Homo Deus: A Blundering Tall Story of Tomorrow

Famine, plague and war will soon be problems of the past. Instead of deities, we will worship data flows. And overcoming death is only a question of time. You think these are daring statements and would like to see some profound back-up? Apparently it takes only about 500 pages to argue for these theses — or at least this is what Yuval Noha Harari attempts in his highly praised best-selling book ‘Homo Deus: A Brief History of Tomorrow’, where the historian aims to discuss realistic scenarios what the next decades for humankind might look like. Sounds intriguing? It surely is. However, before you head out to buy it give me the chance to make you aware of one thing about this book: the scientific foundation Harari bases his whole argument on is haywire.

Homo Deus paints a flawed picture of state-of-the-art biology, nanotechnology and medicine by misinterpreting, misusing or changing the content of scientific references. From this picture Harari infers daring predictions for the future of humankind. However, being built on misconceptions and false statements, the results of Harari’s reasoning should not be viewed as anything with realistic or truthful character.

Of course, you probably do not — and absolutely should not! — just blindly trust the claims that I am making. To find the first example you only need to read as far as page 15. Referring to a popular science book which is only available in Hebrew [1], Harari states that researchers have developed ‘nanorobots’ that can navigate through your blood vessels to identify and kill cancerous cells. In reality, the ‘bionic predators’ he mentions are DNA pieces or polymers used to transport drugs [2]. Bionic robots fighting cancer are a topic for a science-fiction book.

This is only the first, and comparatively minor, mistake. To save you some time and nerves working through the falsehoods in the book, I will point out more severe examples of misconceptions, wrong statements and reference abuse. I am not going to argue any of Harari’s predictions for the future since the starting point of the historian’s argument is plain wrong. Similarly, I would not advise anyone to engage in a discussion about the best sailing route from L.A. to Hong Kong with a person who is convinced that the Earth is flat. That would be a waste of time.

Harari’s History of Tomorrow

In case you have not read the book let me give you a rough idea what it is about: in Homo Deus Harari faces the question ‘Where do we go from here?’. Meaning, in the prospect of the faster and faster development of new technologies, where is humankind heading? Will humans — with the help of new technologies — upgrade themselves to deities with ‘supernatural’ powers? Will gods from traditional religions be forgotten? Will humans lose their meaning in the whole process and will artificial intelligence take over?

To answer these questions the first two thirds of the book review the evolution of the species of Homo Sapiens from its beginning up to the present day. The discussion of history and the understanding what kind of world we created is an important part, since generally, it is crucial to establish a proper understanding of the past, the present, and the processes driving evolution to make reasonable predictions for the future. Harari’s conjectures for different scenarios of our future, based on his understanding of the present, can be found in the third part.

The major pillars of the historian’s argument are that, for the privileged part of the Earth’s population, problems like war, famine, and diseases will soon belong to the past owing to advances in science. This will give scientists the time to focus their research on things like how to upgrade humans to cyborgs and to out-smart death. Harari’s predictions also heavily rely on the paradigm that ‘organisms are algorithms’ and that free will does not exist. He uses that to argue that all our actions and decisions are either deterministic or random, but not free; thus, he concludes, they are predictable. Hence, with enough data at hand ‘non-conscious but highly intelligent algorithms may soon know us better than we know ourselves’ [Chp.11, p.462]. Harari says that in the future machines will not only perform physical work more efficiently than humans, but might also replace us when it comes to cognitive tasks and decision making. For example, you can find statements like ‘Liberal habits such as democratic elections will become obsolete, because Google will be able to represent even my own political opinions better than I can’ [Chp.9, p.394]. Therefore, in the near future humanism might be replaced by ‘dataism’, the veneration of data flows. Leaving no meaning or purpose for the species of Homo Sapiens.

Throughout the whole book, Harari shows a somewhat out-of-touch attitude towards research in natural sciences. A statement representative of this is ‘.. every technical problem has a technical solution. We don’t need to wait for the Second Coming in order to overcome death. A couple of geeks in a lab can do it’ [Chp.1, p.26]. Being a physicist, I might be one of these ‘geeks in a lab’. Unfortunately, I do not see me or any of my colleges from neighbouring disciplines helping humankind to overcome death anytime soon. However, what I can do is point out the false statements in ‘Homo Deus’ and Harari’s misconceptions when it comes to natural sciences.

Science-Fiction instead of Scientific Foundation

So, if anything, what is wrong with the book? Here a few concrete examples:

Medicine — Antibiotics: Consequently, though in 2050 we will undoubtedly face much more resilient germs, medicine in 2050 will likely be able to deal with them more efficiently than today’ [Chp.1, p.15, the references for the statement are specialist literature from medical journals, 3–7]. This claim is used to argue that in the near future most (if not all) diseases can be cured and researchers can spend their time on things like overcoming death. Unfortunately, Harari’s statement does not agree with the state-of-the-art in the field. Some of the articles cited in the book contain general ideas on how to tackle the problem of the increasing resistance of bacteria to antibiotics. However, the scientists mainly advocate for trying to avoid infections in the first place and for a more cautious use of antibiotics. For example, ‘We hope that adding infection control and prudent use of antimicrobial agents to new drug development will avert the realization of pessimistic predictions about the future of antimicrobial resistance.’ [4] or ‘The situation is even more dire when it comes to nosocomial gram-negative infections, since no new antibiotics against these multidrug-resistant organisms are in advanced stages of clinical development’ [6]. These statements do not reflect what they are claimed to be a reference for.

Neuroscience — Free Will: Free will does not exist. Imposing that human actions are either random or deterministic, Harari concludes that they are predictable. This inferred predictability is one of the major pillars of the book’s reasoning. Harari states ‘Over the last centuries as scientists opened up the Sapiens black box, they discovered there neither soul, nor free will, nor ‘self’ and ‘The electrochemical brain processes that result in murder are either deterministic or random or a combination of both — but they are never free’ [Chp.8, p.328]. No reference is given for these statements. And the reason for that is fairly simple: there is none. Whether there is such a thing as free will or not is an ongoing debate among experts and subject to investigation with a whole research field devoted to it [see 8 for a summary and discussion of recent studies in the field].

One scientific back-up for the statement is given by referring to an experiment originally proposed and conducted by Benjamin Libet [9]: probands are asked to decide to press one out of two buttons and to report at which time they were conscious about their decision. Functional magnetic resonance imaging (fMRI) scans of the subjects’ brains suggested that the decision for which button to push was made up to a few seconds before the proband reported to be conscious about it [the references from the book are 9–11]. Nevertheless, these results do not prove the non-existence of free will; there are a number of up-to-date articles who question the suitability of Libet’s experiment set-up to test free will and the interpretation of the results. One would be ‘Why Libet’s Studies Don’t Pose a Threat to Free Will’ [12] by Adina L. Roskies, who holds a PhD in Neuroscience & Cognitive Science. And it is not hard to find more examples written by experts in the field [e.g. 8 or for a publicly available article 13].

The point is: the discussion on the existence of free will is far from being settled. It is unclear to me why the historian Harari thinks he has the competence to do so.

Neuroscience — Roborats: Harari discusses alleged up-to-date research results to demonstrate how far experts already have progressed in understanding and especially influencing the (human) brain. The first example are ‘roborats’: rats who can be steered by stimulating the reward centre in their brain. They can be trained to navigate through a maze on a specific path or climb up ladders on command. Referring to [14–16] Harari says ‘researchers have managed not only to make the rats turn left or right, but also to [..] do things that rats normally dislike, such as jumping from extreme heights’ [Chp.8, p.333]. Harari’s reference says ‘ [..] even continuous MFB stimulation cannot make a rat jump from a dangerous height’ [15]. I think there is no need to argue why it makes a huge difference whether you can stimulate a mammal’s brain to make it act against its instincts to directly put itself into danger, or whether you can not.

Treatment of Depressions: According to the book, doctors at the Hadassah Hospital in Jerusalem have implanted electrodes in patients’ brains that are connected to a computer in their chest which sends signals to the brain to ‘paralyse the brain area responsible for the depression’ [Chp.9, p.334]. Harari says ‘one patient complained that several month after the operation he had a relapse and was overcome by severe depression. Upon inspection the doctors found the source of the problem: the computer’s battery has run out of power. Once they changed the battery, the depression quickly melted away’, referring to ‘Smadar Reisfeld, ‘Outside of the Cuckoo’s Nest’, Haaretz, 6 March 2015'. Besides a proper reference to the researchers who actually conduct these studies, a link to the story with access date are also missing. You might think that Google can easily help out to find the article. Unfortunately it can’t. If you look for the reference and exclude ‘Harari’ as a keyword (to avoid only getting links to Homo Deus) I found exactly one relevant entry: the link to Smadar Reisfeld’s writer’s page on haaretz.com. It contains a list with her articles from the past years. An article named ‘Outside of the Cuckoo’s nest’ is not listed there. And according to Google also not anywhere else.

I did some more digging into this topic and found one other article on haaretz.com from 2012. At least this article mentions the names of the doctors involved in the alleged depression treatment but also lacks proper references. I looked at the recent publications of the named doctors, their pages on the Hadassah Hospital website and the ongoing research at the hospital. Even after spending a fair amount of time on this I did not find anything related to the claims Harari is making or the article ‘Outside of the Cuckoo’s Nest’ ( — an attempt to translate the title into Hebrew and searching for it also failed. But that might have had different reasons..). Of course, the fact that Google and I fail to find the reference does not mean that it does not exist. Nevertheless, I think the lack of a link, an access date, hits on Google and other reports related to Harari’s story speak for themselves.

If you are a Harari fan you might argue that I am just cherry-picking unfortunate examples. But the list is far from being exhaustive. I could keep elaborating on incorrect statements for several more pages. Just to mention a few: ‘Most natural systems exist in equilibrium’ — which they don’t*, ‘Bedpost sells biometric armbands which you can wear while having sex [..]’ — which it doesn’t**, ‘humans [..] find it difficult to believe in growth’ — which they don’t*** or ‘Google launched a sub-company [..] whose stated mission is to ‘solve death’ ’— which it didn’t.****

Additionally, I did not go into details about Harari’s misconception that the statement ‘organism X is acting according to an algorithm’ does not necessarily imply ‘I can predict the actions of organism X’.***** Moreover, I did not discuss the plot holes in the argument. One brief example would be: ‘[..] technology is not deterministic’ [Chp.11, p.461]. However, Harari assumes that humans act according to algorithms and are therefore predictable. Since technology is nothing but devices and algorithms built and implemented by humans, it is not clear to me why and where he is drawing a line from deterministic to non-deterministic processes.

The full quote about determinism of technologies is from the second to last page of the book and reads ‘We cannot really predict the future, because technology is not deterministic’. If you ask me, this is where he should have started the book. And finished it.

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 * Chp.6, p.238 — simple counter example: ongoing evolution which pretty much includes ‘most’ systems. 
** Chp.9, p.386 — at least if he is referring to www.bedposted.com. If not, whoever is selling these armbands does not have a great marketing strategy; I got nine hits on Google with ‘bedpost biometric armband sex’, three of them Harari related, two of them rated R.
*** Chp.6, p.239 — the part of the population that is investing into the stock-market at least surely does believe in growth.
**** Chp.1, p.28 — according to the company’s website www.calicolabs.com their mission is to ‘[..] enable people to lead longer and healthier lives’.
***** To see that you can consider a counter example: a fluid floating through a pipe. Even though we know the physical forces and laws that apply very well (i.e. the ‘algorithm’ according to which a single particle acts) it is still unknown how to describe the systems once the internal energy crosses a certain threshold and turbulences occur. This problem, related to the solutions of the Navier–Stokes equations, is in fact one of the ‘Millennium Prize Problems’ from the Clay Mathematics Institute.

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The Bungled Creation of Homo Deus

How come Homo Deus turned out so wayward? — It is a book attempting to give a realistic outlook into the future of humankind, which makes it heavily dependent on a detailed understanding of state-of-the-art research of scientific disciplines, like biology, neuroscience or medicine. Given the mistakes, Harari does not convince to have an understanding of the results from any of these fields. Or maybe he does. But if his blunders are not the result of careless work, honest mistakes and/or ignorance, I can only see one more explanation for the falsehoods in the book: a deliberate deception of the reader. But this is not for me to judge.

Owing to Harari’s mistakes Homo Deus can be revealed at best as boring Science-Fiction. It is sad to see a book of this caliber not only pass the publication process, but also being listed on the Time Magazine’s List of the ‘Top 10 Non-Fiction Books of 2017’. If you wish you may praise Homo Deus for an ingenious use of rhetorical devices or insights into history. I do not have the competence to assess that. But a list with ‘Non-Fiction Books’ is not a list it belongs on.

Harari is about to publish his new book ‘21 Lessons for the 21st Century’. Hopefully, he goes back to what he must have learned during his PhD studies in Oxford and obeys the basic principles of scientific work and research. If not, I sincerely hope that reviewers as well as readers will pay more attention to his statements, to not give another book full of mistakes and false claims undeserving credit.

So what will happen? I am not as bold as Harari and dare to make any involved predictions how the future for humankind might look. But if we keep allowing people to get attention and glory by spreading intriguing sounding falsehoods, our species of Homo Sapiens (lat. ‘knowing man’) will probably not turn into Homo Deus (lat. ‘god-like man’) but rather into Homo Fallens (lat. ‘deceiving man’).