Antifragile by Nassim Nicholas Taleb

Wind extinguishes a candle and energizes fire.

Antifragility is beyond resilience or robustness. The resilient resists shocks and stays the same; the antifragile gets better. 

Antifragility makes us understand fragility better. Just as we cannot improve health without reducing disease, or increase wealth without first decreasing losses, antifragility and fragility are degrees on a spectrum. 

It is far easier to figure out if something is fragile than to predict the occurrence of an event that may harm it. Fragility can be measured. This provides a solution to what I’ve called the Black Swan problem - the impossibility of calculating the risks of consequential rare events and predicting their occurrence. Sensitivity to harm from volatility is tractable, more so than forecasting the event that would cause the harm. So we propose to stand our current approaches to prediction, prognostication, and risk management on their heads.

We can almost always detect antifragility (and fragility) using a simple test of asymmetry; anything that has more upside than downside from random events (or certain shocks) is antifragile; the reverse is fragile.

If about everything top-down fragilizes and blocks antifragility and growth, everything bottom-up thrives under the right amount of stress and disorder. The process of discovery (or innovation, or technological progress) itself depends on antifragile tinkering, aggressive risk bearing rather than formal education. 

Black Swans are large-scale unpredictable and irregular events of massive consequence. Most of history comes from Black Swan events.

It is hard to see how things work by looking at single parts. 

The fragile breaks with time. 

George Santayana: A man is morally free when . . . he judges the world, and judges other men, with uncompromising sincerity. 

I want to be happy to be human and be in an environment in which other people are in love with their fate.

Hormesis, a word coined by pharmacologists, is when a small dose of a harmful substance is actually beneficial for the organism, acting as medicine. 

Humans somehow fail to recognize situations outside the contexts in which they usually learn about them.

The more energy you put into trying to control your ideas and what you think about, the more your ideas end up controlling you.

Many wreak their reputations merely by trying to defend it.

To estimate the quality of research, take the caliber of the highest detractor, or the caliber of the lowest detractor whom the author answers in print - whichever is lower.

Criticism itself can be antifragile to repression, when the fault finder wants to be attacked in return in order to get some validation.

It is not possible to stamp out criticism; if it harms you, get out. It is easier to change jobs than control your reputation or public perception.

You do not want to “control” your reputation: you won’t be able to do it by controlling information flow. Instead, focus on altering your exposure, say, by putting yourself in a position impervious to repetitional damage. Or even put yourself in a situation to benefit from the antifragility of information. 

With few exceptions, those who dress outrageously are robust or even antifragile in reputation; those clean-shaven types who dress in suits and ties are fragile to information about them.

When you don’t have debt you don’t care about your reputation in economic circles - and some how it is only when you don’t care about your reputation that you tend to have a good one. Just as in matters of seduction, people lend the most to those who need them the least. 

It is quite perplexing that those from whom we have benefited the most aren’t those who have tried to help us (say with “advice”) but rather those who have actively tried - but eventually failed - to harm us.

Artificial, man-made mechanical and engineering contraptions with simple responses are complicated, but not “complex,” as they don’t have interdependencies. You push a button, say, a light switch, and get an exact response, with no possible ambiguity in the consequences, even in Russia. But with complex systems, interdependencies are severe. You need to think in terms of ecology: if you remove a specific animal you disrupt a food chain: its predators will starve and its prey will grow unchecked, causing complications and series of cascading side effects. 

If nature ran the economy, it would not continuously bail out its living members to make them live forever.

Systems subjected to randomness - and unpredictability - build a mechanism beyond the robust to opportunistically reinvent themselves each generation, with a continuous change of population and species. 

While hormesis corresponds to situations by which the individual organism benefits from direct harm to itself, evolution occurs when harm makes the individual organism perish and the benefits are transferred to others, the surviving ones, and future generations. 

For instance, if you drink a poisonous substance in small amounts, the mechanism by which your organism gets better is, according to Danchin, evolutionary within your system, with bad (and weak) proteins in the cells replaced by stronger - and younger - ones and the stronger ones being spared (or some similar operation). When you starve yourself of food, it is the bad proteins that are broken down first and recycled by your own body - a process called autophagy. This is a purely evolutionary process, one that selects and kills the weakest for fitness. But one does not need to accept the specific biological theory (like aging proteins and autophagy) to buy the general idea that survival pressures within the organism play a role in its overall improvement under external stress.

When you are fragile, you depend on things following the exact planned course, with as little deviation as possible - for deviations are more harmful than helpful. This is why the fragile needs to be very predictive in its approach, and, conversely, predictive systems cause fragility. When you want deviations, and you don’t care about the possible dispersion of outcomes that the future can bring, since most will be helpful, you are antifragile. Further, the random element in trial and error is not quite random, if it is carried out rationally, using error as a source of information. If every trial provides you with information about what does not work, you start zooming in on a solution - so every attempt becomes more valuable, more like an expense than an error. And of course you make discoveries along the way.

It is often the mistakes of others that benefit the rest of us - and sadly, not them.

Those who perish contribute to the overall safety of others. There systems learn because they are antifragile and set up to exploit small errors.

Sometimes you only know about someone’s character after you harm them with an error for which you are solely responsible - I have been astonished at the generosity of some persons in the way they forgave me for my mistakes. 

You may never know what type of person someone is unless they are given opportunities to violate moral or ethical codes.

My characterization of a loser is someone who, after making a mistake, doesn’t introspect, doesn’t exploit it, feels embarrassed and defensive rather than enriched with a new piece of information, and tries to explain why he made the mistake rather than moving on.

He who has never sinned is less reliable than he who has only sinned once. And someone who has made plenty of errors - though never the same error more than once - is more reliable than someone who has never made any. 

Some class of rash, even suicidal, risk taking is healthy for the economy - under the condition that not all people take the same risks and that these ricks remain small and localized. 

We can mistake the antifragility of the system for that of the individual, when in fact it takes place at the expense of the individual (the difference between hormesis and selection). 

All we may be witnessing is that transfer of fragility (rather, antifragility) from the individual to the system that I discussed earlier. Let me present it in a different way. The surviving cohort, clearly, is stronger than the initial one - but not quite the individuals, since the weaker ones died. 

Entrepreneurship is a risky and heroic activity, necessary for growth or even the mere survival of the economy. 

I have noticed that the more people glorify the entrepreneur as an abstraction, the more they will scorn an actual one they meet. - Jean-Louis Rheault

The risk characteristic of a centralized system is different from that of a messy municipally-led confederation. The second type is stable in the long run because of some dose of volatility. 

Stability is not good for the economy: firms become very weak during long periods of steady prosperity devoid of setbacks, and hidden vulnerabilities accumulate silently under the surface - so delaying crises is not a very good idea. Likewise, absence of fluctuations in the market causes hidden risks to accumulate with impunity. The longer one goes without a market trauma, the worse the damage when commotion occurs. 

When a market reaches a “new low,” that is, drops to a level not seen in a long time, there is “a lot of blood” to come, with people rushing to the exit. Some people unused to losing shekels will be experiencing a large loss and will incur distress. If such a low market level has not been seen in years, say two years, it will be called “a two-year low” and will cause more damage than a one-year low. Tellingly, they call it a “cleanup,” getting the “weak hands” out of the way. A “weak hand” is clearly someone who is fragile but doesn’t know it and is lulled by a false sense of security. When many such weak hands rush to the door, they collectively cause crashes. A volatile market doesn’t let people go such a long time without a “cleanup” of risks, thereby preventing such market collapses. Fluctuat nec mergitur (fluctuates, or floats, but does not sink) goes the Latin saying.

Preventing randomness is an antifragile system isn to always a good idea. 

Consider the method of annealing in metallurgy, a technique used to make metal strong and more homogeneous. It involves the heating and controlled cooling of a material, to increase the size of the crystals and reduce their defects. The heat causes the atoms to become unstuck from their initial positions and wander randomly through states of higher energy; the cooling gives them more chances of finding new, better configurations. 

Mathematicians use a method of computer simulation called simulated annealing to bring more general optimal solutions to problems and situations, solutions that only randomness can deliver.

The so-called chaotic systems, those experiencing a brand of variations called chaos, can be stabilized by adding randomness to them. 

Experiments show that alertness is weakened when one relinquishes control to the system (again, lack of overcompensation).

In retrospect, it turned out to be a very effective strategy, not so much as a way to achieve their objectives, but rather to accommodate the fact that these objectives are moving targets. Procrastination turned out to be a way to let events take their course and give the activists the chance to change their minds before committing to irreversible policies.

Few understand that procrastination is our natural defense, letting things take care of themselves and exercise their antifragility; it results from some ecological or naturalistic wisdom, and it not always bad - at an existential level, it is my body rebelling against its entrapment. It is my soul fighting the Procrustean bed of modernity. Granted, in the modern world, my tax return is not going to take care of itself - but by delaying a non-vital visit to a doctor, or deferring the writing of a passage until my body tells me that I am ready for it, I may be using a very potent naturalistic filter. I write only if I feel like it and only on a subject I feel like writing about - and the reader is no fool. So I use procrastination as a message from my inner self and my deep evolutionary past to resist interventionism in my writing. 

Noise is what you are supposed to ignore, signal what you need to heed.

We are not made to understand the point, so we overreact emotionally to noise. The best solution is to only look at very large changes in data or conditions, never at small ones.

It is almost impossible for someone rational, with a clear, uninfected mind, someone who is not drowning in data, to mistake a vital signal, one that matters for his survival, for noise - unless he is overanxious, oversensitive, and neurotic, hence distracted and confused by other messages. Significant signals have a way to reach you. 

There are ample empirical findings to the effect that providing someone with a random numerical forecast increases his risk taking, even if the person knows the projections are random. 

Since detecting (anti)fragility is easier, must easier, than prediction and understanding the dynamics of events, the entire mission reduces to the central principle of what to do to minimize harm (and maximize gain) from forecasting errors, that is, to have things that don’t fall apart, or even benefit, when we make a mistake. 

A system built on illusions of understanding probability is bond to collapse.

By betting against fragility, they were antifragile.

A man is honorable in proportion to the personal risks he takes for his opinion - in other words, the amount of downside he is exposed to.

You can’t predict in general, but you can predict that those who rely on predictions are taking more risks, will have some trouble, perhaps even go bust. Why? Someone who predicts will be fragile to prediction errors. An overconfident pilot will eventually crash the plane. And numerical prediction leads people to take more risks. Fat Tony is antifragile because he takes a mirror image of his fragile prey. He identifies fragilities, makes a bet on the collapse of the fragile unit.

Wisdom in decision making is vastly more important - not just practically, but philosophically - than knowledge. 

Seneca’s oeuvre is nihil perditi, “I lost nothing,” after an adverse event. Stoicism makes you desire the challenge of a calamity. 

If wealth is so much of a burden, while unnecessary, what’s the point of having it?

Success brings an asymmetry: you now have a lot more to lose than to gain. You are hence fragile. Let us return to the story of Damocles’ sword. There is no good news in store, just plenty of bad news in the pipeline. When you become rich, the pain of losing your fortune exceeds the emotional gain of getting additional wealth, so you start living under continuous emotional threat. A rich person becomes trapped by belongings that take control of him, degrading his sleep at night, raising the serum concentration of his stress hormones, diminishing his sense of humor, perhaps even causing air to grow on the top of his noise and similar ailments. Seneca fathomed that possessions make us worry about downside, thus acting as a punishment as we depend on them. All upside, no downside. Even more: dependence on circumstances - rather, the emotions that arise from circumstances - induces a form of slavery. 

Men feel the good less intensely than the bad (segnius homies bona quam mala sentiunt)

Seneca’s practical method to counter such fragility was to go through mental exercises to write off possessions, so when losses occurred he would not feel the sting - a way to wrest one’s freedom from circumstances. 

An intelligent life is all about such emotional positioning to eliminate the sting of harm, which as we saw is done by mentally writing off belongings so one does not feel any pain from losses. The volatility of the world no longer affects you negatively. 

Stoicism is about the domestication, not necessarily the elimination, of emotions. My idea of the modern Stoic sage is someone who transforms fear into prudence, pain into information, mistakes into imitation, and desire into undertaking.

Wealth is the slave of the wise man and master of the fool.

…more to lose from adversity. If you have more to lose than to benefit from events of fate, there is an asymmetry, and not a good one. 

The antifragile package has more to gain than to lose from being shaken. Simple test: if I have “nothing to lose” then it is all gain and I am antifragile. 

To see why asymmetric payoffs like volatility, just consider that if you have less to lose than to gain, more upside than downside, then you like volatility (it will, on balance, bring benefits), and you are also antifragile. 

Fragility implies more to lose than to gain, equals more downside than upside, equals (unfavorable) asymmetry. 

Antifragility implies more to gain than to lose, equals more upside than downside, equals (favorable) asymmetry. 

You are antifragile for a source of volatility if potential gains exceed potential losses (and vice versa). Further, if you have more upside than downside, then you may be harmed by lack of volatility and stressors.

The first step towards antifragility consists in first decreasing downside, rather than increasing upside; that is, by lowering exposure to negative Black Swans and letting natural antifragility work by itself.

More upside than downside can come simply from the reduction of extreme downside (emotional harm) rather than improving things in the middle.

Overcompensation, to work, requires some harm and stressors as tools of discovery. It means letting children play a little bit, not much more than a little bit, with fire and learn from injuries, for the sake of their own future safety. It also means letting people experience some, not too much, stress, to wake them up a bit. But, at the same time, they need to be protected from high danger - ignore small dangers, invest your energy in protecting them from consequential harm. And only consequential harm. This can visibly be translated into social policy, health care, and many more matters. 

“Provide for the worst; the best can take of itself.”

This is what Seneca elected to do: he initially had a very active, adventurous life, followed by a philosophical withdrawal to write and meditate, rather than a “middle” combination of both. Many of the “doers” turned “thinkers” like Montaigne have done a serial barbell: pure action, then pure reflection. Or, if I have to work, I find it preferable (and less painful) to work intensely for very short hours, then do nothing for the rest of the time (assuming doing nothing is really doing nothing), until I recover completely and look forward to a repetition, rather than being subjected to the tedium of Japanese style low-intensity interminable office hours with sleep deprivation. Main course and dessert are separate. 

The legendary investor Ray Dalio has a rule for someone making speculative bets: “Make sure that the probability of the unacceptable (i.e., the risk of ruin) is nil.” Such a rule gets one straight to the barbell.

The barbell is simple an idea of insurance of survival; it is a necessity, not an option. 

The rational flaneur is someone who, unlike a tourist, makes a decision at every step to revise his schedule, so he can imbibe things based on new information. The flaneur is not a prisoner of a plan. Tourism, actual or figurative, is imbued with the teleological illusion; it assumes completeness of vision and gets one locked into a hard-to-revise program, while the flaneur continuously - and, what is crucial, rationally - modifies his targets as he acquires information. Now a warning: the opportunism of the flaneur is great in life and business - but not in personal life and matters that involve others. The opposite of opportunism in human relations is loyalty, a noble sentiment - but one that needs to be invested int he right places, that is, in human relationships and moral commitments. 

Never ask people what they want, or where they want to go, or where they think they should go, or, worse, what they think they will desire tomorrow. The strength of the computer entrepreneur Steve Jobs was precisely in distrusting market research and focus groups - those based on asking people what they want - and following his own imagination. His modus was that people don’t know what they want until you provide them with it. This ability to switch from a course of action is an option to change. Optionality will take us many places, but at the core, an option is what makes you antifragile and allows you to benefit from the positive side of uncertainty, without a corresponding serious harm from the negative side. 

America’s asset is, simply, risk taking and the use of optionality, this remarkable ability to engage in rational forms of trial and error, with no comparative shale in failing, starting again, and repeating failure. 

A sum large enough to get most, if not all, of the advantages of wealth (the most important one being independence and the ability to only occupy your mind with matters that interest you) but not its side effects.

Simply, he had a contract that is the archetype of what an asymmetry is, perhaps the only explicit asymmetry you can find in its purest form. It is an option, “the right but not the obligation” for the buyer and, of course, “the obligation but not the right” for the other party had the obligation, not the right. Thales paid a small price for that privilege, with a limited loss and large possible outcome. That was the very first option on record. The option is an agent of antifragility. 

Antifragility equals more to gain than to lose equals more upside than downside equals asymmetry (unfavorable) equals like volatility. And if you make more when you are right than you are hurt when you are wrong then you will benefit, in the long run, from volatility (and the reverse). You are only harmed if you repeatedly pay too much for the option. 

Financial independence, when used intelligently, can make you robust: it gives you options and allows you to make the right choices. Freedom is the ultimate option. 

Options, any options, by allowing you more upside than downside, are vectors of antifragility. 

I have an option, not an obligation.

So consider the asymmetry. You benefit from lower rents, but are not hurt by higher ones. How? Because here again, you have an option, not an obligation. IN a way, uncertainty increases the worth of such privilege. Should you face a high degree of uncertainty about future outcomes, with possible huge decreases in real estate value, or huge possible increases in them, your option would become more valuable. The more uncertainty, the more valuable the option.

One property of the option: it does not care about the average outcome, only the favorable ones (since the downside doesn’t count beyond a certain point). Authors, artists, and even philosophers are much better off having a very small number of fanatics behind them than a large number of people who appreciate their work. 

Your work and ideas, whether in politics, the arts, or other domains, are antifragile if, instead of having one hundred percent of the people finding your mission acceptable or mildly commendable, you are better off having a high percentage of people dispelling you and your message (even intensely), combined with a low percentage of extremely loyal and enthusiastic supporters. Options like dispersion of outcomes and don’t care about the average too much.

You don’t have to be right that often. All you need is the wisdom to not do unintelligent things to hurt yourself (some acts of mission) and recognize favorable outcomes when they occur. (The key is that your assessment doesn’t need to be made beforehand, only after the outcome.)

The fragile has no option. But the antifragile needs to select what’s best - the best option. 

Options benefit from variability, but also from situations in which errors carry small costs. So these errors are like options - in the long run, happy errors bring gains, unhappy errors bring losses.

If you list the businesses that have generated the most wealth in history, you would see that they all have optionality. 

The largest generators of wealth in America historically have been, first, real estate (investors have the option at the expense of the banks), and, second, technology (which relies almost completely on trial and error). Further, businesses with negative optionality (that is, the opposite of have optionality) such as banking have had a horrible performance through history: banks lose periodically every penny made in their history thanks to blowups. 

Just as great geniuses invent their predecessors, practical innovations create their theatrical ancestry. 

We play down the role of ache, especially when it comes to our own discoveries. 

Implementation does not necessarily proceed from invention. It, too, requires luck and circumstances. Just taking something to market requires struggling against a collection of naysayers, administrators, empty suits, formalists, mountains of details that invite you to drown, and one’s own discouraged mood on occasion. In other words, to identify the option (again, there is this option blindness). This is where all you need is the wisdom to realize what you have on your hands. 

Sometimes you need a visionary to figure out what to do with a discovery, a vision that he and only he can have. 

The simplest “technologies,” or perhaps not even technologies but tools, such as the wheel, are the ones that seem to run the world. 

Trial and error has one overriding value people fail to understand: it is not really random, rather, thanks to optionality, it requires some rationality. One needs to be intelligent in recognizing the favorable outcome and knowing what to discard. 

In many pursuits, every trial, every failure provides additional information, each more valuable than the previous one. With every trial one gets closer to something, assuming an environment in which one knows exactly what one is looking for. We can, from the trial that fails to deliver, figure out progressively where to go. 

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.

Sophistication is born of need, and success of difficulties. 

“Poverty makes experiences” (hominem experiri multa paupertas iubet)

People with too much smoke and complicated tricks and methods in their brains start missing elementary, very elementary things. I saw the less is more in action: the more studies, the less obvious elementary but fundamental things become; activity, on the other hand, strips things to their simplest possible model.

An idea does not survive because it is better than the competition, but rather because the person who holds it has survived!

They owed nothing to science; they were empirical developments based on the trial, error, and experimentation of skilled craftsmen who were trying ti improve the productivity, and so the profits, of their factories.

Visibly the money should go to the tinkerers, the aggressive tinkerers who you trust will milk the option.

Look for optionality; in fact, rank things according to optionality, preferably with open-ended, not closed-ended, payoffs. Do not invest in business plans but in people, so look for someone capable of changing six or seven times over his career, or more; one gets immunity from the backlit narratives of the business plan by investing in people. It is simply more robust to do so. Make sure you are barreled, whatever that means in your business. 

Soccer moms try to eliminate the trial and error, the antifragility, from children’s lives, move them away from the ecological and transform them into nerds working on preexisting maps of reality. I believe that one can be an intellectual without being a nerd, provided one has a private library instead of a classroom, and spends time as an aimless (but rational) flaneur benefiting from what randomness can give us inside and outside the library. Provided we have the right type of rigor, we need randomness, mess, adventures, uncertainty, self-discovery, near-traumatic episodes, all these things that make life worth living, compared to the structured, fake, and ineffective life of an empty-suit CEO with a preset schedule and an alarm clock. It is as if the mission of modernity was to squeeze every drop of variability and randomness out of life - with the ironic result of making the world a lot more unpredictable, as if the goddesses of chance wanted to have the last word. Only the autodidacts are free. And not just in school matters - those who decommoditize, detouristify their lives. 

The trick is to be bored with a specific book, rather than with the act of reading. So the number of pages absorbed could grow faster than otherwise. And you find gold, so to speak, effortlessly, just as in rational but undirected trial-and-error-based research.

Socrates’ technique was to make his interlocutor, who started with a thesis, agree to a series of statements, then proceed to show him how the statements he agreed to are inconsistent wit the original thesis, thus establishing that he has no clue as to what he was talking about. Socrates used it mostly to show people how lacking in clarity they were in their thoughts, how little they knew about the concepts they used routinely - and the need for philosophy to elucidate these concepts.

Both dislike writing: Socrates because he did not like the definitive and immutable character that is associated with the written word when for him answers are never final and should not be fixed. Nothing should be written in stone, even literally. 

What is not intelligible to me is not necessarily unintelligent.

Exposure is more important than knowledge; decision effects supersedes logic. 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.

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

The difference between a thousand pebbles and a large stone of equivalent weight is a potent illustration of how fragility stems from nonlinear effects. Nonlinear? Once again, “nonlinear” means that the response is not straightforward and not a straight line, so if you double, say, the dose, you get a lot more or a lot less than double the effect - if I throw at someone’s head a ten-pound stone, more than five times the harm of a one-pound stone, etc. It is simple: if you draw a line on a graph, with harm on the vertical axis and the size of the stone on the horizontal axis, it will be curved, not a straight line. That is a refinement of asymmetry. 

For the fragile, shocks bring higher harm as their intensity increases (up to a certain level).

Asymmetry is necessarily nonlinearity. More harm than benefits: simply, an increase in intensity brings more harm than a corresponding decrease offers benefits. 

We are necessarily immune to the cumulative effect of small deviations, or shocks of very small magnitude, which implies that these affect us disproportionately less (that is, nonlinearly less) than larger ones.

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

The principle that the fragile is what is hurt a lot more by extreme events than by a succession of intermediates ones. 

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

Nonlinearity comes in two kinds: concave (curves inward), or its opposite, convex (curves outward). And of course, mixed, with concave and convex section. 

If you earn more than you lose from fluctuations, you want a lot of fluctuations. 

Many economic results are completely canceled by convexity effects.

This is the central problem of efficiency: these types of errors compound, multiply, swell, with an effect that only goes in one direction - the wrong direction. 

In spite of what is studied in business schools concerning “economies of scale,” size hurts you at times of stress; it is not a good idea to be large during difficult times. 

Always keep in mind the difference between a stone and its weight in pebbles.

When you add uncertainty to projects, they tend to cost more and take longer to complete. This applies to many, in fact almost all, projects.

The hidden benefits of antifragility is that you can guess worse than random and still end up outperforming. Here lies the power of optionality - your function of something is very convex, so you can be wrong and still do fine - the more uncertainty, the better. 

Charlatans are recognizable in that they will give you positive advice, and only positive advice, exploiting our gullibility and sucker-proneness for recipes that hit you in a flash as just obvious, then evaporate later as you forget them. You 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. 

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). So knowledge grows by subtraction much more than by addition - given that what we know today might turn out to be wrong but what we know to be wrong cannot turn out to be right at least not easily. 

“People think focus means saying yes to the thing you’ve got to focus on. But that’s not what it means at all. It means saying no to the hundred other good ideas that there are. You have to pick carefully. I’m actually as proud of the things we haven’t done as the things I have done. Innovation is saying no to 1,000 things.” - Steve Jobs

Obvious decisions (robust to error) require no more than a single reason.

A philosopher should be known for one single idea, not more.

For the perishable, every additional day in its life translates into a shorter additional life expectancy. For the nonperishable, every additional day may imply a longer life expectancy. 

The robustness of an item is proportional to its life.

The Lindy effect, says, mathematically, that the nonperishable has a life expectancy that increases with every day it survives.

Much progress comes from the young because of their relative freedom from the system and courage to take action that older people lose as they become trapped in life. But it is precisely the young who propose ideas that are fragile, not because they are young, but because most unseasoned ideas are fragile.

How could we teach children skills for the twenty-first century when we do not know which skills will be needed in the twenty-first century? By making them read the classics. The future is in the past. 

He who does not have a past has no future.

Information has a nasty property: it hides failures. 

A mile, from the Latin milia passum, is a thousand paces. Likewise a stone (14 pounds) corresponds to . . . well, a stone. An inch(or pounce) corresponds to a thumb. A furlong is the distance one can sprint before running out of breath. A pound, from libra, is what you can imagine holding in your hands.

If there is something in nature you don’t understand, odds are it makes sense in a deeper way that is beyond your understanding. So there is a logic to natural things that is much superior to our own. What Mother Nature does is rigorous until proven otherwise; what humans and science do is flawed until proven otherwise. 

When the (present) inhabitants of Mother Earth want to do something counter to nature, they are the ones that need to product the evidence, if they can. Everything constable or breakable has had ample chance to break over time. Further, the interactions between components of Mother Nature had to modulate in such a way as to keep the overall system alive. What emerges over millions of years is a wonderful combination of solidity, antifragility, and local fragility, sacrifices in one area made in order for nature to function better. 

Random variability is often mistaken for information, hence leading to intervention. 

Spend less, live longer is a subtractive strategy. 

Subtraction of a substance not seasoned by our evolutionary history reduces the possibility of Black Swans while leaving one open to improvements. Should the improvements occur, we can be pretty comfortable that they are as free of unseen side effects as one can get. 

For the ancients, the worst possible outcome was not death, but dishonorable death, or even just a regular one. 

While the gene is antifragile, since it is information, the carrier of the gene is fragile, and needs to be so for the gene to get stronger. We live to produce information, or improve on it.

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.

Never ask anyone for their opinion, forecast, or recommendation. Just ask them what they have - or don’t have - in their portfolio. 

Never put your enemy’s back to the wall.

For the ancients, someone in debt was not free, he was in bondage.

The definition of the free man, according to Aristotle, is one who is free with his opinions - as a side effect of being free with his time.

People fit their beliefs to actions rather than fit their actions to their beliefs.

Everything gains or loses from volatility. Fragility is what loses from volatility and uncertainty.