The Elephant in the Brain by Kevin Simler and Robin Hanson: Summary & Notes

Front cover of The Elephant in the Brain by Kevin Simler and Robin Hanson.

In short

The Elephant in the Brain looks at the hidden reasons and motivations of many of the things we do. To paraphrase J.P. Morgan, everyone has a good reason to do something and a real reason. The “real reasons” of why we do what we do – that are often hidden from our consciousness – is what Simler and Hanson explore in this book.

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Book Summary & Notes

All text between quotation marks is taken directly from the book.

“Every man alone is sincere. At the entrance of a second person, hypocrisy begins.” – Ralph Waldo Emerson

The Elephant in the Brain is on the hidden motives of many of our actions. We’re not just capable to have these hidden motives, but we’re designed to have and use them out of self-interest. However, we don’t want to appear selfish to other people – this is why our brain hides these hidden motives from our consciousness. Our self-deception is a strategic choice.

Hidden motives are not just something we do in private, as a species we also do them in public, together. When this goes on for a long period, we end up with institutions (like schools, or hospitals) that are built with these hidden motives in mind (at least partially).

“[O]ur institutions harbor giant, silent furnaces of intra-group competitive signaling, where trillions of dollars of wealth, resources, and human effort are being shoveled in and burned to ash each year, largely for the purpose of showing off. Now, our institutions do end up achieving many of their official, stated goals, but they’re often rather inefficient because they’re simultaneously serving purposes no one is eager to acknowledge.”

The authors argue that the book is good for developing situational awareness: we only really can understand human behaviour by looking at how people behave, not what they tell themselves or us.

Animal behavior & Competition

“Knowledge suppression is useful only when two conditions are met: (1) when others have partial visibility into your mind; and (2) when they’re judging you, and melting out rewards or punishments, based on what they “see” in your mind.”

Most people would probably prefer that our intelligence evolved due to cooperation – the smarter we are, the better we can cooperate. But, in reality, it’s more likely that human intelligence is due to social challenges, zero-sum games, and competition.

In a competitive environment, we need to show our own desirable traits. This helps to raise our value and makes it easier to get higher status jobs, friends, and partners. It’s also the reason why we are constantly judging others and judging ourselves.

Judgments are “mediated by signals”, which is a piece of information that tells us something. Such as signs of health, aggression, strength, et cetera. Signals can be honest – when they actually are linked to a trait of the organism – and they can be deceptive, meaning: getting the benefits without having the costs. “That’s why the best signals – the most honest ones – are expensive. More precisely, they are differentially expensive: costly to produce, but even more costly to fake.”

Norms & Cheating

Why would people risk standing up to norm violators? It’s dangerous and risky to an individual. But by adding a reputational element it makes sense to take those risks. People who help to stop norm violators and cheater show leadership and initiative, and so norm enforcement becomes viable.

“We typically treat discretion or secret-keeping as an activity that has only one important dimension: how widely a piece of information is known. But actually there are two dimensions to keeping a secret: how widely it’s known and how openly or commonly it’s known. And a secret can be widely known without being openly known – the closeted lesbian’s sexuality, for example, or the fact that the emperor is naked.”

So cheating is about discretion: you need to keep others from knowing. Sometimes a single dimension is of importance, e.g. cheating on an exam – should not be widely known, or e.g. drinking in public – most people might know what you’re doing, but it should not be openly known.

For the cheater, it’s important to improve the odds of not being prosecuted, which is why discretion is used. Discretion can have multiple forms, such as having a pretext (alibi’s or excuses), communicating discretely (speaking in low voices, cryptically, in symbols, et cetera), skirting instead of violating a norm (grey areas), or being subtle (if something is not on the record, it will often get a pass).


“We don’t just deceive others; we also deceive ourselves. Our minds habitually distort or ignore critical information in ways that seem, on the face of it, counterproductive. Our mental processes act in bad faith, perverting or degrading our picture of the world.”

Because our expressions and minds aren’t as private as we think, it makes sense that we use self-deception to mislead others. We’re not lying, because in our conscious minds we think it’s true.

In a way, our conscious minds operate as a ‘press secretary’. Just as with public relations in a firm, where they are used for strategic ignorance, our brain’s press secretary avoids the elephant in the brain and will not admit that we do things for personal gain or other selfish motives.

Body Language

Body language is not arbitrary – it’s not just a way of communication, but also functional (for example when moving aggressively before a fight). It’s a way of honest signalling and difficult (“expensive”) to fake.

Depending on the type of situation, eye contact can mean different things. In a context of dominance, eye contact is linked with aggression – so the dominant person looks at what he/she wants, and submissive people look away. In areas of prestige, eye contact “is a gift”, high-status persons receive more attention from lower-status people.

Visual dominance ratio: the ratio of eye contact while speaking vs. eye contact while listening. If the ratio is equal then this is a sign of dominance, but if you make less eye contact when speaking your dominance status will be lower.

“This is the magic of nonverbal communication. It allows us to pursue illicit agendas, even ones that require coordinating with other people, while minimizing the risk of being attacked, accused, gossiped about, and censured for norm violations. This is one of the reasons we’re strategically unaware of our own body language, and it helps to explain why we’re reluctant to teach it to our children.”


Laughter can be used to explore norm-related dangers. A child, for example, enjoys potty humour because while the norm might be clear, the boundaries need to be explored – how serious is this? If people laugh when she does something it’s clear that while it might violate a norm, it’s not serious enough.

“A real danger of laughter […] is that we don’t all share the same norms to the same degree.”

If we laugh about other people, two things are important: 1) how much actual pain there is for the person, and 2) the psychological distance – the further away, the more difficult it is to empathize and the easier it is to laugh at them.

“Laughter, then, shows us the boundaries that language is too shy to make explicit. In this way, humor can be extremely useful for exploring the boundaries of the social world. The sparks of laughter illuminate what is otherwise murky and hard to pin down with precision: the threshold between safety and danger, between what’s appropriate and what’s transgressive, between who does and doesn’t deserve our empathy.”


Conversation is not just an exchange of information but it has other benefits as well. Speakings is also about showing off (to potential mates or allies) – while speaking costs effort and energy, benefits are gained in terms of social status.

Every time we speak there are two messages: the text and subtext. The first is a piece of information, what is actually said. The second shows that the speaker knows things, is well-informed, and is valuable to have around.

In academia and research people consume studies clustered around a certain topic, and so those clusters tend to grow over time. The authors state that the more popular a certain topic is, the less reliable it tends to be. There’s often greater value outside fashionable topics but this is neglected by other academics and researchers.


Keynes prediction that we would be working fewer hours as economic prosperity went up didn’t materialize. Part of the reason is that we’re in a rat race, or to put it differently: “a game of competitive signaling.” It doesn’t matter how prosperous we are, we are still fighting for sex and social status.

Third-person effect: people often say they are not influenced by marketing and advertising themselves, but they believe other people will be influenced by it. This helps to explain why, even if you don’t believe in something yourself, you’re still likely to buy a product based on what you believe are other people’s perceptions.

This is also why the reach of an ad matters: because people care how many others have seen the ad – “you need to see the ad and be confident that others have seen it too.”


Art can be valuable either through intrinsic properties (colours, textures, brush strokes, et cetera) or extrinsic properties (the artist, techniques, originality, et cetera). If for example the art is intrinsically beautiful, but not extrinsically (for example a picture or reproduction of a painting), the perceived value is low.

If something becomes easier to produce, then it becomes less valuable. One explanation of why paintings moved from realistic to abstract is the introduction of photography. With new technologies, it became easy to make realistic pictures, so painters had to invent new “valuable” genres/aesthetics.


Why do we give to charity? It depends on five factors: the visibility (the more visible, the higher the amount), peer pressure (are we socially influenced), proximity (local is better than global), relatability (if we can identify with the story/facts), and mating motive (men, for example, tend to give more if they are asked by an attractive female).

Spontaneous generosity is a more attractive quality than planned generosity – it shows that giving is part of our character. “[It] may not be the most effective way to improve human welfare on a global scale, but it’s effective where our ancestors needed it to be: at finding mates and building a strong network of allies.”

Methuselah trusts = putting charitable money in a trust and letting it grow for 50-100 years before spending it. Benjamin Franklin set one up. But from a signalling point of view, they hold little value since we’re not rewarded here and now but long after we’re dead.


Education might be valuable on an individual level, with averages increases in income of 8-12%, but on a national level education only raises income from 1-3%. If schooling were a 100% effective this difference shouldn’t exist.

So what is then the value of education? Mostly signalling & credentialism. It shows future employers that the employee has work potential.

Due to these hidden motives, what is seen as a flaw is actually a feature. It’s not what students learn, it’s the ability to learn. The boring busywork most courses consist of is about separating the wheat from the chaff, and so it’s not meant to be fun. This then also explains the difference between income levels after education from an individual and society as a whole: the more education is about signalling and credentialism the less a nation stands to gain.

The workplace is an unnatural environment for humans – doing repetitive tasks, keep constant focus, force yourself to adopt someone else’s time schedule, et cetera. This is why schooling acts as domestication – it helps humans get used to these strange and unnatural environments. Education is domestication.

This domestication does not stimulate learning. In fact, it actively reduces learning and curiosity. As Albert Einstein said: “It is… nothing short of a miracle that modern methods of instruction have not yet entirely strangled the holy curiosity of inquiry.”


People have always been interested in medical care, even when that care was useful dangerous or harmful. The science might have been lacking, but the care and attention from a medical specialist were always sought out.

Excess medical care is a real issue. Studies show that the longer people are kept in hospitals, the shorter their life will be. One study found that for every extra day in the ICU people lived 40 fewer days in total. Spending $1,000 on a patient had a range of -20 to +5 days of life. These are correlational, but a major randomized RAND study found that there were no health differences depending on the amount of medical consumption.


Religion isn’t really about internal beliefs, but about beliefs shared in a community. “A religion, therefore, isn’t just a set of propositional beliefs about God and the afterlife; it’s an entire social system.”

Religion helps to facilitate trust between people. Today we can maybe use contracts or credit scores, but in the past church attendance was a good heuristic for determining if people were trustworthy or not.

But why would others care if we believe in a supernatural God? Well, if people believe in God they will probably behave well because they fear punishments, and so you want to convince other people that you believe in God and one of the best ways to display that to others is to actually believe it. “The more fervently we profess belief in such a god, the more we’ll develop a reputation for doing right at all times, even when other people aren’t watching.”

How strange religious practices are can be a barometer for the strength of the religious community. The weirder the beliefs or practices, the stronger it is. The costs of upholding this are high, and that is exactly the point since it takes real investment to join the community and be socialized into it.


Voting is also a form of loyalty signalling – this explains people tend to vote for group interests rather than individual interests.


How to use this knowledge of the elephant in our brains?

  • First, through better situational awareness – understanding the human social environment to a deeper extent.
  • Second, to understand our own (hidden) motives better. “After all, many of our perceptions are colored by self-interest, including our perceptions of what other people are up to.”
  • Third, acknowledging hidden human motives to others and talking openly about them, might be appreciated in some communities.
  • Fourth, choosing to behave better. Meaning: to stop acting on our hidden motives, or to put ourselves in situations where our ideal and hidden motives are aligned.
  • Fifth, by adopting a philosophy of ‘enlightened self-interest’, that is: doing well ourselves by doing good for others (as with, for example, Benjamin Franklin).
  • Finally, by influencing policy or designing institutions. Hidden motives are usually not taken into account there, resulting in disappointing results because what people say they do or want, is usually not what they actually do or want.

Interested in The Elephant in the Brain? Get the book on Amazon.

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