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Mental Models

Zorglubs Crowding the Attic

Taleb uses Monte Carlo simulations of evolving populations and traders to develop intuitions about survival across possible histories. In his trader models, some option buyers survive conditions that eliminate bullish and bearish strategies.

THE IDEA

Zorglubs Crowding the Attic

My Monte Carlo engine took me on a few interesting adventures. While my colleagues were immersed in news stories, central bank announcements, earnings reports, economic forecasts, sports results, and, not least, office politics, I started toying with it in fields bordering my home base of financial probability. A natural field of expansion for the amateur is evolutionary biology—the universality of its message and its application to markets are appealing. I started simulating populations of fast-mutating animals called Zorglubs under climatic changes and witnessing the most unexpected of conclusions—some of the results are recycled in Chapter 5. My aim, as a pure amateur fleeing the boredom of business life, was merely to develop intuitions for these events—the sort of intuitions that amateurs build away from the overly detailed sophistication of the professional researcher. I also toyed with molecular biology, generating randomly occurring cancer cells and witnessing some surprising aspects of their evolution. Naturally the analog to fabricating populations of Zorglubs was to simulate a population of “idiotic bull,” “impetuous bear,” and “cautious” traders under different market regimes, say booms and busts, and to examine their short-term and long-term survival. Under such a structure, “idiotic bull” traders who get rich from the rally would use the proceeds to buy more assets, driving prices higher, until their ultimate shellacking. Bearish traders, though, rarely made it in the boom to get to the bust. My models showed that ultimately almost nobody really survived; bears dropped out like flies in the rally and bulls ended up being slaughtered, as paper profits vanished when the music stopped. But there was one exception; some of those who traded options (I called them option buyers) had remarkable staying power and I wanted to be one of those. How? Because they could buy the insurance against blowup; they could get anxiety-free sleep at night, thanks to the knowledge that if their careers were threatened, it would not be owing to the outcome of a single day.

If the tone of this book seems steeped in the culture of Darwinism and evolutionary thinking, it does not come from any remotely formal training in the natural sciences, but from the evolutionary way of thinking taught by my Monte Carlo simulators.

I reckon that I outgrew the desire to generate random runs every time I want to explore an idea—but by dint of playing with a Monte Carlo engine for years I can no longer visualize a realized outcome without reference to the nonrealized ones. I call that “summing under histories,” borrowing the expression from the colorful physicist Richard Feynman who applied such methods to examine the dynamics of subatomic particles.

Using my Monte Carlo to make and remake history reminded me of the experimental novels (the so-called new novels) by such writers as Alain Robbe-Grillet, popular in the 1960s and 1970s. There the same chapter would be written and revised, the writer each time changing the plot like a new sample path. Somehow the author was freed from the past situation he helped create and allowed himself the indulgence to change the plot retroactively.

When to use it

  • A portfolio manager uses Monte Carlo simulation to assess the probability of losing more than 10% over a year.

  • An entrepreneur simulates different business strategies under varying economic scenarios to decide which is most resilient.

  • A biologist simulates population dynamics under climate change to predict extinction risks.

  • An options trader uses the concept of buying insurance (put options) to protect against market crashes.

FROM THEORY TO EVERYDAY LIFE

In practice

01

Zorglub Population Simulation

Taleb simulates fast-mutating animals he calls Zorglubs under changing climates to explore evolutionary outcomes. This excerpt describes the exercise but does not give its particular results.

02

Trader Behavior Simulation

Simulated three types of traders—idiotic bulls, impetuous bears, and cautious traders—under boom and bust market regimes. Bulls got rich in rallies but were slaughtered when the music stopped; bears rarely survived the boom to profit from the bust. Only option buyers, who used insurance, had lasting survival.

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A MOMENT TO REFLECT

Put it to work.

  1. How might you use Monte Carlo simulation to test the robustness of your investment strategy under different market conditions?

  2. In what areas of your life (business, personal) could you apply 'summing under histories' to consider alternative outcomes?

  3. What might be the equivalent of 'option buying' (insurance) in your career or decisions to protect against catastrophic losses?

Connected ideas

Another lens can bring the same problem into focus.

CONTINUE THE CONVERSATION

Source texts

  • Fooled by Randomness The Hidden Role of Chance in the Markets and in Life (Nassim Nicholas Taleb)
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