Some excerpts from the book:
“In the markets, fixing prices, or, equivalently, eliminating speculators, the so-called “noise traders”—and the moderate volatility that they bring—provide an illusion of stability, with periods of calm punctuated with large jumps. Because players are unused to volatility, the slightest price variation will then be attributed to insider information, or to changes in the state of the system, and will cause panics. When a currency never varies, a slight, very slight move makes people believe that the world is ending. Injecting some confusion stabilizes the system.”
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“In social policy, it consists in protecting the very weak and letting the strong do their job, rather than helping the middle class to consolidate its privileges, thus blocking evolution and bringing all manner of economic problems that tend to hurt the poor the most.”
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“two types of knowledge. The first type is not exactly “knowledge”; its ambiguous character prevents us from associating it with the strict definitions of knowledge. It is a way of doing things that we cannot really express in clear and direct language—it is sometimes called apophatic—but that we do nevertheless, and do well. The second type is more like what we call “knowledge”; it is what you acquire in school, can get grades for, can codify, what is explainable, academizable, rationalizable, formalizable, theoretizable, codifiable, Sovietizable, bureaucratizable, Harvardifiable, provable, etc. The error of naive rationalism leads to overestimating the role and necessity of the second type, academic knowledge, in human affairs—and degrading the uncodifiable, more complex, intuitive, or experience-based type.”
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“The important difference between theory and practice lies precisely in the detection of the sequence of events and retaining the sequence in memory. If life is lived forward but remembered backward, as Kierkegaard observed, then books exacerbate this effect—our own memories, learning, and instinct have sequences in them. Someone standing today looking at events without having lived them would be inclined to develop illusions of causality, mostly from being mixed-up by the sequence of events. In real life, in spite of all the biases, we do not have the same number of asynchronies that appear to the student of history. Nasty history, full of lies, full of biases!”
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“the fooled by randomness effect: mistaking the merely associative for the causal, that is, if rich countries are educated, immediately inferring that education makes a country rich, without even checking. Epiphenomenon here again. (The error in reasoning is a bit from wishful thinking, because education is considered “good”; I wonder why people don’t make the epiphenomenal association between the wealth of a country and something “bad,” say, decadence, and infer that decadence, or some other disease of wealth like a high suicide rate, also generates wealth.) I am not saying that for an individual, education is useless: it builds helpful credentials for one’s own career—but such effect washes out at the country level. Education stabilizes the income of families across generations. A merchant makes money, then his children go to the Sorbonne, they become doctors and magistrates. The family retains wealth because the diplomas allow members to remain in the middle class long after the ancestral wealth is depleted. But these effects don’t count for countries.”
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"there are two domains, the ludic, which is set up like a game, with its rules supplied in advance in an explicit way, and the ecological, where we don’t know the rules and cannot isolate variables, as in real life. Seeing the nontransferability of skills from one domain to the other led me to skepticism in general about whatever skills are acquired in a classroom, anything in a non-ecological way, as compared to street fights and real-life situations."
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"There is this error of thinking that things always have a reason that is accessible to us—that we can comprehend easily. Indeed, the most severe mistake made in life is to mistake the unintelligible for the unintelligent-"
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"exposure is more important than knowledge; decision effects supersede logic. Textbook “knowledge” misses a dimension, the hidden asymmetry of benefits—just like the notion of average. The need to focus on the payoff from your actions instead of studying the structure of the world (or understanding the “True” and the “False”) has been largely missed in intellectual history. Horribly missed. The payoff, what happens to you (the benefits or harm from it), is always the most important thing, not the event itself."
"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)."
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"the problem is deeply ingrained in standard reactions; the 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."
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"In addition to the medical empirics, this section has attempted to vindicate the unreasonable mavericks, engineers, freelance entrepreneurs, innovative artists, and anti-academic thinkers who have been reviled by history. Some of them had great courage—not just the courage to put forth their ideas, but the courage to accept to live in a world they knew they did not understand. And they enjoyed it."
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"this method can show us where the math in economic models is bogus—which models are fragile and which ones are not. Simply do a small change in the assumptions, and look at how large the effect, and if there is acceleration of such effect."
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"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."
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"What survives must be good at serving some (mostly hidden) purpose that time can see but our eyes and logical faculties can’t capture."
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"the way to do it rigorously, according to the notions of fragility and antifragility, is to take away from the future, reduce from it, simply, things that do not belong to the coming times. Via negativa."
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"I insist on the via negativa method of prophecy as being the only valid one: there is no other way to produce a forecast without being a turkey somewhere, particularly in the complex environment in which we live today. Now, I am not saying that new technologies will not emerge—something new will rule its day, for a while. What is currently fragile will be replaced by something else, of course. But this “something else” is unpredictable. In all likelihood, the technologies you have in your mind are not the ones that will make it, no matter your perception of their fitness and applicability—with all due respect to your imagination."
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"When asked to imagine the future, we have the tendency to take the present as a baseline, then produce a speculative destiny by adding new technologies and products to it and what sort of makes sense, given an interpolation of past developments. We also represent society according to our utopia of the moment, largely driven by our wishes—except for a few people called doomsayers, the future will be largely inhabited by our desires. So we will tend to over-technologize it and underestimate the might of the equivalent of these small wheels on suitcases that will be staring at us for the next millennia."
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"And the past—properly handled, as we will see in the next section—is a much better teacher about the properties of the future than the present. To understand the future, you do not need technoautistic jargon, obsession with “killer apps,” these sort of things. You just need the following: some respect for the past, some curiosity about the historical record, a hunger for the wisdom of the elders, and a grasp of the notion of “heuristics,” these often unwritten rules of thumb that are so determining of survival. In other words, you will be forced to give weight to things that have been around, things that have survived."
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"The perishable is typically an object, the nonperishable has an informational nature to it. A single car is perishable, but the automobile as a technology has survived about a century (and we will speculate should survive another one). Humans die, but their genes—a code—do not necessarily. The physical book is perishable—say, a specific copy of the Old Testament—but its contents are not, as they can be expressed into another physical book."
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"If you announce to someone “you lost $ 10,000,” he will be much more upset than if you tell him “your portfolio value, which was $ 785,000, is now $ 775,000.” Our brains have a predilection for shortcuts, and the variation is easier to notice (and store) than the entire record. It requires less memory storage. This psychological heuristic (often operating without our awareness), the error of variation in place of total, is quite pervasive, even with matters that are visual.
We notice what varies and changes more than what plays a large role but doesn’t change."
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"top-down is usually irreversible, so mistakes tend to stick, whereas bottom-up is gradual and incremental, with creation and destruction along the way, though presumably with a positive slope."
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"People in risk management only consider risky things that have hurt them in the past (given their focus on “evidence”), not realizing that, in the past, before these events took place, these occurrences that hurt them severely were completely without precedent, escaping standards."
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"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."
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"The hidden costs of health care are largely in the denial of antifragility. But it may not be just medicine—what we call diseases of civilization result from the attempt by humans to make life comfortable for ourselves against our own interest, since the comfortable is what fragilizes."
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"Evolution proceeds by undirected, convex bricolage or tinkering, inherently robust, i.e., with the achievement of potential stochastic gains thanks to continuous, repetitive, small, localized mistakes. What men have done with top-down, command-and-control science has been exactly the reverse: interventions with negative convexity effects, i.e., the achievement of small certain gains through exposure to massive potential mistakes."
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"iatrogenics is the result of wealth and sophistication rather than poverty and artlessness, and of course the product of partial knowledge rather than ignorance."
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"If true wealth consists in worriless sleeping, clear conscience, reciprocal gratitude, absence of envy, good appetite, muscle strength, physical energy, frequent laughs, no meals alone, no gym class, some physical labor (or hobby), good bowel movements, no meeting rooms, and periodic surprises, then it is largely subtractive (elimination of iatrogenics)."
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“Never ask anyone for their opinion, forecast, or recommendation. Just ask them what they have—or don’t have—in their portfolio.”
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"one side of a decision has larger consequences than the other—we don’t have evidence that people are terrorists but we check them for weapons; we don’t believe the water is poisonous but we avoid drinking it; something that would be absurd for someone narrowly applying Aristotelian logic."
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"My suggestion to deter “too big to fail” and prevent employers from taking advantage of the public is as follows. A company that is classified as potentially bailable out should it fail should not be able to pay anyone more than a corresponding civil servant. Otherwise people should be free to pay each other what they want since it does not affect the taxpayer. Such limitation would force companies to stay small enough that they would not be considered for a bailout in the event of their failure."
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"Those who have wrong heuristics—but with a small harm in the event of error—will survive. Behavior called “irrational” can be good if it is harmless."
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"Barbell Strategy: A dual strategy, a combination of two extremes, one safe and one speculative, deemed more robust than a “monomodal” strategy; often a necessary condition for antifragility. For instance, in biological systems, the equivalent of marrying an accountant and having an occasional fling with a rock star; for a writer, getting a stable sinecure and writing without the pressures of the market during spare time. Even trial and error are a form of barbell."
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"They showed in a remarkable study that the purpose of arguments is not to make decisions but to convince others—since decisions we arrive at by reasoning are fraught with massive distortions. They showed it experimentally, producing evidence that individuals are better at forging arguments in a social setting (when there are others to convince) than when they are alone."
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"Anti-Enlightenment: For a review, Sternhell (2010), McMahon (2001), Delon (1997). Horkheimer and Adorno provide a powerful critique of the cosmeticism and sucker-traps in the ideas of modernity. And of course the works of John Gray, particularly Gray (1998) and Straw Dogs, Gray (2002)."
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