DEEP READING · READ 8
Homo Deus: A Brief History of Tomorrow · Yuval Noah Harari · 2015
Sapiens told the story of how an unremarkable ape clawed its way to the top of the food chain; Homo Deus picks up where it left off and asks: once famine, plague, and war — the three ancient enemies that haunted us for millennia — are basically under control, what will a well-fed humanity want next? Harari's answer: it will turn its tools on itself and try to upgrade into a god, reaching for immortality, bliss, and the power to create life. But the book's real hook is a reversal: the very humanist creed that lifted the individual to sacred status is being dismantled, from its foundations up, by the science it hatched — life is just algorithms, free will is an illusion — and humans may well hand over both authority and meaning the moment we build algorithms that understand us better than we understand ourselves.
Harari is an Israeli historian at the Hebrew University of Jerusalem, trained in medieval and military history. His 2011 book Sapiens carried him from the seminar room onto global bestseller lists, and this 2015 sequel runs the same logic forward: the first book looked back to explain how humanity got here; this one extrapolates ahead to ask where we are going. He is not a scientist generating fresh data but a synthesizer — someone who stitches biology, history, AI, and economics into one sweeping narrative. That is both his greatest gift and his most-criticized weakness (see the final section). Read with one thing in mind: this is not a prophecy but a warning — Harari insists repeatedly that he describes these grim possibilities precisely so they won't come true.
The whole book compresses into three sentences:
This is the book's launch pad. For thousands of years, Harari says, humans treated famine, plague, and war as inescapable fate — divine punishment, the iron law of nature, met only with prayer. But in the 21st century these three, for the first time, shifted from "fate" to "technical problem": famine today is mostly a matter of distribution and politics, not absolute scarcity; when a plague strikes, scientists sequence the virus in weeks and produce vaccines in months; and more people now die from eating too much than from eating too little, and more die by suicide than from war, crime, and terrorism combined. (His one-line summary: sugar is now more dangerous than gunpowder.)
With the old enemies in retreat, humanity won't simply rest content — it will turn the same engineer's mindset on itself and set three new goals. Immortality — more precisely amortality: not literally never dying, but breaking death down from "God-ordained destiny" into a series of fixable technical glitches (cancer, the heart, aging), each one mended in turn. Bliss: turning happiness from a stroke of luck into a state that can be reliably manufactured by biochemical means (drugs, neural tuning) — if suffering is at bottom a biochemical signal, then in principle it can be re-tuned. Divinity: using bioengineering, human-machine fusion, and inorganic life (AI) to upgrade Sapiens into a being with godlike powers to create and destroy. What matters is not whether these goals are reached by any given year, but that they have already become civilization's default direction of travel — and the mere pursuit of them is enough to turn human society inside out.
This is the master key to the book, and the section readers most often skim past. Harari gives "religion" an extremely broad definition: any story that confers superhuman legitimacy on a human social order is a religion — it needn't involve a god, so long as it claims its rules come from some higher source no human may question. By that definition, liberalism, communism, and capitalism are all religions too.
So which has been the most successful religion of the last three centuries? Humanism. Its revolutionary move was a relocation of authority: in the age of God, the final verdict on meaning and morality lived in heaven — what scripture said, what the priest ruled, was right. Humanism took that verdict away from God and handed it to "human feeling." The supreme commandment of the modern world became "listen to your heart," "be true to yourself," "the customer is always right," "the voter knows best": beauty no longer sits on God's scale but "in the eye of the beholder"; meaning is no longer dispensed by scripture but generated whenever "I feel it's meaningful." This logic soaked into modern ethics (judge good and evil by feeling), politics (one person, one vote, because everyone's feelings count), economics (the customer is sovereign), and aesthetics (if I like it, it's good).
Humanism later split into three great sects, and the bloodshed of the 20th century was essentially a civil war between them. Liberal humanism: each individual's freedom and feelings are sacred and inviolable — dominant today. Socialist humanism: individual feelings can be brainwashed and misled, so look to the condition and equality of the whole collective, placing the party and the group above the individual. Evolutionary humanism: humans are not equal, some groups are "superior," with Nazism its extreme form. What they fought over was not "should we put humans first" but "which humans, and which part of the human, comes first" — which only shows how completely humanism had become the shared air everyone breathed.
Harari distills exactly what kind of bargain "modernity" is in one crisp phrase: humanity signed a contract — give up "meaning" in exchange for "power." Pre-modern people lived inside a cosmos whose script was already written: everything had its place, suffering carried its own purpose, the individual was one bolt in a grand cosmic plan. That gave people meaning, at the price of accepting their lot and never overstepping. Moderns flipped it: the cosmos has no script, no plan, and suffering is just meaningless bad luck — but precisely because there is no ceiling overhead, humans can acquire unlimited power to remake the world. Stripped of God-given meaning, the modern economy survives only on a new faith — growth: the belief that tomorrow's pie will be bigger than today's, which is the only reason we dare borrow, invest, and mortgage the future.
But here is the catch: if humans gave up meaning, who fills the vacancy? The answer is the humanism of the previous section — when God exits, "Man" himself takes the empty throne, using "human experience is most sacred" to re-inject meaning into a cosmos that has none. This is why Harari calls humanism the true religion of modernity: it isn't atheism, it is swapping God for Man.
This is the book's detonator, and the first charge under humanism's foundations. The reigning assumption of contemporary life science is that organisms are algorithms; emotions, desires, and feelings are not the mystical activity of a soul but biochemical computations honed by billions of years of evolution to make decisions. Fear is the "flee now" algorithm, disgust the "don't eat that" algorithm, love and jealousy algorithms about reproduction. It sounds cold, but it lands squarely on humanism's weak spot — because humanism bets everything on "human feeling is sacred," yet if feeling is merely an algorithm's output, what makes it sacred?
The second, sharper cut targets the "self." Humanism assumes each person harbors a single, free, authoritative "true self." Neuroscience says there is none. Split-brain experiments: in patients whose corpus callosum (the bridge between the hemispheres) has been severed, the left and right brains act independently and even fight each other — there is more than one "I" inside. Kahneman's famous pair, the experiencing self (the you feeling things second by second) and the narrating self (the you that afterward tells the story, assigns the score, makes the decision), drives it home: what we take to be "I" is really an in-house commentator in the brain, spinning a heap of disunified, often self-contradictory algorithms into one coherent "I." Harari coins a word for it: a human is not an indivisible "individual" but a divisible "dividual." And free will? It collapses too in the scientific picture: every "choice" of yours is computed by genes and neurons without your noticing — you merely claim it afterward and mistake it for "something I freely decided."
This is the book's most memorable — and most consequential — stroke. First, untangle two words people routinely confuse: intelligence is the ability to solve problems and reach goals; consciousness is "having feelings" — pain, love, the subjective "what it's like" of seeing red. Across all of evolutionary history the two were bundled together: the only chess-playing, poem-writing, surgery-performing high-intelligence beings on Earth happened also to be conscious creatures, so we assumed "the smarter something is, the richer its inner life."
AI has, for the first time, pried them apart: computers display superhuman intelligence on more and more tasks with not a shred of consciousness — a machine wins the game without knowing what "winning" means or tasting the victory. The economic and political fallout is seismic: armies and markets have always wanted the intelligence that "gets the job done," not the consciousness that "has an inner life." So once algorithms drive, diagnose, trade, translate, and write better and more cheaply than people, human economic and military value evaporates — not because some evil robot replaces you, but because you are quietly ruled "superfluous." Harari gives this group a stinging name: the useless class — not the unemployed (who can't find a given job) but a whole stratum no longer needed in any economic sense. The central injustice of history was "useful but exploited"; the real future dread is "not even worth exploiting." Worse, the few who can afford the upgrades — genetic, brain-machine, anti-aging — may diverge from the un-upgradeable masses into two biological species: an unprecedented inequality written into the flesh.
This is the book's terminus and its boldest move. A new religion, Harari says, is quietly taking shape in Silicon Valley and the labs; he calls it Dataism: it holds that the entire universe is a flow of data, and the value of any phenomenon or any life is measured solely by how much it contributes to "information processing." In this faith, free markets, democratic elections, genomes, and symphonies are all data-processing systems; humanity's historic mission is merely to build a system of all-connected, ubiquitous computation — call it the Internet-of-All-Things.
Dataism pushes humanism's own logic to the point where it dissolves itself. Humanism says "follow your feelings"; Dataism says "follow the algorithm" — because it has more data and more computing power, and understands your feelings better than you do. You already practice it without noticing: you let an algorithm pick your songs, a map pick your route, an app pick your partner, and you start reading even "how do I feel today" off a wristband. The instant you genuinely believe "Google / some algorithm knows what I want better than I do," that once-inviolable "inner self" cedes the throne, and authority completes its final relocation from "Man" to "data." And Dataism's coldest corollary is this: once humanity completes its historic task of weaving the cosmos into one data network, we ourselves — these slow, low-throughput carbon devices — may be gently retired, like the mammoths before us. Harari isn't saying this must happen; he is saying that when "the free flow of information" itself becomes the supreme good, humans cease to be the end and dwindle into a transit pipe in the torrent of information.
This concept carries over from Sapiens and is the underlying hardware holding the whole book up, so it's worth getting right. Harari asks: by what right do humans rule the Earth? Not because any single human is smarter or stronger (in a fistfight a chimpanzee wins), but because only Sapiens can cooperate "in vast numbers AND with great flexibility." Bees are numerous but rigid; chimps are flexible but can't muster a few hundred to work as one; only humans can get millions of strangers to toil for the same cause.
How? By jointly believing in "stories" that exist nowhere in the physical world, only in our shared imagination. Harari sorts reality into three layers: objective reality (stones, gravity — there whether you believe in them or not); subjective reality (my toothache, present only in my own mind); and the crucial intersubjective reality — money, nations, corporations, gods, human rights — which exist neither at the level of atoms nor inside any single head, but live in the shared imagination of millions: so long as enough people believe together, the thing can really mobilize resources, organize action, and decide life and death. A banknote is a printed slip of paper, yet because the whole world agrees it can be swapped for bread, it becomes the strongest cooperative glue there is. From this Harari loosens the grip of the word "religion": money, nations, and limited-liability companies are, at bottom, just like gods — fictions humans invent and that then organize the humans back. This also plants the dread that runs through the book: if even "the free individual" and "sacred human rights" are merely a story we happen to believe, then when Dataism — a new story — proves more useful, the old story gets replaced without any conspiracy at all; it's enough that people slowly change their faith.
Harari devotes a whole chapter to how humans treat animals, and it is no digression. After the Agricultural Revolution, humans compressed the lives of pigs, cattle, and chickens into suffering components on an assembly line, justified by a confident creed: animals are just soulless biochemical machines with no inner life, so use them however you like. He argues that industrial farming may be the largest-scale crime in history. But the chapter's true edge is a reflexive question: the very story we use today to demean animals and excuse their exploitation — "they're nothing but algorithms, with no real self or feelings" — is the same story contemporary science is now using to describe "humans." In other words, the logic by which humanism enthroned Man and reduced animals to machines will, under Dataism, swing right back onto humans themselves: the way we regard pigs today is the way a superintelligence may regard us tomorrow. The verdict "it's only an algorithm," handed down on animals, is becoming the verdict on humanity itself.
The book's three parts form one escalating "if-then" argument, not a chapter-by-chapter chronicle:
Threaded into one line: humans were crowned by fictional stories, gave the world meaning through the story called humanism, and will yield the throne to algorithms because science exposed that very story.
① The three old enemies — famine, plague, and war — are being demoted from "fates only God can lift" to "manageable technical problems"; today more people die from overeating than starvation, and more by suicide than by violence.
② A well-fed humanity will turn the engineer's mindset on itself and set three new goals — immortality, bliss, divinity — upgrading Sapiens into Homo Deus.
③ Modernity is a bargain: give up "meaning" in exchange for "power"; stripped of God-given meaning, the economy survives only on the new faith called "growth."
④ The true dominant religion today is humanism — it took the authority God vacated and handed it to "human feeling": listen to your heart, the customer is sovereign, the voter knows best.
⑤ Humans rule the Earth only through "intersubjective reality" (money, nations, gods, human rights — stories that live solely in shared imagination), which lets millions of strangers cooperate flexibly.
⑥ Contemporary science is knocking out humanism's foundations: life is just algorithms, free will is an illusion, and there is no single, free "self" — "I" is merely an after-the-fact commentator in the brain.
⑦ For the first time, intelligence (getting the job done) decouples from consciousness (having feelings): AI wins the game without tasting victory — and markets and armies want only the intelligence, not the consciousness.
⑧ Hence a "useless class" — not the unemployed but a whole generation no longer needed economically; history's old pain was "being exploited," the future's new dread is "not even worth exploiting."
⑨ A new religion, Dataism, arrives: the universe is a data flow, a thing's value lies only in its contribution to information processing; the moment you truly believe "the algorithm knows me better than I do," authority passes from humans to data.
⑩ We excuse exploitation with "animals are just algorithms with no inner life," yet science is applying that same verdict to us — the way we regard pigs today is how a superintelligence may regard us tomorrow; this is not a prophecy but an alarm telling us to figure out "what we actually want" before it's too late.