Noise A Flaw in Human Judgment by Sunstein, Cass R. Sibony, Olivier Kahneman, Daniel [Sunstein, Cass R.]

 Noise A Flaw in Human Judgment by Sunstein, Cass R.  Sibony, Olivier  Kahneman, Daniel [Sunstein, Cass R.] 

This book comes in six parts. In part 1, we explore the difference between noise and bias. In part 2, we investigate the nature of human judgment and explore how to measure accuracy and error. Part 3 takes a deeper look at one type of judgment that has been researched extensively: predictive judgment. Part 4 turns to human psychology. We explain the central causes of noise. These include interpersonal differences arising from a variety of factors Part 5 explores the practical question of how you can improve your judgments and prevent error. What is the right level of noise? Part 6 turns to this question. 

Judgment can therefore be described as a measurement in which the instrument is a human mind. Implicit in the notion of measurement is the goal of accuracy—to approach truth and minimize error. The goal of judgment is not to impress, not to take a stand, not to persuade.

Level noise is when judges show different levels of severity. Pattern noise is when they disagree with one another on which defendants deserve more severe or more lenient treatment. And part of pattern noise is occasion noise—when judges disagree with themselves.

In a perfect world, defendants would face justice; in our world, they face a noisy system.

Bullshit has become something of a technical term since Harry Frankfurt, a philosopher at Princeton University, published an insightful book, On Bullshit, in which he distinguished bullshit from other types of misrepresentation.

When people are introduced to clinical and mechanical prediction, they want to know how the two compare. How good is human judgment, relative to a formula?

The question had been asked before, but it attracted much attention only in 1954, when Paul Meehl, a professor of psychology at the University of Minnesota, published a book titled Clinical Versus Statistical Prediction: A Theoretical Analysis and a Review of the Evidence. Meehl reviewed twenty studies in which a clinical judgment was pitted against a mechanical prediction for such outcomes as academic success and psychiatric prognosis. He reached the strong conclusion that simple mechanical rules were generally superior to human judgment. Meehl discovered that clinicians and other professionals are distressingly weak in what they often see as their unique strength: the ability to integrate information.

When there is a lot of data, machine-learning algorithms will do better than humans and better than simple models. But even the simplest rules and algorithms have big advantages over human judges: they are free of noise, and they do not attempt to apply complex, usually invalid insights about the predictors.

AI often performs better than simpler models do. In most applications, however, its performance remains far from perfect.

Wherever there is prediction, there is ignorance, and probably more of it than we think.

When you trust your gut because of an internal signal, not because of anything you really know, you are in denial of your objective ignorance

Models do better than people, but not by much. Mostly, we find mediocre human judgments and slightly better models. Still, better is good, and models are better.

Among doctors, the level of noise is far higher than we might have suspected. In diagnosing cancer and heart disease—even in reading X-rays—specialists sometimes disagree. That means that the treatment a patient gets might be a product of a lottery.

Doctors like to think that they make the same decision whether it’s Monday or Friday or early in the morning or late in the afternoon. But it turns out that what doctors say and do might well depend on how tired they are.

Medical guidelines can make doctors less likely to blunder at a patient’s expense. Such guidelines can also help the medical profession as a whole because they reduce variability.

In traditional, informal interviews, we often have an irresistible, intuitive feeling of understanding the candidate and knowing whether the person fits the bill. We must learn to distrust that feeling.

Traditional interviews are dangerous not only because of biases but also because of noise.

We must add structure to our interviews and, more broadly, to our selection processes. Let’s start by defining much more clearly and specifically what we are looking for in candidates, and let’s make sure we evaluate the candidates independently on each of these dimensions.

There are seven major objections to efforts to reduce or eliminate noise.

• First, reducing noise can be expensive; it might not be worth the trouble. The steps that are necessary to reduce noise might be highly burdensome. In some cases, they might not even be feasible.

• Second, some strategies introduced to reduce noise might introduce errors of their own. Occasionally, they might produce systematic bias. If all forecasters in a government office adopted the same unrealistically optimistic assumptions, their forecasts would not be noisy, but they would be wrong. If all doctors at a hospital prescribed aspirin for every illness, they would not be noisy, but they would make plenty of mistakes.

• Third, if we want people to feel that they have been treated with respect and dignity, we might have to tolerate some noise. Noise can be a by-product of an imperfect process that people end up embracing because the process gives everyone (employees, customers, applicants, students, those accused of crime) an individualized hearing, an opportunity to influence the exercise of discretion, and a sense that they have had a chance to be seen and heard.

• Fourth, noise might be essential to accommodate new values and hence to allow moral and political evolution. If we eliminate noise, we might reduce our ability to respond when moral and political commitments move in new and unexpected directions. A noise-free system might freeze existing values.

• Fifth, some strategies designed to reduce noise might encourage opportunistic behavior, allowing people to game the system or evade prohibitions. A little noise, or perhaps a lot of it, might be necessary to prevent wrongdoing.

• Sixth, a noisy process might be a good deterrent. If people know that they could be subject to either a small penalty or a large one, they might steer clear of wrongdoing, at least if they are risk-averse. A system might tolerate noise as a way of producing extra deterrence.

• Finally, people do not want to be treated as if they are mere things or cogs in some kind of machine. Some noise-reduction strategies might squelch people’s creativity and prove demoralizing.

People value and even need face-to-face interactions. They want real human being to listen to their concerns and complaints and to have the power to make things better. Sure, those interactions will inevitably produce noise. But human dignity is priceless.

Moral values are constantly evolving. If we lock everything down, we won’t make space for changing values. Some efforts to reduce noise are just too rigid; they would prevent moral change.

If you want to deter misconduct, you should tolerate some noise. If students are left wondering about the penalty for plagiarism, great—they will avoid plagiarizing. A little uncertainty in the form of noise can magnify deterrence.

If we eliminate noise, we might end up with clear rules, which wrongdoers will find ways to avoid. Noise can be a price worth paying if it is a way of preventing strategic or opportunistic behavior.

Creative people need space. People aren’t robots. Whatever your job, you deserve some room to maneuver. If you’re hemmed in, you might not be noisy, but you won’t have much fun and you won’t be able to bring your original ideas to bear.

In the end, most of the efforts to defend noise aren’t convincing. We can respect people’s dignity, make plenty of space for moral evolution, and allow for human creativity without tolerating the unfairness and cost of noise.

Rules simplify life and reduce noise. But standards allow people to adjust to the particulars of the situations.

Rules or standards? First, ask which produces more mistakes. Then, ask which is easier or more burdensome to produce or work with.

We often use standards when we should embrace rules—simply because we don’t pay attention to the noise.

Noise reduction shouldn’t be part of the Universal Declaration of Human Rights—at least not yet. Still, noise can be horribly unfair. All over the world, legal systems should consider taking strong steps to reduce it.

Type of noises:

System noise can be broken down into level noise and pattern noise. Some judges are generally more severe than others, and others are more lenient; some forecasters are generally bullish and others bearish about market prospects; some doctors prescribe more antibiotics than others do. Level noise is the variability of the average judgments made by different individuals. The ambiguity of judgment scales is one of the sources of level noise. Words such as likely or numbers (e.g., 4 on a scale of 0 to 6) mean different things to different people. Level noise is an important source of error in judgment systems and an important target for interventions aimed at noise reduction.

System noise includes another, generally larger component. Regardless of the average level of their judgments, two judges may differ in their views of which crimes deserve the harsher sentences. Their sentencing decisions will produce a different ranking of cases. We call this variability pattern noise (the technical term is statistical interaction ).

The main source of pattern noise is stable: it is the difference in the personal, idiosyncratic responses of judges to the same case. Some of these differences reflect principles or values that individuals follow, whether consciously or not. 

pattern noise also has a transient component, called occasion noise. We detect this kind of noise if a radiologist assigns different diagnoses to the same image on different days or if a fingerprint examiner identifies two prints as a match on one occasion but not on another

The judges’ cognitive flaws are not the only cause of errors in predictive judgments. Objective ignorance often plays a larger role. 

Psychological biases are, of course, a source of systematic error, or statistical bias. Less obviously, they are also a source of the noise. When biases are not shared by all judges, when they are present to different degrees, and when their effects depend on extraneous circumstances, psychological biases produce noise. 

How to Reduce Noise (and Bias, Too)

There is reason to believe that some people make better judgments than others do. Task-specific skill, intelligence, and a certain cognitive style—best described as being actively open-minded —characterize the best judges. Unsurprisingly, good judges will make few egregious mistakes. Given the multiple sources of individual differences, however, we should not expect even the best judges to be in perfect agreement on complex judgment problems. The infinite variety of backgrounds, personalities, and experiences that make each of us unique is also what makes noise inevitable.

One strategy for error reduction is debiasing. Typically, people attempt to remove bias from their judgments either by correcting judgments after the fact or by taming biases before they affect judgments. 

Our main suggestion for reducing noise in judgment is decision hygiene. We chose this term because noise reduction, like health hygiene, is prevention against an unidentified enemy. 

A noise-reduction effort in an organization should always begin with a noise audit (see appendix A). An important function of the audit is to obtain a commitment of the organization to take noise seriously. An essential benefit is the assessment of separate types of noise.

We now recapitulate six principles that define decision hygiene, describe how they address the psychological mechanisms that cause noise, and show how they relate to the specific decision hygiene techniques we have discussed

1. The goal of judgment is accuracy, not individual expression.

2. Think statistically, and take the outside view of the case 

3. Structure judgments into several independent tasks.

4. Resist premature intuitions

5. Obtain independent judgments from multiple judges, then consider aggregating those judgments.

6. Favor relative judgments and relative scales

Bias leads to errors and unfairness. Noise does too—and yet, we do a lot less about it. Judgment error may seem more tolerable when it is random than when we attribute it to a cause, but it is no less damaging. If we want better decisions about things that matter, we should take noise reduction seriously.

Think again by Adam Grant

 Think again by Adam Grant

When people reflect on what it takes to be mentally fit, the first idea that comes to mind is usually intelligence. The smarter you are, the more complex the problems you can solve—and the faster you can solve them. Intelligence is traditionally viewed as the ability to think and learn. Yet in a turbulent world, there’s another set of cognitive skills that might matter more: the ability to rethink and unlearn.

Some psychologists point out that we’re mental misers: we often prefer the ease of hanging on to old views over the difficulty of grappling with new ones. Yet there are also deeper forces behind our resistance to rethinking. Questioning ourselves makes the world more unpredictable. It requires us to admit that the facts may have changed, that what was once right may now be wrong.

A hallmark of wisdom is knowing when it’s time to abandon some of your most treasured tools—and some of the most cherished parts of your identity.

With advances in access to information and technology, knowledge isn’t just increasing. It’s increasing at an increasing rate. 

Researchers have recently discovered that we need to rethink widely accepted assumptions about such subjects as Cleopatra’s roots (her father was Greek, not Egyptian, and her mother’s identity is unknown); the appearance of dinosaurs (paleontologists now think some tyrannosaurs had colorful feathers on their backs); 

Vintage records, classic cars, and antique clocks might be valuable collectibles, but outdated facts are mental fossils that are best abandoned.

As we think and talk, we often slip into the mindsets of three different professions: preachers, prosecutors, and politicians. In each of these modes, we take on a particular identity and use a distinct set of tools. We go into preacher mode when our sacred beliefs are in jeopardy: we deliver sermons to protect and promote our ideals. We enter prosecutor mode when we recognize flaws in other people’s reasoning: we marshal arguments to prove them wrong and win our case. We shift into politician mode when we’re seeking to win over an audience: we campaign and lobby for the approval of our constituents. The risk is that we become so wrapped up in preaching that we’re right, prosecuting others who are wrong, and politicking for support that we don’t bother to rethink our own views.

If you’re a scientist by trade, rethinking is fundamental to your profession. You’re paid to be constantly aware of the limits of your understanding. You’re expected to doubt what you know, be curious about what you don’t know, and update your views based on new data. 

Mental horsepower doesn’t guarantee mental dexterity. No matter how much brain power you have, if you lack the motivation to change your mind, you’ll miss many opportunities to think again.

In psychology, there are at least two biases that drive this pattern. 

• One is confirmation bias: seeing what we expect to see. 

• The other is desirability bias: seeing what we want to see. 

These biases don’t just prevent us from applying our intelligence. They can actually contort our intelligence into a weapon against the truth. We find reasons to preach our faith more deeply, prosecute our case more passionately, and ride the tidal wave of our political party. The tragedy is that we’re usually unaware of the resulting flaws in our thinking.

Thinking like a scientist involves more than just reacting with an open mind. It means being actively open-minded. It requires searching for reasons why we might be wrong—not for reasons why we must be right—and revising our views based on what we learn.

The legend of Apple’s renaissance revolves around the lone genius of Steve Jobs. It was his conviction and clarity of vision, the story goes, that gave birth to the iPhone. The reality is that he was dead-set against the mobile phone category. His employees had the vision for it, and it was their ability to change his mind that really revived Apple. Although Jobs knew how to think different, it was his team that did much of the rethinking.

The curse of knowledge is that it closes our minds to what we don’t know. Good judgment depends on having the skill—and the will—to open our minds.

Arrogance is ignorance plus conviction, blogger Tim Urban explains. While humility is a permeable filter that absorbs life experience and converts it into knowledge and wisdom, arrogance is a rubber shield that life experience simply bounces off of.

One of the Latin roots of humility means from the earth. It’s about being grounded—recognizing that we’re flawed and fallible

In a classic paper, sociologist Murray Davis argued that when ideas survive, it’s not because they’re true—it’s because they’re interesting. What makes an idea interesting is that it challenges our weakly held opinions. 

Who you are should be a question of what you value, not what you believe. Values are your core principles in life—they might be excellence and generosity, freedom and fairness, or security and integrity. Basing your identity on these kinds of principles enables you to remain open-minded about the best ways to advance them. 

People who are right a lot listen a lot, and they change their minds a lot, Jeff Bezos says. If you don’t change your mind frequently, you’re going to be wrong a lot.

There are times when preaching and prosecuting can make us more persuasive. Research suggests that the effectiveness of these approaches hinges on three key factors: how much people care about the issue, how open they are to our particular argument, and how strong-willed they are in general. If they’re not invested in the issue or they’re receptive to our perspective, more reasons can help: people tend to see quantity as a sign of quality. The more the topic matters to them, the more the quality of reasons matters. It’s when audiences are skeptical of our view, have a stake in the issue, and the quality of reasons matters. It’s when audiences are skeptical of our view, have a stake in the issue, and tend to be stubborn that piling on justifications is most likely to backfire. If they’re resistant to rethinking, more reasons simply give them more ammunition to shoot our views down

Motivational interviewing starts with an attitude of humility and curiosity. 

The process of motivational interviewing involves three key techniques:

1. Asking open-ended questions

2. Engaging in reflective listening

3. Affirming the person’s desire and ability to change

In a series of experiments, interacting with an empathetic, nonjudgmental, attentive listener made people less anxious and defensive. They felt less pressure to avoid contradictions in their thinking, which encouraged them to explore their opinions more deeply, recognize more nuances in them, and share them more openly. 

These benefits of listening aren’t limited to one-on-one interactions—they can also emerge in groups. Psychologists recommend practicing this skill by sitting down with people whom we sometimes have a hard time understanding. The idea is to tell them that we’re working on being better listeners, we’d like to hear their thoughts, and we’ll listen for a few minutes before responding.

And experiments have shown that when a speaker delivers an inspiring message, the audience scrutinizes the material less carefully and forgets more of the content—even while claiming to remember more of it. 

Social scientists have called this phenomenon the awestruck effect, but I think it’s better described as the dumbstruck effect. The sage-on-the-stage often preaches new thoughts, but rarely teaches us how to think for ourselves. Thoughtful lecturers might prosecute inaccurate arguments and tell us what to think instead, but they don’t necessarily show us how to rethink moving forward. Charismatic speakers can put us under a political spell, under which we follow them to gain their approval or affiliate with their tribe. We should be persuaded by the substance of an argument, not the shiny package in which it’s wrapped.

There’s only one class I regret missing in college. It was taught by a philosopher named Robert Nozick. One of his ideas became famous thanks to the movie The Matrix:

Lectures are not always the best method of learning, and they are not enough to develop students into lifelong learners. 

It’s been demonstrated repeatedly that one of the best ways to learn is to teach.

Psychologists find that the more people value happiness, the less happy they often become with their lives. 

• One possibility is that when we’re searching for happiness, we get too busy evaluating life to actually experience it. Instead of savoring our moments of joy, we ruminate about why our lives aren’t more joyful. 

• A second likely culprit is that we spend too much time striving for peak happiness, overlooking the fact that happiness depends more on the frequency of positive emotions than their intensity. 

• A third potential factor is that when we hunt for happiness, we overemphasize pleasure at the expense of purpose. This theory is consistent with data suggesting that meaning is healthier than happiness and that people who look for purpose in their work are more successful in pursuing their passions—and less likely to quit their jobs—than those who look for joy. While enjoyment waxes and wanes, meaning tends to last. 

• A fourth explanation is that Western conceptions of happiness as an individual state leave us feeling lonely. In more collectivistic Eastern cultures, that pattern is reversed: pursuing happiness predicts higher well-being because people prioritize social engagement over independent activities.

Psychologists find that passions are often developed, not discovered. In a study of entrepreneurs, the more effort they put into their startups, the more their enthusiasm about their businesses climbed each week. Their passion grew as they gained momentum and mastery. Interest doesn’t always lead to effort and skill; sometimes it follows them. By investing in learning and problem solving, we can develop our passions—and build the skills necessary to do the work and lead the lives we find worthwhile.

Our identities are open systems, and so are our lives. We don’t have to stay tethered to old images of where we want to go or who we want to be. The simplest way to start rethinking our options is to question what we do daily.

It takes humility to reconsider our past commitments, doubts to question our present decisions, and curiosity to reimagine our future plans. What we discover along the way can free us from the shackles of our familiar surroundings and our former selves. Rethinking liberates us to do more than update our knowledge and opinions—it’s a tool for leading a more fulfilling life.

Actions for Impact

If you’re interested in working on your rethinking skills, here are my top thirty practical takeaways.

I. INDIVIDUAL RETHINKING

A. Develop the Habit of Thinking Again

1. Think like a scientist. When you start forming an opinion, resist the temptation to preach, prosecute, or politick. Treat your emerging view as a hunch or a hypothesis and test it with data. Like the entrepreneurs who learned to approach their business strategies as experiments, you’ll maintain the agility to pivot.

2. Define your identity in terms of values, not opinions. It’s easier to avoid getting stuck to your past beliefs if you don’t become attached to them as part of your present self-concept. See yourself as someone who values curiosity, learning, mental flexibility, and searching for knowledge. As you form opinions, keep a list of factors that would change your mind.

3. Seek out information that goes against your views. You can fight confirmation bias, burst filter bubbles, and escape echo chambers by actively engaging with ideas that challenge your assumptions. An easy place to start is to follow people who make you think—even if you usually disagree with what they think.

B. Calibrate Your Confidence

4. Beware of getting stranded at the summit of Mount Stupid. Don’t confuse confidence with competence. The Dunning-Kruger effect is a good reminder that the better you think you are, the greater the risk that you’re overestimating yourself—and the greater the odds that you’ll stop improving. To prevent overconfidence in your knowledge, reflect on how well you can explain a given subject.

5. Harness the benefits of the doubt. When you find yourself doubting your ability, reframe the situation as an opportunity for growth. You can have confidence in your capacity to learn while questioning your current solution to a problem. Knowing what you don’t know is often the first step toward developing expertise.

6. Embrace the joy of being wrong. When you find out you’ve made a mistake, take it as a sign that you’ve just discovered something new. Don’t be afraid to laugh at yourself. It helps you focus less on proving yourself—and more on improving yourself.

C. Invite Others to Question Your Thinking

7. Learn something new from each person you meet. Everyone knows more than you about something. Ask people what they’ve been rethinking lately, or start a conversation about times you’ve changed your mind in the past year.

8. Build a challenge network, not just a support network. It’s helpful to have cheerleaders encouraging you, but you also need critics to challenge you. Who are your most thoughtful critics? Once you’ve identified them, invite them to question your thinking. To make sure they know you’re open to dissenting views, tell them why you respect their pushback—and where they usually add the most value.

9. Don’t shy away from constructive conflict. Disagreements don’t have to be disagreeable. Although relationship conflict is usually counterproductive, task conflict can help you think again. Try framing disagreement as a debate: people are more likely to approach it intellectually and less likely to take it personally.

II. INTERPERSONAL RETHINKING

A. Ask Better Questions

10. Practice the art of persuasive listening. When we’re trying to open other people’s minds, we can frequently accomplish more by listening than by talking. How can you show an interest in helping people crystallize their own views and uncover their own reasons for change? A good way to start is to increase your question-to-statement ratio.

11. Question how rather than why. When people describe why they hold extreme views, they often intensify their commitment and double down. When they try to explain how they would make their views a reality, they often realize the limits of their understanding and start to temper some of their opinions.

12. Ask What evidence would change your mind? You can’t bully someone into agreeing with you. It’s often more effective to inquire about what would open their minds, and then see if you can convince them on their own terms.

13. Ask how people originally formed an opinion. Many of our opinions, like our stereotypes, are arbitrary; we’ve developed them without rigorous data or deep reflection. To help people reevaluate, prompt them to consider how they’d believe different things if they’d been born at a different time or in a different place.

B. Approach Disagreements as Dances, Not Battles

14. Acknowledge common ground. A debate is like a dance, not a war. Admitting points of convergence doesn’t make you weaker—it shows that you’re willing to negotiate about what’s true, and it motivates the other side to consider your point of view.

15. Remember that less is often more. If you pile on too many different reasons to support your case, it can make your audiences defensive—and cause them to reject your entire argument based on its least compelling points. Instead of diluting your argument, lead with a few of your strongest points.

16. Reinforce freedom of choice. Sometimes people resist not because they’re dismissing the argument but because they’re rejecting the feeling of their behavior being controlled. It helps to respect their autonomy by reminding them that it’s up to them to choose what they believe.

17. Have a conversation about the conversation. If emotions are running hot, try redirecting the discussion to the process. Like the expert negotiators who comment on their feelings and test their understanding of the other side’s feelings, you can sometimes make progress by expressing your disappointment or frustration and asking people if they share it.

III. COLLECTIVE RETHINKING

A. Have More Nuanced Conversations

18. Complexify contentious topics. There are more than two sides to every story. Instead of treating polarizing issues like two sides of a coin, look at them through the many lenses of a prism. Seeing the shades of gray can make us more open.

19. Don’t shy away from caveats and contingencies. Acknowledging competing claims and conflicting results doesn’t sacrifice interest or credibility. It’s an effective way to engage audiences while encouraging them to stay curious.

20. Expand your emotional range. You don’t have to eliminate frustration or even indignation to have a productive conversation. You just need to mix in a broader set of emotions along with them—you might try showing some curiosity or even admitting confusion or ambivalence.

B. Teach Kids to Think Again

21. Have a weekly myth-busting discussion at dinner. It’s easier to debunk false beliefs at an early age, and it’s a great way to teach kids to become comfortable with rethinking. Pick a different topic each week—one day it might be dinosaurs, the next it could be outer space—and rotate responsibility around the family for bringing a myth for discussion.

22. Invite kids to do multiple drafts and seek feedback from others. Creating different versions of a drawing or a story can encourage kids to learn the value of revising their ideas. Getting input from others can also help them to continue evolving their standards. They might learn to embrace confusion—and to stop expecting perfection on the first try.

23. Stop asking kids what they want to be when they grow up. They don’t have to define themselves in terms of a career. A single identity can close the door to alternatives. Instead of trying to narrow their options, help them broaden their possibilities. They don’t have to be one thing—they can do many things.

C. Create Learning Organizations

24. Abandon best practices. Best practices suggest that the ideal routines are already in place. If we want people to keep rethinking the way they work, we might be better off adopting process accountability and continually striving for better practices.

25. Establish psychological safety. In learning cultures, people feel confident that they can question and challenge the status quo without being punished. Psychological safety often starts with leaders role-modeling humility.

26. Keep a rethinking scorecard. Don’t evaluate decisions based only on the results; track how thoroughly different options are considered in the process. A bad process with a good outcome is luck. A good process with a bad outcome might be a smart experiment.

D. Stay Open to Rethinking Your Future

27. Throw out the ten-year plan. What interested you last year might bore you this year—and what confused you yesterday might become exciting tomorrow. Passions are developed, not just discovered. Planning just one step ahead can keep you open to rethinking.

28. Rethink your actions, not just your surroundings. Chasing happiness can chase it away. Trading one set of circumstances for another isn’t always enough. Joy can wax and wane, but meaning is more likely to last. Building a sense of purpose often starts with taking actions to enhance your learning or your contribution to others.

29. Schedule a life checkup. It’s easy to get caught in an escalation of commitment to an unfulfilling path. Just as you schedule health checkups with your doctor, it’s worth having a life checkup on your calendar once or twice a year. It’s a way to assess how much you’re learning, how your beliefs and goals are evolving, and whether your next steps warrant some rethinking.

30. Make time to think again. When I looked at my calendar, I noticed that it was mostly full of doing. I set a goal of spending an hour a day thinking and learning. Now I’ve decided to go further: I’m scheduling a weekly time for rethinking and unlearning. I reach out to my challenge network and ask what ideas and opinions they think I should be reconsidering. Recently, my wife, Allison, told me that I need to rethink the way I pronounce the word mayonnaise.