Why We Make Mistakes (Book Summary)

What’s it about?

Why We Make Mistakes is about the kinds of mistakes we commonly make and the reasons behind them. With a broad focus encompassing neuroscience, psychology, and economics, the book provides convincing explanations for our often fallible perception, inability to recall simple data, and the many biases that direct our decision-making without us being aware.

About the author:

Joseph Hallinan is a journalist and writer who wrote for the Wall Street Journal and won a Pulitzer Prize for investigative reporting. Besides Why We Make Mistakes, Hallinan has also written the award-winning Going Up the River: Travels in Prison Nation and, most recently, Kidding Ourselves: The Hidden Powers of Self-Deception.

Humans are extremely egoistic, self-centered, critical, and biased beings that they become unaware of their restrictions and flaws:

These characteristics are obvious reasons why people make mistakes, regardless of the consequences and outcomes that may face them.

A great number of mistakes have spread through humanity due to the fact that people are unaware of the faults they make. The fact of you being unknowledgeable of your own mistakes will render you incapable of learning from them.

Through well-comprehended descriptions and many authentic examples, Hallinan was able to focus on the reasons behind people making mistakes, when and how they do them, and how to avoid their occurrence. If you are interested in the back story of the mistakes you and everyone make, this is definitely the book for you.

To be one step ahead in steering clear of making mistakes, you should know why people make them:

Anyone who tends to make a mistake will most likely blame it on the fact that we all are humans and it’s very common. Well, it is true. People are vulnerable and exposed to a lot of mistakes.

For the most part mistakes are the results of the universe achieving a certain pattern? Besides these patterns, expectations also contribute to these actions.

For example, if someone tells you that the wine you are drinking is from France it will seem better tasting to your mind without you realizing it even if it’s not actually from France. The problem with these automatic biases is that usually, people have no idea that they have them.

People also live for the drama; they like blaming and accusing and pointing fingers whenever something goes wrong and tend to misdirect the situation.

People often keep making the same mistakes. Because mistakes follow a certain pattern of repetition. Learning from your mistakes is dependent on your capability of knowing these patterns.

Our assumptions design the way we see the world and the way we act in it too:

An easy way to describe is when you see an argument between a couple: and you assume that the women are being assaulted when the man starts teasing her. Without thinking you go forward and punch him in the face, but maybe he happens to be retarded and you realize that you did a mistake. The truth is we don’t know the whole picture, and we can’t judge by what we see and expect.

Those judgmental assumptions we make are very common problems that scholars gave them a name: the “looked-but-didn’t-see” mistakes.

We can’t examine any case the way experts do, so we shouldn’t. We fail to see anything that refutes our subconsciousness.

Humans fail to remember random info like names in comparison to faces:

If you meet someone you knew 20 years ago you will most likely recognize his face but not his name. That’s because names, faces and all kinds of information related to your senses are stored in your brain in bits and pieces and it’s easier for your brain to recollect a picture since it is not random.

If you don’t want to lose a memory of something, make sure to attach it to some kind of emotional detail so that it will not be as random.

People give immediate conclusions about others based on irrelevant cues that affect their decisions in every way possible:

Well, the simplest way to describe it is by “don’t judge a book by its cover”, but people do that all the time even when they think they are giving natural and non-biased thoughts.

Let’s face it though, we are beings driven by emotions, desires, biases and a huge amount of social pressure. We prefer to make mistakes than stand doing nothing and account these mistakes responsible for not taking the required actions

Most people are not programmed the way they think they are:

People tend to polish their past actions and decisions to appear to their selves in a better, more favorable ways. To an extent that they recall their memories in events that didn’t even happen.

This behavioral issue makes people unaware of the mistakes they are doing and end up living in their own built fantasy.

A group of researchers once asked some students about their grades at school. More than 75% of them said higher grades that they actually got and chose unintentionally the answer they longed to.

You can only see what you look for; your sight can only spot what’s right in front of you. The image you’ll be seeing is what you already expect to see:

While pilots are heavily trained and equipped with everything a plane needs, plane crashes still happen regularly.

As captain Robert Loft was flying to Miami he lost focus due to the failure of an indicator light. All flight engineer, an aircraft mechanic, the officer, and captain Loft were so focused on fixing the indicator light that they forgot about flying the plane itself.

The plane crashed and 99 people were killed in the process.

People tend to keep going back and forth with no idea what were they doing before. They make mistakes in the process because they are just not able to multitask and find rational solutions to what they are facing under pressure.

People’s decisions are affected by 4 major ways: framing, timing, anchoring and skimming:

Researchers confirmed that if you are at a restaurant you order the wine corresponding to the music you hear. If you hear Italian music, you’ll order Italian wine. If you hear French music, you’ll order French wine and so on. This picture reveals the definite power of our surroundings on our decision. Four major factors affecting our decisions are:

Once an article of a great deal appeared on the front page of “The New York Times”. Investors duly responded and contacted the source to make a business deal. However, it appeared to be that another magazine published the same article a few months earlier on page A28 but no one responded. This explains how people are only influenced by what seems more important and authentic to be displayed on the front pages.

When asked what movie people wanted to watch the next week, most of them chose intellectual movies. While when asked what would they watch right now, they chose popular movies. This demonstrates that as long as the outcomes aren’t near, people are willing to take risks.

An example of anchoring is: a deal of 400$ purchase with 100$ shipping fee is not as attractive to customers compared to a 500$ purchase of the same object with free shipping. Both cases cost the same amount, but the fact that the prices have been anchored makes the real difference to people.

We tend to buy a box of pens for example without examining it if we are already familiar with these kinds of pens. Usually, people overlook the errors in a book because they concentrate mostly on the beginning of the words than complete the rest of the words in their heads.

If you ignore the fact that you’ve been biased, you’ll not be able to banish these biases and learn from your mistakes:

People make biased mistakes because they naturally incline towards things that seem nicer or neater. The type of person you are affects your image and information towards things

Gender and overconfidence play a big role in the reasons people make mistakes:

Usually, men are much more confident in their abilities than women. They tend to be overconfident in taking decisions.

In male represented fields, there are assumptions that the productivity and performance level will be high. Women, unlike men, do not take rash risks and decisions because they make mistakes more seriously than men do.

There are definite limits to the number of things people do at one instant. The more they do the more there is a chance of making mistakes:

Almost everyone is overconfident – except for people who are depressed, and they tend to be realists.”

-Stefano Della Vigna

Most people can’t see their limits, so they end up building ambitions and dreams that are beyond their abilities.

For you to see the real improvement you should:

  1. Think small. Uncomplicated measures can be much more effective than complicated ones.
  2. Calibrate. Calibration mistakes cause huge harm. That’s why recalibration regularly is a must for you to keep rating your steps.
  3. Thinking negatively. Although it is advised to stay optimistic, it is also essential to hope for the best and prepare for the worst. If you thought negatively, don’t let it overpower your mind. Find ways to be ready for the worst-case-scenarios.
  4. Let your partner proofread. It is impossible for you to cover everything with minimal damage on your own. Let your partner help you avoid some faults and accept criticism from someone you trust.
  5. Relax and rest. Get some sleep, you workaholic! Your body and mind function best when you are relaxed and well-rested. Most of your worst decisions are made under pressure and stress.
  6. Stay happy. It is proven that your productivity level is much higher when your body is secreting endorphins and dopamine. Thus reduce your chance of making mistakes.


The first step for correcting mistakes is knowing that you actually made one. Step down a bit from your self-centered mindset and think ahead before you make any serious decisions. Mistakes are part of our daily routine but a big part of them can be avoided.

Increase your happiness and stay in contact with what gives you joy. Trust that in persistence and healthy souls you can achieve anything.

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