Yuval Noah Harari's "Homo Deus": Sweeping, clever and provocative, but speculative and incomplete

Yuval Noah Harari's "Homo Deus" continues the tradition introduced in his previous book "Sapiens": clever, clear and humorous writing, intelligent analogies and a remarkable sweep through human history, culture, intellect and technology. In general it is as readable as "Sapiens" but suffers from a few limitations.

On the positive side, Mr. Harari brings the same colorful and thought-provoking writing and broad grasp of humanity, both ancient and contemporary, to the table. He starts with exploring the three main causes of human misery through the ages - disease, starvation and war - and talks extensively about how improved technological development, liberal political and cultural institutions and economic freedom have led to very significant declines in each of these maladies. Continuing his theme from "Sapiens", a major part of the discussion is devoted to shared zeitgeists like religion and other forms of belief that, notwithstanding some of their pernicious effects, can unify a remarkably large number of people across the world in striving together for humanity's betterment. This set of unifying beliefs is not just religious or supernatural; even a completely secular concept like human rights refers to ideas which are nowhere to be found except in the human imagination. It is this zeitgeist of beliefs which is partly what jump-started the cognitive revolution that made Homo sapiens so unique. It has created or enriched an almost infinite variety of human institutions and ideas, from money and mating to democracy and disco music. As in "Sapiens", Mr. Harari enlivens his discussion with popular analogies from current culture ranging from McDonald's and modern marriage to American politics and psychotherapy. Mr. Harari's basic take is that science and technology combined with a shared sense of morality and our belief-generating cognitive system have created a solid liberal framework around the world that puts individual rights front and center. There are undoubtedly communities that don't respect individual rights as much as others, but these are usually seen as challenging the centuries-long march toward liberal individualism rather than upholding the global trend.

The discussion above covers about two thirds of the book. About half of this material is recycled from "Sapiens" with a few fresh perspectives and analogies. The most important general message that Mr. Harari delivers, especially in the last one third of the book, is that this long and inevitable-sounding imperative of liberal freedom is now ironically threatened by the very forces that enabled it, most notably the forces of technology and globalization. Foremost among these are artificial intelligence (AI) and machine learning. These significant new developments are gradually making human beings cede their authority to machines, in ways small and big, explicitly and quietly. Ranging from dating to medical diagnosis, from the care of the elderly to household work, entire industries now stand to both benefit and be complemented or even superseded by the march of the machines. Mr. Harari speculates about a bold vision in which most manual labor has been taken over by machines and true human input is limited only to a very limited number of people, many of whom because of their creativity and demand will likely be in the top financial echelons of society. How will the rich and the poor live in these societies? We have already seen how the technological decimation of parts of the working class was a major theme in the 2016 election in the United States and the vote for Brexit in the United Kingdom. It was also a factor that was woefully ignored in the public discussion leading up to these events, probably because it is much easier to provoke human beings against other human beings rather than against cold, impersonal machines. And yet it is the cold, impersonal machines which will increasingly interfere with human lives. How will social harmony be preserved in the face of such interference? If people whose jobs are now being done by machines get bored, what new forms of entertainment and work will we have to invent to keep them occupied? Man after all is a thinking creature, and extended boredom can cause all sorts of psychological and social problems. If the division of labor between machines and men becomes extreme, will society fragment into H. G. Wells's vision of two species, one of which literally feeds on the other even as it sustains it?

These are all tantalizing as well as concerning questions, but while Mr. Harari does hold forth on them with some intensity and imagination, this part of the book is where his limitations become clear. Since the argument about ceding human authority to machines is also a central one, the omission also unfortunately appears to me to be a serious one. The problem is that Mr. Harari is an anthropologist and social scientist, not an engineer, computer scientist or biologist, and many of the questions of AI are firmly grounded in engineering and software algorithms. There are mountains of literature written about machine learning and AI and especially their technical strengths and limitations, but Mr. Harari makes few efforts to follow them or to explicate their central arguments. Unfortunately there is a lot of hype these days about AI, and Mr. Harari dwells on some of the fanciful hype without grounding us in reality. In short, his take on AI is slim on details, and he makes sweeping and often one-sided arguments while largely skirting clear of the raw facts. The same goes for his treatment for biology. He mentions gene editing several times, and there is no doubt that this technology is going to make some significant inroads into our lives, but what is missing is a realistic discussion of what biotechnology can or cannot do, and what aspects of the field are likely to be impacted through gene editing. Similarly, it is one thing to mention brain-machine interfaces that would allow our brains to access supercomputer-like speeds in an offhand manner; it's another to actually discuss to what extent this would be feasible and what the best science of our day has to say about it.

In the field of AI, particularly missing is a discussion of neural networks and deep learning which are two of the main tools used in AI research. Also missing is a view of a plurality of AI scenarios in which machines either complement, subjugate or are largely tamed by humans. When it comes to AI and the future, while general trends are going to be important, much of the devil will be in the details - details which decide how the actual applications of AI will be sliced and diced. This is an arena in which even Mr. Harari's capacious intellect falls short. The ensuing discussion thus seems tantalizing but does not give us a clear idea of the actual potential of machine technology to impact human culture and civilization. For reading more about these aspects, I would recommend books like Nick Bostrom's "Superintelligence", Pedro Domingos's "The Master Algorithm" and John Markoff's "Machines of Loving Grace". All these books delve into the actual details that sum up the promise and fear of artificial intelligence.

Notwithstanding these limitations, the book is certainly readable, especially if you haven't read "Sapiens" before. Mr. Harari's writing is often crisp, the play of his words is deftly clever and the reach of his mind and imagination immerses us in a grand landscape of ideas and history. At the very least he gives us a very good idea of how far we as human beings have come and how far we still have to go. As a proficient prognosticator Mr. Harari's crystal ball remains murky, but as a surveyor of past human accomplishments his robust and unique abilities are still impressive and worth admiring.