et cetera. (You can easily get them from the kitchens of
fancy New York restaurants.) With these thousands of rats, you build a
heterogeneous cohort, one that is well representative of the general New
York rat population. You bring them to my laboratory on East Fifty-ninth
Street in New York City and we put the entire collection in a large vat. We
subject the rats to increasingly higher levels of radiation (since this is supposed
to be a thought experiment, I am told that there is no cruelty in the
process). At every level of radiation, those that are naturally stronger (and
this is the key) will survive; the dead will drop out of your sample. We will
progressively have a stronger and stronger collection of rats. Note the following
central fact: every single rat, including the strong ones, will be
weaker after the radiation than before.
An observer endowed with analytical abilities, who probably got excellent
grades in college, would be led to believe that treatment in my laboratory
is an excellent health-club replacement, and one that could be
generalized to all mammals (think of the potential commercial success).
His logic would run as follows: Hey, these rats are stronger than the rest
of the rat population. What do they seem to have in common? They all
came from that Black Swan guy Taleb's workshop. Not many people will
have the temptation to go look at the dead rats.
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Next we pull the following trick on The New York Times: we let these
surviving rats loose in New York City and inform the chief rodent correspondent
of the newsworthy disruption in the pecking order in the New
York rat population. He will write a lengthy (and analytical) article on the
social dynamics of New York rats that includes the following passage:
"Those rats are now bullies in the rat population. They literally run the
show. Strengthened by their experience in the laboratory of the reclusive
(but friendly) statistician/philosopher/trader Dr. Taleb, they . . . "
Vicious Bias
There is a vicious attribute to the bias: it can hide best when its impact is
largest. Owing to the invisibility of the dead rats, the more lethal the risks,
the less visible they will be, since the severely victimized are likely to be
eliminated from the evidence. The more injurious the treatment, the larger
the difference between the surviving rats and the rest, and the more fooled
you will be about the strengthening effect. One of the two following ingredients
is necessary for this difference between the true effect (weakening)
and the observed one (strengthening): a) a degree of inequality in strength,
or diversity, in the base cohort, or b) unevenness, or diversity, somewhere
in the treatment. Diversity here has to do with the degree of uncertainty
inherent in the process.
More Hidden Applications
We can keep going with this argument; it has such universality that once
we get the bug it is hard to look at reality with the same eyes again. Clearly
it robs our observations of their realistic power. I will enumerate a few
more cases to illustrate the weaknesses of our inferential machinery.
The stability of species. Take the number of species that we now consider
extinct. For a long time scientists took the number of such species as
that implied from an analysis of the extant fossils. But this number ignores
the silent cemetery of species that came and left without leaving traces in
the form of fossils; the fossils that we have managed to find correspond to
a smaller proportion of all species that came and disappeared. This implies
that our biodiversity was far greater than it seemed at first examination. A
more worrisome consequence is that the rate of extinction of species may
be far greater than we think—close to 99.5 percent of species that transited
through earth are now extinct, a number of scientists have kept raisGIACOMO
CASANOVA'S UNFAILING LUCK 1 09
ing through time. Life is a great deal more fragile than we have allowed
for. But this does not mean we (humans) should feel guilty for extinctions
around us; nor does it mean that we should act to stop them—species were
coming and going before we started messing up the environment. There is
no need to feel moral responsibility for every endangered species.
Does crime pay? Newspapers report on the criminals who get caught.
There is no section in The New York Times recording the stories of those
who committed crimes but have not been caught. So it is with cases of
tax evasion, government bribes, prostitution rings, poisoning of wealthy
spouses (with substances that do not have a name and cannot be detected),
and drug trafficking.
In addition, our representation of the standard criminal might be
based on the properties of those less intelligent ones who were caught.
Once we seep ourselves into the notion of silent evidence, so many
things around us that were previously hidden start manifesting themselves.
Having spent a couple of decades in this mind-set, I am convinced
(but cannot prove) that training and education can help us avoid its pitfalls.
The Evolution of the Swimmer's Body
What do the popular expressions "a swimmer's body" and "beginner's
luck" have in common? What do they seem to share with the concept of
history?
There is a belief among gamblers that beginners are almost always
lucky. "It gets worse later, but gamblers are always lucky when they start
out," you hear. This statement is actually empirically true: researchers
confirm that gamblers have lucky beginnings (the same applies to stock
market speculators). Does this mean that each one of us should become a
gambler for a while, take advantage of lady luck's friendliness to beginners,
then stop?
The answer is no. The same optical illusion prevails: those who start
gambling will be either lucky or unlucky (given that the casino has the advantage,
a slightly greater number will be unlucky). The lucky ones, with
the feeling of having been selected by destiny, will continue gambling; the
others, discouraged, will stop and will not show up in the sample. They
will probably take up, depending on their temperaments, bird-watching,
Scrabble, piracy, or other pastimes. Those who continue gambling will remember
having been lucky as beginners. The dropouts, by definition, will
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no longer be part of the surviving gamblers' community. This explains beginner's
luck.
There is an analogy with what is called in common parlance a "swimmer's
body," which led to a mistake I shamefully made a few years ago (in
spite of my specialty in this bias, I did not notice that I was being fooled).
When asking around about the comparative physical elegance of athletes,
I was often told that runners looked anorexic, cyclists bottom-heavy, and
weight lifters insecure and a little primitive. I inferred that I should spend
some time inhaling chlorine, in the New York University pool to get those
"elongated muscles." Now suspend the causality. Assume that a person's
genetic variance allows for a certain type of body shape. Those born with
a natural tendency to develop a swimmer's body become better swimmers.
These are the ones you see in your sample splashing up and down at the
pools. But they would have looked pretty much the same if they lifted
weights. It is a fact that a given muscle grows exactly the same way
whether you take steroids or climb walls at the local gym.
WHAT YOU SEE AND WHAT YOU DON'T SEE
Katrina, the devastating hurricane that hit New Orleans in 2005, got
plenty of politicizing politicians on television. These legislators, moved by
the images of devastation and the pictures of angry victims made homeless,
made promises of "rebuilding." It was so noble on their part to do
something humanitarian, to rise above our abject selfishness.
Did they promise to do so with their own money? No. It was with public
money. Consider that such funds will be taken away from somewhere
else, as in the saying "You take from Peter to give to Paul." That somewhere
else will be less mediatized. It may be privately funded cancer research,
or the next efforts to curb diabetes. Few seem to pay attention to
the victims of cancer lying lonely in a state of untelevised depression. Not
only do these cancer patients not vote (they will be dead by the next ballot),
but they do not manifest themselves to our emotional system. More
of them die every day than were killed by Hurricane Katrina; they are the
ones who need us the most—not just our financial help, but our attention
and kindness. And they may be the ones from whom the money will be
taken—indirectly, perhaps even directly. Money (public or private) taken
away from research might be responsible for killing them—in a crime that
may remain silent.
A ramification of the idea concerns our decision making under a cloud
GIACOMO CASANOVA'S UNFAILING LUCK 1 1 1
of possibilities. We see the obvious and visible consequences, not the invisible
and less obvious ones. Yet those unseen consequences can be—nay,
generally are—more meaningful.
Frédéric Bastiat was a nineteenth-century humanist of a strange variety,
one of those rare independent thinkers—independent to the point of
being unknown in his own country, France, since his ideas ran counter to
French political orthodoxy (he joins another of my favorite thinkers,
Pierre Bayle, in being unknown at home and in his own language). But he
has a large number of followers in America.
In his essay "What We See and What We Don't See," Bastiat offered
the following idea: we can see what governments do, and therefore sing
their praises—but we do not see the alternative. But there is an alternative;
it is less obvious and remains unseen.
Recall the confirmation fallacy: governments are great at telling you
what they did, but not what they did not do. In fact, they engage in what
could be labeled as phony "philanthropy," the activity of helping people
in a visible and sensational way without taking into account the unseen
cemetery of invisible consequences. Bastiat inspired libertarians by attacking
the usual arguments that showed the benefits of governments. But his
ideas can be generalized to apply to both the Right and the Left.
Bastiat goes a bit deeper. If both the positive and the negative consequences
of an action fell on its author, our learning would be fast. But
often an action's positive consequences benefit only its author, since they
are visible, while the negative consequences, being invisible, apply to others,
with a net cost to society. Consider job-protection measures: you notice
those whose jobs are made safe and ascribe social benefits to such
protections. You do not notice the effect on those who cannot find a job
as a result, since the measure will reduce job openings. In some cases, as
with the cancer patients who may be punished by Katrina, the positive
consequences of an action will immediately benefit the politicians and
phony humanitarians, while the negative ones take a long time to appear—
they may never become noticeable. One can even blame the press for directing
charitable contributions toward those who may need them the
least.
Let us apply this reasoning to September 11, 2001. Around twenty-five
hundred people were directly killed by bin Laden's group in the Twin
Towers of the World Trade Center. Their families benefited from the support
of all manner of agencies and charities, as they should. But, according
to researchers, during the remaining three months of the year, close to
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one thousand people died as silent victims of the terrorists. How? Those
who were afraid of flying and switched to driving ran an increased risk of
death. There was evidence of an increase of casualties on the road during
that period; the road is considerably more lethal than the skies. These
families got no support—they did not even know that their loved ones
were also the victims of bin Laden.
In addition to Bastiat, I have a weakness for Ralph Nader (the activist
and consumer advocate, certainly not the politician and political thinker).
He may be the American citizen who saved the highest number of lives by
exposing the safety record of car companies. But, in his political campaign
a few years ago, even he forgot to trumpet the tens of thousands of lives
saved by his seat belt laws. It is much easier to sell "Look what I did for
you" than "Look what I avoided for you."
Recall from the Prologue the story of the hypothetical legislator whose
actions might have avoided the attack of September 11. How many such
people are walking the street without the upright gait of the phony hero?
Have the guts to consider the silent consequences when standing in
front of the next snake-oil humanitarian.
Doctors
Our neglect of silent evidence kills people daily. Assume that a drug saves
many people from a potentially dangerous ailment, but runs the risk of
killing a few, with a net benefit to society. Would a doctor prescribe it? He
has no incentive to do so. The lawyers of the person hurt by the side effects
will go after the doctor like attack dogs, while the lives saved by the
drug might not be accounted for anywhere.
A life saved is a statistic; a person hurt is an anecdote. Statistics are invisible;
anecdotes are salient. Likewise, the risk of a Black Swan is invisible.
THE TEFLON-STYLE PROTECTION OF GIACOMO CASANOVA
This brings us to gravest of all manifestations of silent evidence, the illusion
of stability. The bias lowers our perception of the risks we incurred in
the past, particularly for those of us who were lucky to have survived
them. Your life came under a serious threat but, having survived it, you
retrospectively underestimate how risky the situation actually was.
The adventurer Giacomo Casanova, later self-styled Jacques, Chevalier
de Seingalt, the wannabe intellectual and legendary seducer of women,
