Sapiens by Yuval Harari (Book Review)

I recently finished Sapiens by Yuval Harari, which is subtitled “A Brief History of Humankind.” I highly recommend reading Sapiens even though I have a fundamental disagreement with one of Harari’s core premises. 

Let’s start with what’s great. The book delivers on its madly ambitious subtitle by in fact managing to cover key moments in the developmental history of humankind from the emergence of Homo Sapiens to today’s developments in genetic engineering. It does so in easily accessible language and with many clever turns of phrase and bold chapter titles such as “History’s Biggest Fraud” (about the agricultural revolution). Harari also does a marvelous job with specific examples and dramatized historical moments including some imaginary dialog that keep one engaged as a reader. It also helps that the book has some beautiful illustrations and is printed on extremely heavy stock. All of it adds up to a compelling experience the big picture of history – even if you know a lot already you will discover new connections and perspectives. If you don’t want to read you can watch Harari cover the material on Youtube

I have some minor quibbles. For instance, early in the book Harari points out that the evidence from pre-history about social behaviors is rather limited and hence it is hard to know much about what families looked like for much of our early evolutionary history. Later, in covering industrialization he observes that one of the biggest cost of industrialization has been the collapse of the nuclear family. But maybe early families weren’t nuclear at all as at least some of the pre-history evidence suggest. Another example of such an internal inconsistency is that Harari has a great section on how bloody Christian on Christian violence was during the Thirty Year War but in a later section he supports the assertion that we live in the most peaceful time ever by arguing that the cost of war has gone up and its benefits down. That is obviously irrelevant to any war based on faith. As an aside, the statistics on the decline of violence are badly biased because of tail risk and have Harari commiting an example of what he earlier in the book calls “The Hindsight Fallacy.” I should add that as I am working along on my own book I have developed a first hand appreciation of how hard it is to avoid these kind of inconsistencies.

My real objection, however, is to a central assertion. Harari claims that all human narratives, including all religions and ideologies, are entirely inter-subjective. In his chapter on Humanism, titled “The Worship of Man” Harari writes (p. 230)

Humanists believe that the unique nature of Homo Sapiens is the most important thing in the world, and it determines the meaning of everything that happens in the universe.

He then goes on to argue that this too is simply an inter-subjective belief that cannot be justified on an objective basis. It is just another narrative like those that had kings as rulers whose power derives from Divine Providence.

But there is an objective criterion by which humans are equal to each other and are different from all other species: we have knowledge. In my definition, knowledge is the distinctly human ability to externalize information and maintain and evolve that externalized information over many generations (this includes science but also art and music). I have written previously about how the possibility and existence of knowledge provides a purpose for humanity but it has only recently occurred to me that this is the proper justification for humanism.

If you don’t like my definition of knowledge you can revert to a more accepted principle which is Turing’s insight into computation. Every human equipped with a pen and paper is a “universal” computer (a slow one yes, but universal nonetheless). What does that mean? It means that there is nothing that can be computed by any machine that we know how to build given existing physics that couldn’t be computed by a human given enough time (and enough pencils and paper). Put differently we are all at least equivalent to Turing machines. But no animals are. I have been thinking about what this means for our values recently and will write more about that – “with great power comes great responsibility” definitely applies.

Humanism does have an objective foundation in our understanding of computation. Read Sapiens for an amazing ride through history. Then come back here and read more about a humanist vision for the future.