Antifragile: Things That Gain From Disorder (Incerto, #4)

by Nassim Nicholas Taleb

The payoff, what happens to you (the benefits or harm from it), is always the most important thing, not the event itself.

Philosophers talk about truth and falsehood. People in life talk about payoff, exposure, and consequences (risks and rewards), hence fragility and antifragility. And sometimes philosophers and thinkers and those who study conflate Truth with risks and rewards.

My point taken further is that True and False (hence what we call “belief”) play a poor, secondary role in human decisions; it is the payoff from the True and the False that dominates—and it is almost always asymmetric, with one consequence much bigger than the other, i.e., harboring positive and negative asymmetries (fragile or antifragile).

You decide principally based on fragility, not probability. Or to rephrase, You decide principally based on fragility, not so much on True/False.

predictors’ reply when we point out their failures has typically been “we need better computation” in order to predict the event better and figure out the probabilities, instead of the vastly more effective “modify your exposure” and learn to get out of trouble, something religions and traditional heuristics have been better at enforcing than naive and cosmetic science.

For the fragile, the cumulative effect of small shocks is smaller than the single effect of an equivalent single large shock.

For the antifragile, shocks bring more benefits (equivalently, less harm) as their intensity increases (up to a point).

Black Swan effects are necessarily increasing, as a result of complexity, interdependence between parts, globalization, and the beastly thing called “efficiency” that makes people now sail too close to the wind.

One problem somewhere can halt the entire project—so the projects tend to get as weak as the weakest link in their chain (an acute negative convexity effect). The world is getting less and less predictable, and we rely more and more on technologies that have errors and interactions that are harder to estimate, let alone predict.

The number of cars is the something, a variable; traffic time is the function of something. The behavior of the function is such that it is, as we said, “not the same thing.” We can see here that the function of something becomes different from the something under nonlinearities.

The more nonlinear, the more the function of something divorces itself from the something. If traffic were linear, then there would be no difference in traffic time between the two following situations: 90,000, then 110,000 cars on the one hand, or 100,000 cars on the other.

The more volatile the something—the more uncertainty—the more the function divorces itself from the something. Let us consider the average number of cars again. The function (travel time) depends more on the volatility around the average. Things degrade if there is unevenness of distribution.

If the function is convex (antifragile), then the average of the function of something is going to be higher than the function of the average of something. And the reverse when the function is concave (fragile).

if you have favorable asymmetries, or positive convexity, options being a special case, then in the long run you will do reasonably well, outperforming the average in the presence of uncertainty. The more uncertainty, the more role for optionality to kick in, and the more you will outperform. This property is very central to life.

Yet in practice it is the negative that’s used by the pros, those selected by evolution: chess grandmasters usually win by not losing; people become rich by not going bust (particularly when others do); religions are mostly about interdicts; the learning of life is about what to avoid. You reduce most of your personal risks of accident thanks to a small number of measures.

Now when it comes to knowledge, the same applies. The greatest—and most robust—contribution to knowledge consists in removing what we think is wrong—subtractive epistemology.

So the central tenet of the epistemology I advocate is as follows: we know a lot more what is wrong than what is right, or, phrased according to the fragile/robust classification, negative knowledge (what is wrong, what does not work) is more robust to error than positive knowledge (what is right, what works).

If I spot a black swan (not capitalized), I can be quite certain that the statement “all swans are white” is wrong. But even if I have never seen a black swan, I can never hold such a statement to be true.

since one small observation can disprove a statement, while millions can hardly confirm it, disconfirmation is more rigorous than confirmation.

For the Arab scholar and religious leader Ali Bin Abi-Taleb (no relation), keeping one’s distance from an ignorant person is equivalent to keeping company with a wise man.

if you have more than one reason to do something (choose a doctor or veterinarian, hire a gardener or an employee, marry a person, go on a trip), just don’t do it. It does not mean that one reason is better than two, just that by invoking more than one reason you are trying to convince yourself to do something. Obvious decisions (robust to error) require no more than a single reason.

The problem in deciding whether a scientific result or a new “innovation” is a breakthrough, that is, the opposite of noise, is that one needs to see all aspects of the idea—and there is always some opacity that time, and only time, can dissipate.

One of my students (who was majoring in, of all subjects, economics) asked me for a rule on what to read. “As little as feasible from the last twenty years, except history books that are not about the last fifty years,” I

By issuing warnings based on vulnerability—that is, subtractive prophecy—we are closer to the original role of the prophet: to warn, not necessarily to predict, and to predict calamities if people don’t listen.

Let’s take this idea of Empedocles’ dog a bit further: If something that makes no sense to you (say, religion—if you are an atheist—or some age-old habit or practice called irrational); if that something has been around for a very, very long time, then, irrational or not, you can expect it to stick around much longer, and outlive those who call for its demise.

iatrogenics, being a cost-benefit situation, usually results from the treacherous condition in which the benefits are small, and visible—and the costs very large, delayed, and hidden. And of course, the potential costs are much worse than the cumulative gains.

And there is a simple statistical reason that explains why we have not been able to find drugs that make us feel unconditionally better when we are well (or unconditionally stronger, etc.): nature would have been likely to find this magic pill by itself.

consequence of Jensen’s inequality: irregularity has its benefits in some areas; regularity has its detriments.

If you take risks and face your fate with dignity, there is nothing you can do that makes you small; if you don’t take risks, there is nothing you can do that makes you grand, nothing. And when you take risks, insults by half-men (small men, those who don’t risk anything) are similar to barks by nonhuman animals: you can’t feel insulted by a dog.

The psychologist Gerd Gigerenzer has a simple heuristic. Never ask the doctor what you should do. Ask him what he would do if he were in your place.