction
not as deductive exercises but rather as exercises in flexible "ad
hocery" that require stitching together diverse sources of
information, and are rather diffident about their own forecasting
prowess.

A hedgehog is a person who sees international affairs to be ultimately
determined by a single bottom-line force: balance-of-power
considerations, or the clash of civilizations, or globalization and
the spread of free markets. A hedgehog is the kind of person who holds
a great-man theory of history, according to which the Cold War does
not end if there is no Ronald Reagan. Or he or she might adhere to the
"actor-dispensability thesis," according to which Soviet Communism was
doomed no matter what. Whatever it is, the big idea, and that idea
alone, dictates the probable outcome of events. For the hedgehog,
therefore, predictions that fail are only "off on timing," or are
"almost right," derailed by an unforeseeable accident. There are
always little swerves in the short run, but the long run irons them
out.

Foxes, on the other hand, don't see a single determining explanation
in history. They tend, Tetlock says, "to see the world as a shifting
mixture of self-fulfilling and self-negating prophecies:
self-fulfilling ones in which success breeds success, and failure,
failure but only up to a point, and then self-negating prophecies kick
in as people recognize that things have gone too far."

Tetlock did not find, in his sample, any significant correlation
between how experts think and what their politics are. His hedgehogs
were liberal as well as conservative, and the same with his foxes.
(Hedgehogs were, of course, more likely to be extreme politically,
whether rightist or leftist.) He also did not find that his foxes
scored higher because they were more cautious?that their appreciation
of complexity made them less likely to offer firm predictions. Unlike
hedgehogs, who actually performed worse in areas in which they
specialized, foxes enjoyed a modest benefit from expertise. Hedgehogs
routinely over-predicted: twenty per cent of the outcomes that
hedgehogs claimed were impossible or nearly impossible came to pass,
versus ten per cent for the foxes. More than thirty per cent of the
outcomes that hedgehogs thought were sure or near-sure did not,
against twenty per cent for foxes.

The upside of being a hedgehog, though, is that when you're right you
can be really and spectacularly right. Great scientists, for example,
are often hedgehogs. They value parsimony, the simpler solution over
the more complex. In world affairs, parsimony may be a liability?but,
even there, there can be traps in the kind of highly integrative
thinking that is characteristic of foxes. Elsewhere, Tetlock has
published an analysis of the political reasoning of Winston Churchill.
Churchill was not a man who let contradictory information interfere
with his id?es fixes. This led him to make the wrong prediction about
Indian independence, which he opposed. But it led him to be right
about Hitler. He was never distracted by the contingencies that might
combine to make the elimination of Hitler unnecessary.

Tetlock also has an unscientific point to make, which is that "we as a
society would be better off if participants in policy debates stated
their beliefs in testable forms"?that is, as probabilities?"monitored
their forecasting performance, and honored their reputational bets."
He thinks that we're suffering from our primitive attraction to
deterministic, overconfident hedgehogs. It's true that the only thing
the electronic media like better than a hedgehog is two hedgehogs who
don't agree. Tetlock notes, sadly, a point that Richard Posner has
made about these kinds of public intellectuals, which is that most of
them are dealing in "solidarity" goods, not "credence" goods. Their
analyses and predictions are tailored to make their ideological
brethren feel good?more white swans for the white-swan camp. A
prediction, in this context, is just an exclamation point added to an
analysis. Liberals want to hear that whatever conservatives are up to
is bound to go badly; when the argument gets more nuanced, they change
the channel. On radio and television and the editorial page, the line
between expertise and advocacy is very blurry, and pundits behave
exactly the way Tetlock says they will. Bush Administration loyalists
say that their predictions about postwar Iraq were correct, just a
little off on timing; pro-invasion liberals who are now trying to
dissociate themselves from an adventure gone bad insist that though
they may have sounded a false alarm, they erred "in the right
direction"?not really a mistake at all.

The same blurring characterizes professional forecasters as well. The
predictions on cable news commentary shows do not have life-and-death
side effects, but the predictions of people in the C.I.A. and the
Pentagon plainly do. It's possible that the psychologists have
something to teach those people, and, no doubt, psychologists are
consulted. Still, the suggestion that we can improve expert judgment
by applying the lessons of cognitive science and probability theory
belongs to the abiding modern American faith in expertise. As a
professional, Tetlock is, after all, an expert, and he would like to
believe in expertise. So he is distressed that political forecasters
turn out to be as unreliable as the psychological literature
predicted, but heartened to think that there might be a way of raising
the standard. The hope for a little more accountability is hard to
dissent from. It would be nice if there were fewer partisans on
television disguised as "analysts" and "experts" (and who would not
want to see more foxes?). But the best lesson of Tetlock's book may be
the one that he seems most reluctant to draw: Think for yourself.