employment on September 10, 2001; it imposes the continuously locked
bulletproof doors in every cockpit (at high costs to the struggling airlines)—
just in case terrorists decide to use planes to attack the World Trade
Center in New York City. I know this is lunacy, but it is just a thought
experiment (I am aware that there may be no such thing as a legislator
with intellect, courage, vision, and perseverance; this is the point of the
thought experiment). The legislation is not a popular measure among the
airline personnel, as it complicates their lives. But it would certainly have
prevented 9/11.
The person who imposed locks on cockpit doors gets no statues in
public squares, not so much as a quick mention of his contribution in his
obituary. "Joe Smith, who helped avoid the disaster of 9/11, died of complications
of liver disease." Seeing how superfluous his measure was, and
how it squandered resources, the public, with great help from airline pilots,
might well boot him out of office. Vox clamantis in deserto. He will
retire depressed, with a great sense of failure. He will die with the impression
of having done nothing useful. I wish I could go attend his funeral,
but, reader, I can't find him. And yet, recognition can be quite a pump. Believe
me, even those who genuinely claim that they do not believe in recognition,
and that they separate labor from the fruits of labor, actually get a
serotonin kick from it. See how the silent hero is rewarded: even his own
hormonal system will conspire to offer no reward.
Now consider again the events of 9/11. In their aftermath, who got the
recognition? Those you saw in the media, on television performing heroic
acts, and those whom you saw trying to give you the impression that they
were performing heroic acts. The latter category includes someone like
the New York Stock Exchange chairman Richard Grasso, who "saved the
stock exchange" and received a huge bonus for his contribution (the
equivalent of several thousand average salaries). All he had to do was be
there to ring the opening bell on television—the television that, we will
see, is the carrier of unfairness and a major cause of Black Swan blindness.
Who gets rewarded, the central banker who avoids a recession or the
xxiv PROLOGUE
one who comes to "correct" his predecessors' faults and happens to be
there during some economic recovery? Who is more valuable, the politician
who avoids a war or the one who starts a new one (and is lucky
enough to win)?
It is the same logic reversal we saw earlier with the value of what we
don't know; everybody knows that you need more prevention than treatment,
but few reward acts of prevention. We glorify those who left their
names in history books at the expense of those contributors about whom
our books are silent. We humans are not just a superficial race (this may
be curable to some extent); we are a very unfair one.
LIFE IS VERY UNUSUAL
This is a book about uncertainty; to this author, the rare event equals
uncertainty. This may seem like a strong statement—that we need to principally
study the rare and extreme events in order to figure out common
ones—but I will make myself clear as follows. There are two possible
ways to approach phenomena. The first is to rule out the extraordinary
and focus on the "normal." The examiner leaves aside "outliers" and
studies ordinary cases. The second approach is to consider that in order
to understand a phenomenon, one needs first to consider the extremes—
particularly if, like the Black Swan, they carry an extraordinary cumulative
effect.
I don't particularly care about the usual. If you want to get an idea of
a friend's temperament, ethics, and personal elegance, you need to look at
him under the tests of severe circumstances, not under the regular rosy
glow of daily life. Can you assess the danger a criminal poses by examining
only what he does on an ordinary day? Can we understand health
without considering wild diseases and epidemics? Indeed the normal is
often irrelevant.
Almost everything in social life is produced by rare but consequential
shocks and jumps; all the while almost everything studied about social life
focuses on the "normal," particularly with "bell curve" methods of inference
that tell you close to nothing. Why? Because the bell curve ignores
large deviations, cannot handle them, yet makes us confident that we have
tamed uncertainty. Its nickname in this book is GIF, Great Intellectual
Fraud.
P R O L O G U E xxv
PLATO AND THE NERD
At the start of the Jewish revolt in the first century of our era, much of the
Jews' anger was caused by the Romans' insistence on putting a statue
of Caligula in their temple in Jerusalem in exchange for placing a statue of
the Jewish god Yahweh in Roman temples. The Romans did not realize
that what the Jews (and the subsequent Levantine monotheists) meant by
god was abstract, all embracing, and had nothing to do with the anthropomorphic,
too human representation that Romans had in mind when
they said deus. Critically, the Jewish god did not lend himself to symbolic
representation. Likewise, what many people commoditize and label as
"unknown," "improbable,"or "uncertain" is not the same thing to me; it
is not a concrete and precise category of knowledge, a nerdified field, but
its opposite; it is the lack (and limitations) of knowledge. It is the exact
contrary of knowledge; one should learn to avoid using terms made for
knowledge to describe its opposite.
What I call Platonicity, after the ideas (and personality) of the philosopher
Plato, is our tendency to mistake the map for the territory, to focus on
pure and well-defined "forms," whether objects, like triangles, or social
notions, like Utopias (societies built according to some blueprint of what
"makes sense"), even nationalities. When these ideas and crisp constructs
inhabit our minds, we privilege them over other less elegant objects, those
with messier and less tractable structures (an idea that I will elaborate progressively
throughout this book).
Platonicity is what makes us think that we understand more than we
actually do. But this does not happen everywhere. I am not saying that
Platonic forms don't exist. Models and constructions, these intellectual
maps of reality, are not always wrong; they are wrong only in some specific
applications. The difficulty is that a) you do not know beforehand
(only after the fact) where the map will be wrong, and b) the mistakes can
lead to severe consequences. These models are like potentially helpful
medicines that carry random but very severe side effects.
The Platonic fold is the explosive boundary where the Platonic mindset
enters in contact with messy reality, where the gap between what you
know and what you think you know becomes dangerously wide. It is here
that the Black Swan is produced.
xxvi PROLOGUE
TOO DULL TO WRITE ABOUT
It was said that the artistic filmmaker Luchino Visconti made sure that
when actors pointed at a closed box meant to contain jewels, there were
real jewels inside. It could be an effective way to make actors live their
part. I think that Visconti's gesture may also come out of a plain sense of
aesthetics and a desire for authenticity—somehow it may not feel right to
fool the viewer.
This is an essay expressing a primary idea; it is neither the recycling
nor repackaging of other people's thoughts. An essay is an impulsive meditation,
not science reporting. I apologize if I skip a few obvious topics in
this book out of the conviction that what is too dull for me to write about
might be too dull for the reader to read. (Also, to avoid dullness may help
to filter out the nonessential.)
Talk is cheap. Someone who took too many philosophy classes in college
(or perhaps not enough) might object that the sighting of a Black
Swan does not invalidate the theory that all swans are white since such a
black bird is not technically a swan since whiteness to him may be the essential
property of a swan. Indeed those who read too much Wittgenstein
(and writings about comments about Wittgenstein) may be under the impression
that language problems are important. They may certainly be important
to attain prominence in philosophy departments, but they are
something we, practitioners and decision makers in the real world, leave
for the weekend. As I explain in the chapter called "The Uncertainty of the
Phony," for all of their intellectual appeal, these niceties have no serious
implications Monday to Friday as opposed to more substantial (but neglected)
matters. People in the classroom, not having faced many true situations
of decision making under uncertainty, do not realize what is
important and what is not—even those who are scholars of uncertainty
(or particularly those who are scholars of uncertainty). What I call the
practice of uncertainty can be piracy, commodity speculation, professional
gambling, working in some branches of the Mafia, or just plain serial entrepreneur
ship. Thus I rail against "sterile skepticism," the kind we can do
nothing about, and against the exceedingly theoretical language problems
that have made much of modern philosophy largely irrelevant to what is
derisively called the "general public." (In the past, for better or worse,
those rare philosophers and thinkers who were not self-standing depended
on a patron's support. Today academics in abstract disciplines depend on
one another's opinion, without external checks, with the severe occasional
P R O L O G U E xxvii
pathological result of turning their pursuits into insular prowess-showing
contests. Whatever the shortcomings of the old system, at least it enforced
some standard of relevance.)
The philosopher Edna Ullmann-Margalit detected an inconsistency in
this book and asked me to justify the use of the precise metaphor of a Black
Swan to describe the unknown, the abstract, and imprecise uncertain—
white ravens, pink elephants, or evaporating denizens of a remote planet
orbiting Tau Ceti. Indeed, she caught me red handed. There is a contradiction;
this book is a story, and I prefer to use stories and vignettes to illustrate
our gullibility about stories and our preference for the dangerous
compression of narratives.
You need a story to displace a story. Metaphors and stories are far
more potent (alas) than ideas; they are also easier to remember and more
fun to read. If I have to go after what I call the narrative disciplines, my
best tool is a narrative.
Ideas come and go, stories stay.
THE BOTTOM LINE
The beast in this book is not just the bell curve and the self-deceiving statistician,
nor the Platonified scholar who needs theories to fool himself
with. It is the drive to "focus" on what makes sense to us. Living on our
planet, today, requires a lot more imagination than we are made to have.
We lack imagination and repress it in others.
Note that I am not relying in this book on the beastly method of collecting
selective "corroborating evidence." For reasons I explain in Chapter
5, I call this overload of examples na?ve empiricism—successions of
anecdotes selected to fit a story do not constitute evidence. Anyone looking
for confirmation will find enough of it to deceive himself—and no
doubt his peers.* The Black Swan idea is based on the structure of randomness
in empirical reality.
To summarize: in this (personal) essay, I stick my neck out and make a
claim, against many of our habits of thought, that our world is dominated
by the extreme, the unknown, and the very improbable (improbable ac-
* It is also na?ve empiricism to provide, in support of some argument, series of eloquent
confirmatory quotes by dead authorities. By searching, you can always find
someone who made a well-sounding statement that confirms your point of view—
and, on every topic, it is possible to find another dead thinker who said the exact
opposite. Almost all of my non-Yogi Berra quotes are from people I disagree with.
xxviii PROLOGUE
cording our current knowledge)—and all the while we spend our time engaged
in small talk, focusing on the known, and the repeated. This implies
the need to use the extreme event as a starting point and not treat it as an
exception to be pushed under the rug. I also make the bolder (and more
annoying) claim that in spite of our progress and the growth in knowledge,
or perhaps because of such progress and growth, the future will be
increasingly less predictable, while both human nature and social "science"
seem to conspire to hide the idea from us.
Chapters Map
The sequence of this book follows a simple logic; it flows from what can
be labeled purely literary (in subject and treatment) to what can be
deemed entirely scientific (in subject, though not in treatment). Psychology
will be mostly present in Part One and in the early part of Part Two; business
and natural science will be dealt with mostly in the second half of Part
Two and in Part Three. Part One, "Umberto Eco's Antilibrary," is mostly
about how we perceive historical and current events and what distortions
are present in such perception. Part Two, "We Just Can't Predict," is
about our errors in dealing with the future and the unadvertised limitations
of some "sciences"—and what to do about these limitations. Part
Three, "Those Gray Swans of Extremistan," goes deeper into the topic of
extreme events, explains how the bell curve (that great intellectual fraud)
is generated, and reviews the ideas in tlie natural and social sciences
loosely lumped under the label "complexity." Part Four, "The End," will
be very short.
I derived an unexpected amount of enjoyment writing this book—in fact,
it just wrote itself—and I hope that the reader will experience the same. I
confess that I got hooked on this withdrawal into pure ideas after the constraints
of an active and transactional life. After this book is published, my
