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Nassim Nicholas Talebs bok The Black Swan: The Impact of the Highly Improbable passer glimrende til å beskrive finanskrisen. Mennesket regner bare med det vante og sannsylige. Det kvantifiserer erfaringer, men kalkulerer ikke med det uventede og usannsylige. Det som kommer out of the blue. 9/11 er selvfølgelig den ultimate Sorte Svane, men begrepet omfatter noe langt mer.

Jeg husker Joachim Fest skrev at Hitler var den siste statsmann som kunne forme historien på en så vilkårlig måte. I dag er det systemene som rår. Ingen nasjonale ledere kan fri seg fra dem. Men vi vet at Irans ledere vil ha atombomben og snakker om å eliminere Israel fra kartet. De tror på mahdiens gjenkomst og vil gjerne hjelpe historien på vei, slik leninistene i sin tid trodde de kunne.

Talebs ideer er spennende. Han mener den moderne verden er et slikt aggregat av krefter at det oppstår større potensial for brå hendelser, for brudd og high impact. Når en hendelse har stor nok gjennomslagskraft, endrer den hele situasjonen, slik 9/11 gjorde det. En annen faktor i dagens verden er hurtighet. Tingene skjer så fort at politikere ikke rekker å handle.

Vår evne til å forutse er begrenset. At ny teknologi skulle resultere i skyttegravskrigen under 1. verdenskrig, hadde ingen drømt om. Men selv etter at den var en realitet, fortsatte politikere og militære å pøse på med soldater som om liv ikke betød noen ting. Denne råskapen var en vesentlig årsak til nazismens og leninismens suksesser.

Vi føler oss så mye klokere enn general Haig, og tror vi har lært. Men vi har ikke lært noen ting. Vi har bare lært at skyttergravskrigen var dumskap. Selv Aldri mer! er blitt til «aldri mer skal tyskerne få sende jødene i gasskammeret».

Taleb ble født i 1965 i Libanon, og flyktet til USA da borgerkrigen brøt ut i 1975. Det var en rystende opplevelse. Samfunnet slik man var vant til, preget av sameksistens og toleranse, gikk under og er aldri kommet seg.

Taleb ber oss tenke på våre personlige liv. De fleste oss har opplevd plustelige hendelser som har gjort at våre liv endrer kurs. Det kan være møter med mennesker eller ulykker og sykdom, en eksamen, en jobb, tilfeldighetene er mange. Han får oss til å tenke på oss selv som romanfigurer: Hvilke små endringer skal til før vår liv tar en annen retning, kanskje umerkelig til å begynne med, men vi ender opp et helt annet sted.

Spesielt fascinerende er hans tanker om de stille heltene. Mennesker som har gjort noe som avverget katastrofer, men fordi de lyktes er vi uvitende om deres bidrag! De vet kanskje ikke en gang selv hva deres bidrag betød, men dør anonymt.

But there are even more mistreated heroes-the very sad category of those who we do not know were heroes, who saved our lives, who helped us avoid disasters. They left no traces and did not even know that they were making a contribution. We remember the martyrs who died for a cause that we knew about, never those no less effective in their contribution but whose cause we were never aware-precisely because they were successful.

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.

Taleb snakker om betydningen av det negative – det vi ikke vet. Den virkelig kloke tar høyde for det ukjente eller uventede, det uforutsigelige, i sine planer. Det vil alltid være til stede som Det store ukjente.

Vår tid har opphevet denne ydmykheten, og vi oppfører oss som vi kjenner svarene.

Fra innledningen:

Before the discovery of Australia, people in the old world were convinced that all swans were white, an unassailable belief as it seemed completely confirmed by empirical evidence. The sighting of the first black swan might have been an interesting surprise for a few ornithologists (and others extremely concerned with the coloring of birds), but that is not where the significance of the story lies. It illustrates a severe limitation to our learning from observations or experience and the fragility of our knowledge. One single observation can invalidate a general statement derived from millennia of confirmatory sightings of millions of white swans. All you need is one single (and, I am told, quite ugly) black bird.

I push one step beyond this philosophical-logical question into an empirical reality, and one that has obsessed me since childhood. What we call here a Black Swan (and capitalize it) is an event with the following three attributes.

First, it is an outlier, as it lies outside the realm of regular expectations, because nothing in the past can convincingly point to its possibility. Second, it carries an extreme impact. Third, in spite of its outlier status, human nature makes us concoct explanations for its occurrence after the fact, making it explainable and predictable.

I stop and summarize the triplet: rarity, extreme impact, and retrospective (though not prospective) predictability. A small number of Black Swans explain almost everything in our world, from the success of ideas and religions, to the dynamics of historical events, to elements of our own personal lives. Ever since we left the Pleistocene, some ten millennia ago, the effect of these Black Swans has been increasing. It started accelerating during the industrial revolution, as the world started getting more complicated, while ordinary events, the ones we study and discuss and try to predict from reading the newspapers, have become increasingly inconsequential.

Just imagine how little your understanding of the world on the eve of the events of 1914 would have helped you guess what was to happen next. (Don’t cheat by using the explanations drilled into your cranium by your dull high school teacher). How about the rise of Hitler and the subsequent war? How about the precipitous demise of the Soviet bloc? How about the rise of Islamic fundamentalism? How about the spread of the Internet? How about the market crash of 1987 (and the more unexpected recovery)? Fads, epidemics, fashion, ideas, the emergence of art genres and schools. All follow these Black Swan dynamics. Literally, just about everything of significance around you might qualify.

This combination of low predictability and large impact makes the Black Swan a great puzzle; but that is not yet the core concern of this book. Add to this phenomenon the fact that we tend to act as if it does not exist! I don’t mean just you, your cousin Joey, and me, but almost all «social scientists» who, for over a century, have operated under the false belief that their tools could measure uncertainty. For the applications of the sciences of uncertainty to real-world problems has had ridiculous effects; I have been privileged to see it in finance and economics. Go ask your portfolio manager for his definition of «risk,» and odds are that he will supply you with a measure that excludes the possibility of the Black Swan-hence one that has no better predictive value for assessing the total risks than astrology (we will see how they dress up the intellectual fraud with mathematics). This problem is endemic in social matters.

The central idea of this book concerns our blindness with respect to randomness, particularly the large deviations: Why do we, scientists or nonscientists, hotshots or regular Joes, tend to see the pennies instead of the dollars? Why do we keep focusing on the minutiae, not the possible significant large events, in spite of the obvious evidence of their huge influence? And, if you follow my argument, why does reading the newspaper actually decrease your knowledge of the world?

It is easy to see that life is the cumulative effect of a handful of significant shocks. It is not so hard to identify the role of Black Swans, from your armchair (or bar stool). Go through the following exercise. Look into your own existence. Count the significant events, the technological changes, and the inventions that have taken place in our environment since you were born and compare them to what was expected before their advent. How many of them came on a schedule? Look into your own personal life, to your choice of profession, say, or meeting your mate, your exile from your country of origin, the betrayals you faced, your sudden enrichment or impoverishment. How often did these things occur according to plan?

What You Do Not Know

Black Swan logic makes what you don’t know far more relevant than what you do know. Consider that many Black Swans can be caused and exacerbated by their being unexpected.

‘The Black Swan: The Impact of the Highly Improbable,’ by Nassim Nicholas Taleb: Possibly Maybe (April 22, 2007)

Innledningen fortsetter på: ‘The Black Swan: The Impact of the Highly Improbable’