Homo Deus by Yuval Noah Harari [Book Summary]


The beginning of humans and humanity’s consequent control over the earth started with Homo sapiens’ creative skill, consciousness, and idea. Religion and humanist philosophy have tried their best to bring this power into being, putting humans at the heart of creation and idea.

Certainly, with the fast development of science and technology, computers and artificial intelligence, it looks like little can stop us. However, can we be digging our own failure?

This book talks about the emergence rise of humans and the principle of human superiority. You’ll get to know what allowed us to control this planet and the reason we believe that we are special. However, you’ll also look ahead and notice what threatens our crown – and could start the fall of human beings.


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Chapter 1 – What heights we succeed! Humanity’s goals change daily. 


Development and innovation are nothing new for humans. We have made every effort for the stars and gotten to the moon. We have created the approach to conquer famine, disease and the effects of war. However, as we progress, our goals have to be changed.

Let’s look at how far we have progressed.

Now we can see the spread of famine and disease – disasters that killed a lot of people in the olden days.

For instance; between the years 1692 and 1694 in France, famine caused the death of 15% of the population (that’s nearly  2.5 million people). The notorious Black Death pandemic caused the death of about 75 and 200 million in Eurasia during the 1330s. That’s nearly a quarter of its total population.



However, presently, we have almost defeat famine and disease. As a matter of, you’re more likely to die from obesity than hunger. Three million died globally as a result of obesity in the year 2010. On the other hand, malnutrition and famine together killed just a third of that amount.

We’re really advanced that we assess our disasters on a different scale. Consider the issue of Ebola. Though it’s seen as an extreme modern epidemic, it caused the death of “only” 11,000 people.

It’s very similar to war. It’s an exceptional event instead of a given. We are very likely to die from diabetes (1.5 million deaths in 2012) than war (120,000 in 2012).

Is this relevant? Well, it signifies that as a species humankind can change its aims. We can target to live more or become gladder and stronger.

We’re on the path. Twentieth-century medicine has nearly increased our life span by two-fold. Some people even believe that we can become immortal. Also, we feel like we can live more happily. This is the reason why, according to a 2013 Survey conducted on Drug Use and Health, more than 17 million Americans reported making use ecstasy.

Also, technology is utilized to fortify our bodies. Nowadays paralyzed patients control bionic limbs with thought only.

However, it’s only the beginning. We can strive greater yet.


Chapter 2 – Humans claimed dominance over animals and demonstrated it through joint cooperation.


Humans are definitely the universe’s most successful creatures. However, are we going to be able to maintain this?

If we wish to identify where we’re going to, we need to have an idea of where we originated. What made us really strong?

Since we stopped to be hunter-gatherers, we’ve claimed dominance over other animals. We began domesticating livestock at nearly the exact time we changed to agriculture, nearly 12,000 years ago.

At the moment, over 90% of big animals are domesticated. The disadvantage is that domestication causes animal suffering. For example, sows are isolated to gestation crates, hardly able to go around, and are slaughtered when their bodies can’t handle it again. Remarkably, the majority of the people are okay with this: it meets our want for inexpensive, abundant meat.

However, what makes us really special that we believe we can hurt animals like this?



Consider it this way: we aren’t metaphysically really different from other animals.

We tend to believe that we are in some way different since we conceive of “the human soul.” Monotheists assert that we’re exceptional in owning this soul. However, there’s no proof that that kind of thing is in existence, or that we can separate ourselves from animals through its existence.

Perhaps you believe that animals possess a “lesser” consciousness? We are still not aware if human consciousness is really different from animal consciousness. Nevertheless, contemporary science still can’t clarify what consciousness truly is!

Maybe our world supremacy can be looked at in another way. Let’s think about our skills to work together flexibly on a huge scale. For example, during the last US election, almost 40 million people succeeded to go and vote on a fixed day, followed the same rules and approved to respect the outcomes.


Chapter 3 – Religion has offered us stories and these summarize moral problems.


Cooperation offered us a competitive advantage. However, what allowed us to cooperate together in the first instance?

This cooperative want is shown in shared stories. When we share a narrative; we share values as well. 

Think that during the late twelfth century, European leaders came together in the Third Crusade. Their aim? To regain Jerusalem. People across Europe joined forces to fight as allies. This even comprised the French and the English, who finished their own war to do that! What allowed this to be possible? That is, they had the same Catholic religious faith story. Also, so, they believed they’d get eternal salvation for their labors.

Religious stories are similarly powerful nowadays; however, they have transformed into some surprising forms.

Nobody is going to cooperate with you on a mission to defeat another country because the Pope said you should do it. You’d be mocked. However, it isn’t because there is no religion again. It only seems different.

Let’s go back to basics. What is religion? For beginners, let’s mention what it isn’t: superstition. It’s not about faith in supernatural beings. Religion is the faith in a code of laws that are put aside from human behavior.



Subsequently, liberals or nationalists could be considered to be as religious as Christians or Muslims. They as well have faith in a code of moral laws alike to laws of nature. These aren’t God-given; however, their origin isn’t made by humans as well. They as well are religious.

We still require religion. Science can’t provide solutions to everything, and it definitely can’t offer us a solution to ethical problems.

Assuming you wanted to make a dam. It could give energy to thousands of people; however, building it would leave a lot of families displaced. Science could explain how to make the dam well. However, it won’t respond to significant moral questions. Should the dam be made? Should those families suffer?

To respond to questions such as those, we still require a moral code. We still require religion.


Chapter 4 – Modernity entails that we can form our lives. However, has significance been lost?


The speed of change is rapid. We can now enhance our lives almost easily. However, in the process, something has been lost?

In the contemporary age, we have acquired power by refusing significance.

Long ago, we trusted in divine beings and that the world changed according to a master plan. This “script” offered life significance; however, it also restricted our power to act. This the reason we believed that disasters such as famine were a result of God’s will. The only answer was to pray, rather than of investigating more.

At the moment, we have dismissed the notion that such a script is real. We now understand that famine is a result of a series of connected and measurable incidences.

We have acquired power and we can write our own scripts. If we want, we can choose to invest in technologies to avoid future famines.

But, there’s a societal consequence; contemporary society is based on infinite development.



For example, funded research can make society better. Assuming a company wishes to produce a new fertilizer. The company requires bank credit for research. However, a bank can only provide assistance if it believes that it can profit eventually. In order for this belief to come true, the economy has to continue increasing. If not adequate people purchase the new fertilizer, the bankers question themselves, how will they ever get a profit on their investment?

This is the origin of modern human power: continued development and subsequent technological developments.

We send messages around the work immediately. In the olden era, this was power only the gods had! Nowadays, we can start to defeat death itself. If you desired, you could have your DNA sequenced for only $100 and make use of this genetic information to pre-emptively treat diseases and live more.

However, this raises the question, what have we actually acquired? Have we lost significance in this grab for power?


Chapter 5 – Liberal societies get significance from human experience and not God.


Now that we have taken out divine scriptures.  Therefore, from where precisely do we get profound meaning now?

Nowadays, it’s the human experience that discusses the significance of the universe. This is called humanism. It’s basically the main religion of the present society.

Humanism is essentially about mankind. Meaning, to discover meaning we need to “check within ourselves.”

As a result, it views a person’s experience as the foundation for power in society. Who is the person that chooses elections? The voter. And can we find beauty? Definitely, in the eye of the beholder.

There are various forms of humanism. The reason is that no one form has all-encompassing answers.

For example, how would you answer the question, do you have to fight for your country? Nationalists would answer in the affirmative. The reason is that they cherish their native citizens’ lives more than foreigners’ lives. What if you should take from the wealthy to feed the hungry? That would be fine with the Socialists since they value the collective more than a single person.

On the other hand, liberals would say no to both of the questions. The reason is that they believe to value every human experience equally.

These days, liberalism is the main form of humanism.



Starting from the early 1970s, liberalism extends all through the world from North-Western Europe and North America, at first to Asia then to Latin America and, after the destruction of the Soviet Union in 1991, then to Eastern Europe.

Really, there’s no actual substitute to the principle of liberalism nowadays. We work within its parameters. Even the alleged revolutionary movements are truly only advocating more liberalism.

Think of the Occupy Wall Street movement. Protesters grumbled that a few rich people had a major power over the markets. They asked for really free markets. That’s only liberalism by a different name!

However, confronted with more influential technologies, will liberalism be able to endure?


Chapter 6 – Contemporary science threatens liberalism at its core.


We are aware that liberalism is built on valuing human experience and individual liberty. However, how much do we actually understand about ourselves, the individuals? Contemporary science claims that we understand really little. Also, what we do understand barely supports the doctrines of liberalism.

For beginners, freedom is an ordinary illusion.

Liberalism is reliant on the belief of freedom. That’s the notion that individuals’ decisions are not fixed; however, given freely. This is the reason why individual decision (like voting) is seen as important.

But, according to contemporary neuroscience, choices are basically biochemical processes in the brain. These processes are no more the outcome of freedom than digestion or hair growing!

This is proven when we research with “Robo-rats.” When we send signals with implanted electrodes to a certain aspect of a rat’s brain, we can make choices for it. We can the rat to move to the right or left, or maybe jump from a height it wouldn’t usually try.

Aside from that, there’s nothing like “one true self.” This is a crucial notion in liberalism: it depends on the idea that there’s a true individual deep in every one of us.

Contemporary psychology verifies that this is an illusion.

The human brain consist of two hemispheres, left and right, joined by a single neural cable. For you to know how each of it works, psychologists have observed people whose association between the two hemispheres has been detached. As it turns out, the two parts have totally different functions.



Consider the study where a pornographic picture was revealed to the patient’s right hemisphere. They did this by making it noticeable to the patient’s left eye just because the right hemisphere interprets visual signals from the left eye and the other way round.

This is the exciting part. When displayed the picture, the patient gave a shy giggle. However, when she was asked the reason why she laughed, she didn’t have any idea.

Since the left hemisphere, which is in charge of rational descriptions, had not viewed the picture, the patient couldn’t rationally describe her act.

Eventually, the patient did come up with a reason for her laughter, saying that a piece of machinery in the room, which could be viewed by the left hemisphere,  seemed amusing. Amazingly, this occurs to every one of us regularly. Our left hemispheres are always functioning to make sense of incomplete information and to fill in unreliable stories.


Chapter 7 – One day, algorithms and technologies will control lives.


Contemporary science shakes liberalism to its core and makes its philosophical basics unsteady. However, humans are confronted with a more real threat: technology.

Humans are substituted every day by algorithms. The reason is that we want things to be finished very fast, effectively and consistently. This is the reason why computer algorithms are more and more chosen. Consider financial trading. One time the realm of the financier, at the moment it’s controlled by the microchip!

As we make more and more algorithms, it’s reasonable to claim that they’ll take charge ever more human duties.

What will be remaining for humans? Is there any work we do that could not be better accomplished by an algorithm?

The popular illustration here is art. Allegedly art will be human all the time. However, truly algorithms are producing it already.

Think of David Cope’s musical algorithm EMI. Cope is a Professor of Musicology from the University of California, Santa Cruz. His EMI program produced really efficiently that when its Bach-style pieces were listened to by music lovers, they couldn’t tell apart which one was EMI’s pieces and real Bach!



As time goes by, technology will decide more for us. As a matter of fact; already, technologies can observe our bodily data and make choices for us.

Let’s consider a study that was conducted in 2011 by Yale University. Researchers effectively tested an “artificial pancreas” for diabetics. A pump was put to the patient’s stomach, releasing insulin or glucagon anytime its sensors noticed risky blood sugar levels. The patient didn’t have an active role in the process.

Or think of how algorithms influence the manner we share information. Consider the data you share on Facebook: what you’re thinking, what you like, the person you like, the place you’ve been. The more we put in, the better Facebook understands us.

In 2015, Youyou, Kosinski, and Stillwell studied this. They discovered that with 300 “likes,” a Facebook algorithm could expect a subject’s responses to a personality questionnaire better than their partner.


Chapter 8 – As algorithms become more powerful, we need to choose. Fight back or allow them to succeed?


Honestly speaking, the increasing power of algorithms threatens our status as leaders of the planet. 

We have to come up with a strategy. However, what precisely?

One opinion is that we should unite with technology in order to keep pace with it. This is known as techno-humanism. By joining forces with technology, we could match the power of algorithms.

This is happening already. The US Army is creating an attention helmet already. This transfers electrical signals to certain components of the brain to assist soldiers to focus better for longer periods. This would make specialized soldiers, such as drone operators or snipers, as reliable as algorithms.

The kinds of technological advancements available will probably show our political and economic requirements. The attention helmet receives funding now since its clear military applications.

However, there’s a disadvantage. If we invest just in economically beneficial technologies we may turn into less empathetic people. Nevertheless, what is the significance of empathy for the growth economy?

A different new school of thought asserts that we should step back and allow algorithms to do their job. This is called dataism.

Dataism asserts that everything that occurs is either data or a data-processing system or algorithm. It is not important if it’s the position of the sun, a person’s political viewpoint, or your lover’s broken heart. Everything is only data.

As a matter of fact, humans, just like a computer or Google, are only data-processing systems. We process received data and utilize it to make choices. Thing such as grocery shopping is determined by hunger, the weather, the time or several other reasons.



Dataism knows history as only a process where we create ever-improving data-processing systems. As a result, according to dataism, it’s our responsibility as humans to create more efficient data-processing algorithms.

This leaves us with the huge question: What will take place when algorithms become superior at making data-processing algorithms than we are?

Are we then going to surrender our power? It’s not a comfortable opinion.


Homo Deus: A History of Tomorrow by Yuval Noah Harari Book Review


Our world is evolving and it will keep evolving. Our history as a species is formed on this change and development. If we have a better knowledge of our history and how it made us who we are now, we can have a more certain knowledge of where we will be in the nearest future.


Control the extent of your reliance on digital devices

Use a day without making use of your mobile device. Are algorithms already taking charge of your freedom?


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