Books Review: "Sapiens", "Homo Deus" and "21 Lessons For The 21st Century", by Yuval Noah Harari

post by Luca Parodi · 2021-10-13T16:21:50.048Z · LW · GW · 2 comments


    intersubjective myths
    three revolutions that created humanity
    three engines of history
  21 Lessons
    challenges of the new century
    and post-truth
    of the future
  Homo Deus
    class of the useless
    and techno-humanism
    are algorithms


In this review I will consider one of the most important literary and cultural phenomena of the last 20 years - the ambitious trilogy of the Israeli historian Yuval Noah Harari. In these three books Harari takes into consideration the past of humanity (Sapiens), the present (21 Lessons for the 21st Century) and the future (Homo Deus), trying to trace the global lines of development from the Stone Age up to the abandonment of biological bodies in favor of synthetic ones, passing through Trump and the future of unemployment. Among his greatest strengths as an author are:

There are undoubtedly more relevant and specific texts on each of the many themes addressed by Harari. Likewise, many of the observations in the texts can be (and have been) criticized from various points of view and for a variety of reasons, like Harari’s generalist approach and the lack of details. But precisely the horizontality and the ambitious scope are the main assets that make this trilogy so interesting and worth reading.

Observing a macro-trend from a hyper-specialized perspective can allow us to detail its different facets and potential origins, but makes it more complex to bring together different and broader contributions. Harari has chosen not to tackle the issues he faced from a hyper-specialized point of view, sometimes lacking detailed knowledge on certain topics, but manages to insert them within a universal narrative. A reader of Harari might find far-reaching insights into this narrative to ask questions about the research trajectories of his discipline and its role in a global perspective. 

The purpose of my review is to anticipate and facilitate this exercise of reflection. For each of these three texts I’ve summarized a small set of broad key ideas to keep in mind while reading. In conclusion, I will summarize some of the criticisms that have been made against the three books. 


The intersubjective myths

One of the starting points underlying Harari's entire body of work concerns the realm of intersubjectivity and its ability to concretely intervene on the world through the creation of myths. Between individuality and collectivity there is a third front, which is neither an objective fact nor a subjective impression, but resides in a sort of shared creative subjectivity. Harari defines this realm as an emergent property of the interaction between the single nodes of the collective, capable of creating a super-consciousness with a will of its own. From this dimension, a series of powerful intersubjective myths have emerged over the millennia, which as we will see in the book include laws, gods, money, morals, patriarchy and nations. They exist neither only in the natural world (although they refer to it), nor only in the non-shared imagination, but in shared intersubjectivity. To understand humans it is therefore necessary to understand the intersubjective myths we share.

This ability to create myths is what distinguishes Homo Sapiens from other species. It exists because we know how to use imagination and language to create and communicate new worlds, alternatives and future possibilities not physically present in the current reality. The function of such shared myths in our development was essential, as it allowed us to cooperate, organize ourselves on a large scale and dominate the world. Collectively they are the glue that holds societies together: they give meaning to existence and help make choices in a highly complex world. Let's look at two examples of collective myths:

In summary, therefore, it can be said that the intersubjective myths are the glue that holds culture and, consequently, society together. From this derives an essential consequence: breaking the myth means breaking the culture, and therefore the social world that relies on this myth, leading to a dramatic and rapid change. As we have seen in the past, breaking the myth of monarchy, slavery, or patriarchy means changing the cultural model of society. Slavery, for example, with all its premises about human nature and hierarchy, has been a widely accepted myth for a long time. By questioning this myth entire cultures slowly changed their views about the topic, leading to a series of social revolutions.

The last reflection linked to this idea concerns the (non-existent, for Harari) difference between natural and chemical/artificial. This distinction makes no sense: the chemical elements are the basis of nature. Paracetamol, petrol, blueberries, our saliva and a quasar are made of the same chemical elements. Consequently, everything Sapiens can do by modeling chemistry is, by definition, natural. Biology opens the way for changes; it is culture that closes us by forbidding certain behaviors and labeling them as unnatural. In a sense there is no difference between natural and artificial but only between possible and impossible. The study of human culture often covers the study of what we prohibit and how we box such prohibitions within natural/unnatural rhetoric.

The three revolutions that created humanity

Harari divides the history of man into three major revolutions, which as it will become clear in Homo Deus, will perhaps soon be followed by a fourth and more radical revolution. They are the cognitive revolution, the agricultural revolution and the scientific revolution.

The three engines of history

Another main theme of the book concerns the three main myths capable, according to Harari, of driving history. As always, following Harari, it is important to remember that each of these three engines actually has mythological foundations and does not represent anything tangible or material. It is possible to touch a coin and feel like we are touching “money” in itself, but a coin is just a symbolic representation of the concept. So there is no way to find a physical proof of the existence of nations, money or gods as concepts, but only as symbols of each concept. This does not mean, as already mentioned, that the effect of such intersubjective creations is not powerful. It is quite the opposite: these forces have been so powerful that they have shaped history indelibly.

21 Lessons

The challenges of the new century

In the central (and least original) book of the trilogy, Harari makes a series of reflections on a multitude of themes, trying to prefigure the main lines of development of this century. There are many issues addressed, and it would be impossible to focus on each of them in too much detail, so I will try to summarize only a few points of view.

Myths and post-truth

As stated earlier, according to Harari, the extreme complexity of the modern world is leading to the rebirth of religious extremism and identitarian movements. This, however, is not to be considered as large a danger as it might appear. In fact, while extremist movements can give a sense of purpose and a clear moral compass to the everyday lives of their adherents, they are unable to make sense of modern problems. How can reading a thousand years old sacred text give us answers on the future of Artificial Intelligence? How can the sense of national identity help us understand the developments in genetic engineering? The problem is that we do not yet have solid alternative myths that can speak to the majority of people and not just to hyper-specialized audiences.

Complicating the scenario is the great question of the excess of information available. When it is possible to instantly access every possible point of view and its opposite, how can we recognize what is true? From this question arose the idea that we live in the age of post-truth. In a sense, it no longer matters to the general public what is true and what is false, whether a scientific remedy works or not, or whether a theory is valid or invalid. What counts is the narrative behind these ideas and the way in which they adapt to our already existing vision of the world. According to Harari, as already seen abundantly in Sapiens, humans have always preferred narrative over truth, and have always been guided by myths. Post-truth, therefore, is a phenomenon as old as mankind, and has nothing to do with the upheavals brought about by Twitter and fake news.

This brings us back to the topic of creating myths. Given the potential upheavals caused by scientific rationality and its effects on society, it becomes necessary to rethink different ways of creating new myths, which will push people to re-evaluate their existence. In an interesting chapter of the book, based on an article published in Wired, Harari points out the crucial role that science fiction will have in this mythopoeic enterprise. A piece of fiction based on science but able to effectively tell the social and personal consequences of technological developments could be the key to creating new glueing myths? Could the role of films like Inside Out and Interstellar have a more important cultural function than a highly-cited physics paper?

Skills of the future 

A very interesting reflection concerns the most important skills that the inhabitants of the 21st century will have to possess, according to Harari. The transversal reflections on the theme cover more than one chapter. An important theory (but not the only one) states that the rate of acceleration of technological development and automation of tasks increases more or less constantly. If it’s true in the future the work we do today could become obsolete and the skills which we may have learned over the course of years useless in the job market, leaving us with a high probability of becoming unemployed. According to Harari, to get used to this frenetic pace of development it is necessary to teach the new generations more transversal skills, such as

Thinking about learning to program in Java to secure a long-term future immersed in PCs can be a huge miscalculation. On the other hand, those who focus on acquiring more transversal skills will be much more advantaged. Ultimately, however, one should not rely too much on these individual skills, as according to Harari they will all be more or less destined to be emulated by algorithms. The meta-skill par excellence is therefore flexibility, the ability to understand and grow in a world where it is impossible to make confident predictions about the future.

Homo Deus

The class of the useless

According to Harari, this century will be defined, among other things, by two driving forces.

From these two premises follows a rather disturbing argument, one of the book's main points:

The Marxist hypotheses about class struggle, in comparison, will be a nice thing of the past. Harari’s vision is bleak indeed: a scenario made up of semi-divine human beings, machines that do every job and billions of individuals drugged and immersed in virtual realities that distract them from the misery of their useless existence.

Dataism and techno-humanism

According to Harari, the myth capable of demonstrating the highest degree of cultural resilience in history has been (and still is) liberal humanism. Born from centuries of philosophical stratifications, since the end of the USSR it has established itself as a central value in almost the whole of the earth, leading thinkers such as Francis Fukuyama to speak about the "end of history". Liberal humanism is founded on democracy, capitalism and tolerance, and celebrates human intelligence, experience, values ​​and uniqueness. According to Harari, in the next century we will see a rapid decline of this value.

To narrate the decline of liberal humanism, Harari starts by describing the intersection of two new sets of values, one rooted in more extreme assumptions (which he calls Dataism) and a more moderate one (which he calls techno-humanism and which we could define as transhumanism).

According to Harari, the intersection between these two value systems will lead to the overcoming of humanism. We have realized that in order to achieve the techno-humanist’s lofty goals it is necessary to use a large amount of data about ourselves. By aggregating them to try to get to know them better or to make the right choice, the algorithms will guide us in everyday life, until they become an essential element in our life. If, therefore, the fundamental value of liberal humanism is that of autonomy and if we realized that this autonomy is less effective in achieving the highest goals than delegating our choices to a machine, what will remain of humanism? What will happen to independence and individualism in the face of the idea that something external to us will know us better than we know ourselves?

According to Harari, the triumph of data will defeat the domain of individual autonomy, and morality will take on completely new and unimaginable shades. What values ​​will an immortal post-human being, enhanced and fused with data processing systems, believe in? To think that such a being can base its ethical system on what the disciples of monotheistic religions or of the scientific revolution have taught us is naive, and the question remains open.

The last step of this trajectory concerns the creation of what Harari calls the internet-of-all-things. If everything is an algorithm, if reality is permeated with data to be processed and if this processing allows to achieve better results in everything, then it is easy to assume that the next result will be that of creating an internet that permeates the whole of reality, of an algorithm that is fused with every aspect of the planet, the galaxy or the entire universe. Obviously, here we are in the plane of pure science fiction speculation (or not?). But even the first steps towards the creation of this system will be the premise for the disappearance of Homo Sapiens.

Organisms are algorithms

An interesting chapter of this wild flight concerns the thesis, which Harari defines as "accepted by biologists", according to which organisms are nothing more than algorithms. This is a thesis with strong philosophical implications, which should be investigated more carefully, but on which the book relies heavily. The idea is that everything that makes up an organism can actually be decoded and analyzed as data. The emotions we feel, the thoughts we have, the decisions we make and the values ​​we believe in are the summation of a series of chemical impulses in the brain, caused by neuronal activation patterns defined in part by our past experiences and in part by our background genetics. Nothing more. There is no "magical" component behind what Sapiens, or any other species, are and do.

In light of this, it becomes very easy to imagine the continuation of the reasoning. If what we are is determined by a series of clear and quantifiable contributing causes, then it becomes automatic to try to decode them in order to try to improve them. We can break everything down, quantify it, analyze it and try to create an enhanced version of it. Even human activities generally considered more "subtle" become simple material to decode: the most sublime art arises not from the work of the Muses, but from the release of combinations of neurotransmitters at the root of pleasure linked to every note, stroke or rhyme. Decode these combinations, create a system to produce new ones and you will have created a Van Gogh 2.0.

This reasoning also supports the hypothesis of complete work automation very well. If everything is permeated with data and if that data can be interpreted effectively by perfect machines that can do impeccable jobs with them, what is left for humans? This argument could face an anti-reductionist philosophical critique of the central thesis according to which “organisms are algorithms”. Personally, I lean towards materialist and physicalist positions, but there is no doubt that such laconic sentences on such complex issues can be subject to numerous criticisms.

The final step of the whole reasoning is very simple: the era of Homo Sapiens is nearing its end. In its place we will see the birth of Homo Deus, something that we cannot yet describe, but which we know will originate from the exponential development of all the social, technological and cultural trajectories described in the three books of the trilogy.


This trilogy therefore offers us food for thought and many questions to answer. If those who have come to the end of this review should intend to launch themselves into the reading of the trilogy (personal advice: the three books lend themselves very well to audio reading) here are some general questions to keep in mind.



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comment by Vaniver · 2021-10-13T20:18:50.084Z · LW(p) · GW(p)

Sapiens was previously discussed on LW here [LW · GW] back in 2015.

comment by adamShimi · 2021-10-14T08:00:58.525Z · LW(p) · GW(p)

Haven't read the book and I'm not a historian, but I'm very dubious of any megahistories nowadays after reading so many criticisms of actual histoirans that point out how wrong the data generally is, and how badly the uncertainty is represented.

The AskHistorians subreddit is generally great for that (see this thread on Sapiens for example)