clear thinking book summary

Book Summary: Clear Thinking by Shane Parrish

The Book in Three Sentences

In this book summary of Clear Thinking, Shane Parrish gives you the tools to recognize pivotal moments and use your cognitive abilities to get what you want. Unless we’re aware of our behavioral defaults, we’ll act emotionally rather than rationally and we’ll move further away from our goals rather than closer to them. Clear thinking has the potential to change your life.


This book provides a method for clear thinking and good judgment because no one teaches you how to think or make decisions. The author came to the conclusion that to obtain the results we want, we need two things. First, we must create a space to reason. Second, we must use that space deliberately. This is a skill we must cultivate, but once we do so, it gives us an unfair advantage.

Introduction: The Power of Clear Thinking in Ordinary Moments

Our future depends on ordinary moments. Generally speaking, ordinary moments matter more than big decisions. The problem is that while getting the big decisions right gives us a sense of direction, we still might not get the desired results. Ordinary moments seem insignificant, but they compound over time.

Part I: The Enemies of Clear Thinking

Chapter 1.1: Thinking Badly – Or Not Thinking at All?

There are certain moments when we need to think. If we don’t, we allow our impulses to take over. There’s often space between stimulus and response and this allows us to do one of two things: We can react rationally or we can react emotionally.

As a default, we’re biologically wired to react emotionally, but we mustn’t. We’re animals, and as such, we’re predisposed to defend our territory (our physical space, as well as our identity). Furthermore, we see the world around us as a hierarchy. In certain contexts, you expect everyone to be equal and when something happens and someone suggests they have a higher status than you, you react. We’re also self-preserving creatures. This means that when we don’t think, our desire to protect ourselves becomes our main motivator.

Reacting rationally demands time and energy. To preserve that time and energy, our brains, created stimulus-response shortcuts. These shortcuts encouraged our fitness, survival, and reproduction. But while those tendencies might have been useful at some point, they hold us back in the modern world.

There are four main instincts that represent our brain’s default:

  1. The Emotional Default: we respond to feelings rather than reason
  2. The Ego Default: we react to things that attack our self-worth
  3. The Social Default: we try to conform to the norms of the group
  4. The Intertia Default: we favor habits and comfort rather than change

Chapter 1.2: The Emotion Default

There are consequences to having an impulsive nature and this usually leads to mistakes. Feelings like anger or fear are natural, but acting immediately has consequences.

Chapter 1.3: The Ego Default

When driven by pride and ego, we can make poor decisions. The ego encourages us to protect our self-image no matter what and this can lead to unintended consequences. Our ego is a voice in the back of our mind telling us we’re better than we actually are. This can make us overconfident and arrogant. Sometimes, we have a shallow understanding of something and we feel confident, but this confidence blinds us. Instead of assuming we don’t know much about certain topics, the ego convinces us we know more than enough. The problem is that even when we hide our limited understanding of something, we’ll soon run into our own limitations.

Recognize the ego default when it appears. It usually appears when you spend energy on how others see you, thinking you’re an expert on a topic after reading an article or two, when you do your best to prove someone wrong, or when you can’t accept mistakes.

Chapter 1.4: The Social Default

When you gladly follow an idea because others do it as well, you succumb to what we know as social pressure. This happens because we want to belong and we fear being an outsider. Thousands of years ago, surviving outside our tribe was impossible, so we’re wired to conform with a group. This is why we adjust our behavior when we’re with other people. Put simply, we have a natural instinct to fit in.

The social default makes us afraid of being ridiculed. The problem is that fear prevents us from reaching our full potential. To succeed, you might have to be willing to be called a failure by your peers. By doing what everyone is doing, you’ll achieve the same results. Thinking clearly demands thinking independently. This will make you incredibly uncomfortable, but it’s the only way to get extraordinary results.

The problem is that deviating from the status quo alone won’t lead to success. You have to be willing to be different, but you also need to be right. Nobody who tries to conform will make an impact. Real change happens when you think independently and when there’s a chance you’ll be ridiculed.

The social default appears when you try to fit in, when you don’t want to disappoint others, or when you don’t want to be an outsider.

Chapter 1.5: The Inertia Default

Inertia is a Latin word that means laziness or idleness. In physics, inertia explains how objects resist change when left alone. In a way, these definitions also explain why it’s so hard to change our minds: We’re likely to continue the same behavior unless an external force changes our direction somehow.

We resist change because not doing anything is easier than doing something. Also, making changes can lead to undesirable results, so we rather be mediocre than try to achieve greatness and look like idiots in the process. While the “zone of average” gives us comfort, it also means we’ll never get the chance to improve. We must cultivate the ability to adapt.

The inertia default appears when you avoid conflict or when you resist change because continuing on the same path is easier.

Chapter 1.6: Default to Clarity

Learning to manage our defaults improves our behaviors, helps us achieve our goals, and adds meaning to our lives. Getting rid of our defaults is impossible, but we can reprogram them. To change our defaults we don’t have to rely on our willpower, but on changing our environment.

Part 2: Building Strength

Since our defaults are part of our biological tendencies (self-preservation, maintaining social hierarchies, and defending our territories), we can’t simply remove them. That said, we can use them to our advantage. For that to happen, we first have to build strength, something that turns inertia into an unstoppable force. Positive inertia requires rituals because they force the mind to focus on what’s coming next, not what happened last. The more you do this, the more you cultivate a sense of good judgment.

We need four strengths:

  • Self-Accountability: learning new abilities and using reason for your actions
  • Self-knowledge: identifying your strengths and weaknesses
  • Self-control: managing your fears, desires, and emotions
  • Self-Confidence: believing in your abilities

Chapter 2.1: Self-Accountability

Self-accountability refers to taking responsibility for yourself. Without self-accountability, you can’t move forward because you’ll run on autopilot and you’ll pursue external rewards. Also, people who aren’t self-accountable don’t take responsibility for their mistakes. We must understand that regardless of what happens, there’s always something we do today to improve our tomorrow. You don’t need anyone to hold you accountable because you can do this yourself.

Blaming others or our circumstances is a way to protect our ego. This is called self-serving bias, a habit where we evaluate a situation to defend or improve our self-image. Not everything is your fault, but it is your responsibility. When something outside of your control happens, it isn’t your fault. How you deal with it though, is your responsibility.

When this is the case, we have a choice, we can put our time and energy into the things we control or the things we don’t. When you take responsibility for your actions, you’re choosing to be exceptional. This is accepting a challenge and doing your best instead of complaining. Trying to prove you’re right is a waste of time and energy because you care more about your ego than the outcome. Sometimes we have to accept that things outside of our control just happen, even if they seem unfair. Don’t focus on what you can’t control (the situation), focus on what you can control (your response).

While complaining is easy, it’s never the solution. Facing reality is the solution. Being in a position where you always blame someone or something else makes you a victim.

Chapter 2.2: Self-Knowledge

Self-knowledge involves knowing your strengths and weaknesses. To succeed in life, you must have an understanding of what you know, as well as what you don’t know. In a competitive environment, facing people who know more things than you means you’ll lose. Figuring out your unfair advantages and sticking to them is your best bet. Additionally, you must know when you leave your area of expertise.

Chapter 2.3: Self-Control

Self-control is about mastering your fears, desires, and emotions. As humans, we can’t escape from our emotions because we’re wired to respond to external threats. Although we can’t get rid of our physical reactions or the conditions that cause them, we can control our reactions. To reach most goals, you need discipline, not emotional intensity.

Chapter 2.4: Self-Confidence

Self-confidence is believing in your abilities. To think independently, self-confidence is essential. To acquire self-confidence, you need to learn new skills and abilities. While self-confidence is a strength, confidence without humility is a weakness. Confident people can admit vulnerabilities without giving in to despair. They can also accept reality even if it’s hard which means they don’t waste time denying something that happened.

One of the rarest qualities in people is their ability to change their minds. To be right, you must accept that you’re wrong sometimes. Admitting you’re wrong isn’t a liability, it’s an asset. It means you’re strong, adaptable, and courageous. To be self-confident, focus on what’s right, not on who’s right.

Chapter 2.5: Strength in Action

When self-accountability, self-knowledge, self-control, and self-confidence work together, you exercise good judgment.

Chapter 2.6: Setting the Standards

To build strength, raise the standards. One way to do this is by looking at your environment and avoiding the wrong people. We’re more likely to adopt the qualities of those around us, so don’t hang around with people who are jerks, selfish, and unkind. All top performers have high standards.

Chapter 2.7: Exemplars + Practice

To build strength by raising the standards, you need two things:

  1. Choose the right exemplar: this is someone who excels in a specific area, skill, trait, or value
  2. Imitate them: think about what they’d do under certain circumstances and do that

Find people with the attributes you want. For this purpose, some people have a “personal board of directors”, a group of people who have the skills or attitudes you want. You can change this list as time goes on. You can even choose real or fictional people and to become members of your board, the only thing you need is to gather information about them. Remember that you don’t have to compete with them, you just want to feel inspired so that you become a better version of yourself.

Part 3: Managing Weakness

To take command of your life, focus on the things you can control and manage the things you can’t. We refer to the latter as your weaknesses.

Chapter 3.1: Knowing Your Weaknesses

Some of our weaknesses are physiological (hunger, thirst, fatigue, sleep deprivation, distractions, or stress) and they can make us react without thinking clearly. Some of our weaknesses aren’t biological but acquired through habits though. Bad habits seem inconsequential because there aren’t immediate consequences after doing them. Eating ice cream once, for example, won’t ruin your health. But the more you engage in bad habits, the more chances you have of ruining your life. For instance, if you miss meals with your family enough times, your relationship with them will degrade.

You can manage your weaknesses in two ways. First, build your strengths. Two, implement what the author calls safeguards. Some weaknesses are blindspots. This is our inability to think and judge things properly. Our job is to identify blindspots and manage them. There are three main reasons why we fail to see our weaknesses. One, those flaws are so ingrained in us that we don’t even notice them. Two, seeing certain flaws hurts our ego. Three, our perspective is too limited.

Chapter 3.2: Protecting Yourself with Safeguards

Some biological vulnerabilities negatively impact our judgment. While we can’t avoid them, we have our own safeguards to diminish their impact. Safeguards are tools we use to protect ourselves from certain weaknesses. For example, if you want to start a healthy diet, getting rid of all junk food is a safeguard.

Safeguard Strategy 1: Prevention: this is about preventing problems before they happen. For example, you avoid making decisions when you’re hungry, angry, lonely, or tired.

Safeguard Strategy 2: Automatic Rule for Success: sometimes we make decisions based on the outcome we want to achieve. To reach a certain goal, we rely on willpower. The problem is that once we achieve a goal, it’s easy to go back to a default behavior and move further away from the goal we just reached. To pursue goals, we need to be consistent. These choices add up and you get closer and closer to your goals. A way to bypass choice is to create automatic rules. For example, you only drink socially when you feel like it or you exercise as soon as you wake up even when you travel. The advantage of making up rules is that you don’t have to make choices on a case-by-case basis. Another advantage is that people won’t argue with your personal rules. They’ll question your decisions, not your rules.

Safeguard Strategy 3: Creating Friction: when you encounter things that are opposite to your goals, you increase the effort it takes to do them. For example, you disconnect and put away your video game consoles, so every time you want to play a game, you have to set everything up again.

Safeguard Strategy 4: Putting In Guardrails: this strategy involves creating distance between a situation and your reaction to it. When you step back from a situation and think about your goals and the best way to reach them, you’ll make better decisions. For this purpose, you can use checklists or prompts.

Safeguard Strategy 5: Shifting Your Perspective: we look at things from a specific point of view, but luckily for us, we can shift our perspective. Having an outside perspective of a situation gives you more details of what’s actually taking place.

Chapter 3.3: How to Handle Mistakes

Everyone makes mistakes. This is the case because even if you have knowledge, there are other factors that affect your success. The problem isn’t to make mistakes, the problem is how you deal with them when you do.

When something bad happens, we blame external forces. This is called self-serving bias, a tendency to judge things in a way that protects our image. When something good happens, on the other hand, we attribute that success to our great qualities. This is a reductive way to see the world around us though. When something bad happens, it happens because of one of two things: luck or you were wrong. In the first case, we should take a different approach next time. In the second case, you need to update your thinking. The latter is extremely difficult because it requires you to accept the fact that you’re not as smart or knowledgeable as you thought. In other words, this bruises your ego. Also, changing our ideas about the world takes time and effort.

When we make a mistake, we have a choice. We either update our ideas or we ignore what happened. The mistake isn’t usually that bad, but avoiding taking responsibility for it is more expensive than you think.

Covering up our mistakes causes three problems:

  1. You can’t learn unless you accept what happened
  2. Hiding mistakes becomes a habit
  3. Covering turns a bad situation into something worse

By admitting your error, you choose a better path, one that saves you time and prevents you from repeating the same mistake again.

To handle mistakes effectively:

  1. Accept responsibility
  2. Learn from the mistake
  3. Commit to doing better
  4. Repair the damage

Part 4: Decisions: Clear Thinking in Action

Decision-making is a skill. The author explains the difference between a choice and a decision. A choice is selecting an option from a series of alternatives. A decision, on the other hand, involves conscious thought.

To make the best decision possible, you must go through four stages: you define the problem, you explore tentative solutions, you evaluate said options, and you choose the best one. In most cases, there are consequences to making poor decisions, so reacting quickly isn’t the best course of action. When the stakes are high, the potential losses can be big, so the best thing you can do is to take your time and make a careful decision.

Chapter 4.1: Define the problem

The first principle of decision-making is to define the problem. This has two components. First, the desired outcome. Second, the obstacles that prevent you from getting there. You can’t solve a problem unless you’ve defined it correctly. This is an example of reacting without reasoning. By defining a problem, the solution will seem obvious.

The author introduces two principles:

  • The definition principle: this involves defining the problem and you can’t outsource this part of the process.
  • The root cause problem: this involves identifying the main cause of the problem instead of its symptoms.

To safeguard the problem-defining stage, Parrish suggests the following:

  • Build a problem-solution firewall: separate the problem-defining phase by having two different meetings, one to define the problem and one to solve it. The idea is that once you understand the problem well, you’ll know what to do.
  • Use the test of time: will your solution stand the test of time? If the answer is yes, that means you’re addressing the problem and solving it permanently. If the answer is no, that means you’re addressing the symptom, so the problem will persist.

Chapter 4.2: Explore Possible Solutions

Now that you understand the problem, you must come up with solutions. The best way to do this is by imagining possible scenarios. The worst way to deal with our problems is to avoid them or treat them as if they will disappear. To get the future we want, we need to make choices that will get us there. For this purpose, we can use a premortem, this is a psychological experiment that prepares us for potential problems. It’s easier to deal with problems when we expect them.

Imagining potential setbacks makes you prepared. Parrish suggests the bad outcome principle which involves imagining everything that could go wrong and ways in which you can deal with them. Nobody is immune to bad things, so become a great decision-maker by making contingency plans.

To consider your options, use the second-level thinking principle which encourages you to ask “And then what?”. Second-level thinking involves considering all the possible ramifications of your decisions. Some choices seem insignificant when you make them (such as eating junk food for dinner), but they compound over time.

First-level thinking is looking at the problem without the future repercussions a solution might lead to. Second-level thinking is looking at the problem now, as well as the consequences a solution might have. In other words, second-level thinking is about considering the outcomes of those outcomes.

There are two safeguards against binary thinking.

  • Imagine that one option is off the table: this forces you to see the problem in a different way.
  • Come up with both-and options: this involves combining both possible options

To think better, we need to see past the obvious to find what’s hidden. By definition, choosing something means ignoring all the other alternatives. We’re inclined to see what we gain by choosing something, but we should forget about what we lose by declining another.

There are two principles related to opportunity costs:

  • The opportunity-cost principle: this is considering the opportunities you’re declining when you choose an option.
  • The 3-lens principle: opportunity costs can be viewed through three lenses. First, compared with what? Two, and then what? Three, at the expense of what?

Chapter 4.3: Evaluate the Options

Now that you’ve evaluated the options, you need to pick one. There are two parts to consider here. First, your criteria for evaluating options. Second, how to apply said criteria. Examples of criteria include opportunity cost, return on investment, and likelihood of the desired outcome. Each problem has its own criteria.

Criteria have the following features:

  • Clarity: the criteria must be simple
  • Goal promotion: the criteria must support the options that attain the desired goal
  • Decisiveness: the criteria must favor one option

You must be clear on what’s important to evaluate your options more easily. To apply said criteria to your options, they have to meet two conditions: they must be relevant and they must be accurate. To get information that’s relevant, you need to consider the targeting principle. This involves knowing what you want before you look at the data. To get information that’s accurate, you need to consider two principles. The HiFi principle is all about finding high-quality information. This means that’s unbiased and close to the source. To make the best decision, you need access to the best information.

Here are some safeguards to guarantee you’re always getting high-quality information.

  • Run an experiment: this is about trying something to see what happens. You can, for example, sell a product before you have created it.
  • Evaluate people’s motivations: sometimes you must rely on someone else’s information and it’s your responsibility to evaluate their perspective on the situation. Often, someone’s view of an issue is different than reality and it’s your job to consider all perspectives.
  • Ask people detailed questions: this involves asking how they think, not what they think.

The other important principle to get accurate information is the high-expertise principle or HiEx principle which comes from those who have a lot of knowledge and experience.

Here are some tips to approach an expert:

  • Show them you’ve spent time, energy, and money on the problem
  • Be clear on what you expect from them
  • Be respectful of their time and energy
  • Ask experts how they think and then listen
  • Follow up on your progress

There are many people who claim to be experts, but they’re imitators. To tell the two apart, the author suggests a few safeguards:

  • Take the time to distinguish the two: experts are usually enthusiastic about certain areas. Also, they spend their free time mastering their skills. Imitators can’t answer deep questions, they can’t adapt their vocabulary, they get frustrated when you don’t understand, they’re open about the ways in which they’ve failed, and imitators don’t know their limits.

Chapter 4.4: Do It!

Once you’ve considered the options, evaluated them, and found the best, you must act. We often fail to act because we’re scared of the consequences. Also, we’re scared about being wrong. This can make us get stuck because we keep telling ourselves we need more information before making a decision.

To determine when’s the time to stop thinking and start acting, you should consider these three principles. Before doing that, you need to classify decisions by considering how consequential and how reversible they are. Consequential decisions impact the most important things. For example, who you marry or where you live. Reversal decisions can be undone. For example, signing up to Netflix.

  • Some decisions are highly consequential and irreversible and the cost of making a mistake is high. The opposite is a decision that’s inconsequential and easily reversed where the cost of a mistake is low.
  • The ASAP principle: when the cost to reverse a decision is low, make it fast. When you’re dealing with inconsequential things, make a choice and move on. This saves time, energy, and decisions.
  • The ALAP Principle: if the cost to reverse a decision is high, delay it as much as you can. When the stakes are high, you want to make decisions at the last possible moment because this helps you gather more information and consider all possibilities. When failing is cheap, make the decision as fast as possible, when failing is expensive, learn as much as you can before doing anything.
  • The stop, flow, know principle: don’t gather more information when one of the following things happens. One, you stop gathering useful information. Two, you first lose an opportunity. Three, you know something that makes an option obvious.

Chapter 4.5 Margin of Safety

One way to move forward during the decision-making process is to eliminate the options that might lead to the worst outcomes. A margin of safety is a space between what you expect to happen and what might happen. This is like buying insurance, it seems unnecessary, but when you actually need it, it seems incredibly valuable.

There are many unknown factors about the future: health issues, relationship problems, financial pressures, a war, a pandemic, and economic collapse, and so on. Every scenario could have its own margin of safety. As a general rule, a successful margin of safety should be able to handle twice the amount of issues that would lead to a crisis. Also, never overinvest in a potential option because if it fails, it can ruin you.

Don’t announce a decision as soon as you make it even if you want to. It’ll be harder to change your mind once you do. It’s important to have execution fail-safes so that your decision goes as planned. Execution fail-safes are a way to think when you’re at your best so that you avoid mistakes when you’re at your worst. For example, Ulysses told his crew to tie him to the mast of the ship so that he could listen to the alluring song of the sirens. Fail-safes are indispensable.

Parrish lists three kinds of execution fail-safes:

  • Setting up trip wires: this is detailing a plan so that you know what to do when certain conditions happen. Negative signs tell you that something is wrong, so ignoring them for too long can have serious consequences.
  • Empowering others to make decisions: when you lead a team, you should encourage others to make decisions. This ensures that if something happens to you, your organization can still function well. There are four components to a commander’s intent (this is giving your team the rules to carry out the mission): Formulate, communicate, interpret, and implement.
  • Tying your hands: these are limits you impose on yourself so that you never feel tempted to go off course. For example, when you decide to eat healthily, you get rid of all of the junk food.

Chapter 4.6: Learn from Your Decisions

Making great decisions on a consistent basis gives you an advantage and so is learning from our decisions.

To evaluate your decisions, we can use different principles:

  • The process principle: when looking at a decision, focus on the decision and not the outcome. All decisions might seem bad in retrospect if the outcome was undesirable, but this isn’t the case. Sometimes the decision was the right one, even if the outcome wasn’t the intended one. When this happens, learn from what happened instead of ruminating about the past. There are two things that come into play here and they’re independent of each other: the quality of the decision and the quality of the outcome. When you see both things as equivalent, we’re resulting. We see the result as an indicator of the quality of the decision which isn’t fair.
  • The transparency principle: your decision-making process should be visible. Think about the steps involved in the process, and reflect on them before moving forward. For this purpose, you can use another safeguard. The safeguard in question is to write your thoughts when you make the decision. this may come in handy in the future so that you learn from your mistakes. Writing ideas makes the invisible visible. Also, you may realize that you didn’t understand things as well as you thought. You can show your reasoning to others and they can check the process for errors. Finally, writing things down can help you teach your decision-making system to other people.

Part 5: Wanting What Matters

Good-decision making has two parts:

  1. Knowing how to get what you want: this involves making effective decisions that bring immediate results (such as closing a sale).
  2. Knowing what’s worth wanting: this involves making good decisions that bring long-term goals (such as finding the right person to marry).

Chapter 5.1: Dicken’s Hidden Lesson

Ebenezer Scrooge is one of Dickens’ most beloved characters. When he’s visited by three spirits, he can see the consequences of all the decisions he’s made throughout his life. When you pursue external things (money, fame, power, and so on) you’ll realize you’re living someone else’s ideals instead of your own. Pursuing external things won’t make us happy because we’ll always want more. In psychology, this is called the hedonic treadmill. When you’re on the hedonic treadmill, you’re happy when you get something (a large sum of money, an expensive car, or a promotion), but happiness isn’t supposed to be conditional. The things that matter the most in life aren’t external but internal.

Chapter 5.2: The Happiness Experts

In general, older people are happier than younger people because they understand the value of time. Happiness is a choice, not a condition.

Chapter 5.3: Memento Mori

What do you think will matter more as you contemplate the final moments of your life? The practice of thinking about the end of our lives is important because it gives us a map. There’s always time to correct the course, but remember the things we regret the most are often the ones we don’t do, not the ones we do. The pain of trying and failing is easy to recover from. The pain of never having tried can be unbearable.

Likewise, when people are on their deathbeds, they don’t think about the possessions they’ve accumulated. Instead, they think about their relationships and the memories you share with them. We live for everyday moments, not big prizes.

Chapter 5.4: Life Lessons in Death

Using death as a tool to evaluate your life is scary but also powerful. Death helps us determine what matters most. It gives us clarity and perspective. Death makes a path before us so that we can walk toward the future we want.

Conclusion: The Value of Clear Thinking

Clear thinking takes time and effort but it’s worth it. To exercise good judgment we need a basic level of awareness to understand we’re making a decision in the first place. To improve your judgment, you need to implement a series of safeguards so that the path ahead becomes easier to navigate. Your behavioral defaults may conspire against you, but you can override them so that you can still move in the right direction. You can’t teach good judgment, but luckily, you can learn it.

Further Reading

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