poker with your friends. Try to envision the shape of the resulting puddle.
Operation 2 (where did the water come from?): Consider a puddle of
water on the floor. Now try to reconstruct in your mind's eye the shape of
the ice cube it may once have been. Note that the puddle may not have
necessarily originated from an ice cube.
The second operation is harder. Helenus indeed had to have skills.
The difference between these two processes resides in the following. If
you have the right models (and some time on your hands, and nothing better
to do) you can predict with great precision how the ice cube will melt—
this is a specific engineering problem devoid of complexity, easier than the
one involving billiard balls. However, from the pool of water you can
build infinite possible ice cubes, if there was in fact an ice cube there at all.
The first direction, from the ice cube to the puddle, is called the forward
process. The second direction, the backward process, is much, much more
complicated. The forward process is generally used in physics and engineering;
the backward process in nonrepeatable, nonexperimental historical
approaches.
In a way, the limitations that prevent us from unfrying an egg also
prevent us from reverse engineering history.
Now, let me increase the complexity of the forward-backward problem
just a bit by assuming nonlinearity. Take what is generally called the
"butterfly in India" paradigm from the discussion of Lorenz's discovery in
the previous chapter. As we have seen, a small input in a complex system
can lead to nonrandom large results, depending on very special conditions.
A single butterfly flapping its wings in New Delhi may be the certain
cause of a hurricane in North Carolina, though the hurricane may take
EPISTEMOCRACY, A DREAM 1 97
place a couple of years later. However, given the observation of a hurricane
in North Carolina, it is dubious that you could figure out the causes
with any precision: there are billions of billions of such small things as
wing-flapping butterflies in Timbuktu or sneezing wild dogs in Australia
that could have caused it. The process from the butterfly to the hurricane
is greatly simpler than the reverse process from the hurricane to the potential
butterfly.
Confusion between the two is disastrously widespread in common culture.
This "butterfly in India" metaphor has fooled at least one filmmaker.
For instance, Happenstance (a.k.a. The Beating of a Butterfly's Wings), a
French-language film by one Laurent Firode, meant to encourage people
to focus on small things that can change the course of their lives. Hey,
since a small event (a petal falling on the ground and getting your attention)
can lead to your choosing one person over another as a mate for life,
you should focus on these very small details. Neither the filmmaker nor
the critics realized that they were dealing with the backward process; there
are trillions of such small things in the course of a simple day, and examining
all of them lies outside of our reach.
Once Again, Incomplete Information
Take a personal computer. You can use a spreadsheet program to generate
a random sequence, a succession of points we can call a history. How? The
computer program responds to a very complicated equation of a nonlinear
nature that produces numbers that seem random. The equation is very
simple: if you know it, you can predict the sequence. It is almost impossible,
however, for a human being to reverse engineer the equation and predict
further sequences. I am talking about a simple one-line computer
program (called the "tent map") generating a handful of data points, not
about the billions of simultaneous events that constitute the real history of
the world. In other words, even if history were a nonrandom series generated
by some "equation of the world," as long as reverse engineering such
an equation does not seem within human possibility, it should be deemed
random and not bear the name "deterministic chaos." Historians should
stay away from chaos theory and the difficulties of reverse engineering except
to discuss general properties of the world and learn the limits of what
they can't know.
This brings me to a greater problem with the historian's craft. I will
1 9 8 WE J U S T C A N ' T P R E D I CT
state the fundamental problem of practice as follows: while in theory randomness
is an intrinsic property, in practice, randomness is incomplete information,
what I called opacity in Chapter 1.
Nonpractitioners of randomness do not understand the subtlety.
Often, in conferences when they hear me talk about uncertainty and randomness,
philosophers, and sometimes mathematicians, bug me about the
least relevant point, namely whether the randomness I address is "true
randomness" or "deterministic chaos" that masquerades as randomness.
A true random system is in fact random and does not have predictable
properties. A chaotic system has entirely predictable properties, but they
are hard to know. So my answer to them is dual.
a) There is no functional difference in practice between the two since
we will never get to make the distinction—the difference is mathematical,
not practical. If I see a pregnant woman, the sex of her child is a purely
random matter to me (a 50 percent chance for either sex)—but not to her
doctor, who might have done an ultrasound. In practice, randomness is
fundamentally incomplete information.
b) The mere fact that a person is talking about the difference implies
that he has never made a meaningful decision under uncertainty—which is
why he does not realize that they are indistinguishable in practice.
Randomness, in the end, is just unknowledge. The world is opaque
and appearances fool us.
What They Call Knowledge
One final word on history.
History is like a museum where one can go to see the repository of the
past, and taste the charm of olden days. It is a wonderful mirror in which
we can see our own narratives. You can even track the past using DNA
analyses. I am fond of literary history. Ancient history satisfies my desire
to build my own self-narrative, my identity, to connect with my (complicated)
Eastern Mediterranean roots. I even prefer the accounts of older,
patently less accurate books to modern ones. Among the authors I've
reread (the ultimate test of whether you like an author is if you've reread
him) the following come to mind: Plutarch, Livy, Suetonius, Diodorus
Siculus, Gibbon, Carlyle, Renan, and Michelet. These accounts are patently
substandard, compared to today's works; they are largely anecdotal, and
full of myths. But I know this.
History is useful for the thrill of knowing the past, and for the narraEPISTEMOCRACY,
A DREAM 1 99
tive (indeed), provided it remains a harmless narrative. One should learn
under severe caution. History is certainly not a place to theorize or derive
general knowledge, nor is it meant to help in the future, without some caution.
We can get negative confirmation from history, which is invaluable,
but we get plenty of illusions of knowledge along with it.
This brings me back once again to Menodotus and the treatment of the
turkey problem and how to not be a sucker for the past. The empirical
doctor's approach to the problem of induction was to know history without
theorizing from it. Learn to read history, get all the knowledge you
can, do not frown on the anecdote, but do not draw any causal links, do
not try to reverse engineer too much—but if you do, do not make big scientific
claims. Remember that the empirical skeptics had respect for custom:
they used it as a default, a basis for action, but not for more than
that. This clean approach to the past they called epilogism.*
But most historians have another opinion. Consider the representative
introspection What Is History? by Edward Hallett Carr. You will catch
him explicitly pursuing causation as a central aspect of his job. You can
even go higher up: Herodotus, deemed to be the father of the subject, defined
his purpose in the opening of his work:
To preserve a memory of the deeds of the Greeks and barbarians, "and
in particular, beyond everything else, to give a cause [emphasis mine]
to their fighting one another."
You see the same with all theoreticians of history, whether Ibn Khaldoun,
Marx, or Hegel. The more we try to turn history into anything other
than an enumeration of accounts to be enjoyed with minimal theorizing, the
more we get into trouble. Are we so plagued with the narrative fallacy?!
* Yogi Berra might have a theory of epilogism with his saying, "You can observe a
lot by just watching."
f While looking at the past it would be a good idea to resist na?ve analogies. Many
people have compared the United States today to Ancient Rome, both from a military
standpoint (the destruction of Carthage was often invoked as an incentive for
the destruction of enemy regimes) and from a social one (the endless platitudinous
warnings of the upcoming decline and fall). Alas, we need to be extremely careful
in transposing knowledge from a simple environment that is closer to type 1, like
the one we had in antiquity, to today's type 2, complex system, with its intricate
webs of casual links. Another error is to draw casual conclusions from the absence
of nuclear war, since, invoking the Casanova argument of Chapter 8,1 would repeat
that we would not be here had a nuclear war taken place, and it is not a good
idea for us to derive a "cause" when our survival is conditioned on that cause.
2 0 0 WE J U S T C A N ' T PREDICT
We may have to wait for a generation of skeptical-empiricist historians
capable of understanding the difference between a forward process and a
reverse one.
Just as Popper attacked the historicists in their making claims about
the future, I have just presented the weakness of the historical approach in
knowing the past itself.
After this discussion about future (and past) blindness, let us see what to
do about it. Remarkably, there are extremely practical measures we can
take. We will explore this next.
Chapter Thirteen
APPELLES THE PAINTER, OR WHAT DO
YOU DO IF YOU CANNOT PREDICT?*
You should charge people for advice—My two cents here—Nobody knows
anything, but, at least, he knows it—Go to parties
ADVICE IS CHEAP, VERY CHEAP
It is not a good habit to stuff one's text with quotations from prominent
thinkers, except to make fun of them or provide a historical reference.
They "make sense," but well-sounding maxims force themselves on our
gullibility and do not always stand up to empirical tests. So I chose the ioU
lowing statement by the ùberphilosopher Bertrand Russell precisely because
I disagree with it.
The demand for certainty is one which is natural to man, but is nevertheless
an intellectual vice. If you take your children for a picnic on a
doubtful day, they will demand a dogmatic answer as to whether it
will be fine or wet, and be disappointed in you when you cannot be
sure. . . .
* This chapter provides a general conclusion for those who by now say, "Taleb, I get
the point, but what should I do?" My answer is that if you got the point, you are
pretty much there. But here is a nudge.
2 0 2 WE J U S T C A N ' T PREDICT
The reader may be surprised that I disagree. It is hard to disagree that
the demand for certainty is an intellectual vice. It is hard to disagree
that we can be led astray by some cocksure prophet. Where I beg to differ
with the great man is that I do not believe in the track record of advicegiving
"philosophy" in helping us deal with the problem; nor do I believe
that virtues can be easily taught; nor do I urge people to strain in order to
avoid making a judgment. Why? Because we have to deal with humans as
humans. We cannot teach people to withhold judgment; judgments are
embedded in the way we view objects. I do not see a "tree"; I see a pleasant
or an ugly tree. It is not possible without great, paralyzing effort to
strip these small values we attach to matters. Likewise, it is not possible to
hold a situation in one's head without some element of bias. Something in
our dear human nature makes us want to believe; so what?
Philosophers since Aristotle have taught us that we are deep-thinking
animals, and that we can learn by reasoning. It took a while to discover
that we do effectively think, but that we more readily narrate backward in
order to give ourselves the illusion of understanding, and give a cover to
our past actions. The minute we forgot about this point, the "Enlightenment"
came to drill it into our heads for a second time.
I'd rather degrade us humans to a level certainly above other known
animals but not quite on a par with the ideal Olympian man who can absorb
philosophical statements and act accordingly. Indeed, if philosophy
were that effective, the self-help section of the local bookstore would be of
some use in consoling souls experiencing pain—but it isn't. We forget to
philosophize when under strain.
I'll end this section on prediction with the following two lessons, one
very brief (for the small matters), one rather lengthy (for the large, important
decisions).
But so long as men are not trained [emphasis mine] to withhold
judgment in the absence of evidence, they will be led astray by cocksure
prophets . . . For the learning of every virtue there is an appropriate
discipline, and for the learning of suspended judgment the best
discipline is philosophy.
A P P E L L E S T H E P A I N T E R , O R W H A T D O Y O U D O I F Y O U C A N N O T P R E D I C T ? 2 03
Being a Fool in the Right Places
The lesson for the small is: be human! Accept that being human involves
some amount of epistemic arrogance in running your affairs. Do not be
ashamed of that. Do not try to always withhold judgment—opinions are
the stuff of life. Do not try to avoid predicting—yes, after this diatribe
about prediction I am not urging you to stop being a fool. Just be a fool in
