Harari divides the book into three broad sections.
In Part I, Harari argues that roughly 70,000 years ago, Sapiens took an evolutionary leap, almost by accident, that allowed them to develop consciousness and rise above all other species. For Harari, consciousness is nothing more than biochemical interactions in the brain that produce subjective experience, while much of our mental life – hunger, fear, loyalty, operates unconsciously (pp. 107–108). This raises a difficult question: Why do we even need consciousness? Some scientists argue that consciousness evolved for reflection, reasoning, and decision-making. Neil deGrasse Tyson, on his StarTalk program, is not convinced (StarTalk, March 14, 2024). Tyson notes that we have no credible measurement for consciousness, and that simple AI algorithms already perform tasks such as controlling, reasoning, and making decisions. If machines can do all of this without consciousness, then these abilities cannot explain why consciousness emerged in the first place. Some scholars even argue that conscious AIs already exist or will emerge within a decade (Chalmers, 2023). Others claim that early forms of “conscious” AI date back to the 1960s, though each time technology advances, we raise the bar and redefine what consciousness means. It is also worth remembering that primates, including monkeys and apes, possess consciousness. Perhaps it is language, not consciousness, that truly separates humans from other animals (Bennett, 2023). Language was the turning point that allowed cooperation among non-kin, the creation of shared values, and the formation of large communities. The agricultural revolution, beginning around 20,000 years ago, amplified this capacity. Harari closes Part I with a simple but profound question: In which direction are we heading?
Part II explores the brain, algorithms, and religion. Harari reminds us that the human brain contains more than 80 billion neurons, yet our understanding remains minimal (p. 111). He reduces the mind to a kind of algorithm, a systematic method for processing information, solving problems, and making decisions. From this perspective, algorithms also explain emotions and behavior. Yet the brain is not fully mechanistic; social, cultural, and religious forces shape human action in ways that complicate any attempt to model it. Harari then revisits the relationship between science and religion. Historically, religion created the social order that allowed science to flourish. Many scientific breakthroughs arose in deeply religious societies. Copernicus and Newton lived in cultures steeped in faith. The scientific revolution emerged within a religious setting, and the Industrial Revolution took root in one of the most devout societies in Europe. Harari concludes this part by stating that science and religion are not in contradiction. Both seek truth, integrity, and order. Religion, in his view, provided the framework that enabled scientific thinking. One of the most memorable lines in this section reads: “During our infinitesimally brief stay on our tiny speck of a planet, we fret and strut this way and that and then are heard of no more” (p. 201).
Part III examines the evolving relationship between technology, humanism, and the future of humanity. Harari argues that scientific progress has slowly eroded the need for God. Nietzsche declared “God is dead,” although it took centuries to bury the body. Humans invented God, wrote scriptures, and interpreted them endlessly. Yet despite the decline of religion, social order has not collapsed. Religion remains influential. According to Tyson, about 7% of Nobel Prize–winning physicists and biochemists still believe that their prayers are answered (StarTalk, 2016, February 14).
Harari asks whether artificial intelligence and biotechnology threaten humanism and examine the evolution of knowledge:
Medieval education relied on scriptures and logic:
Knowledge = Scriptures × Logic
The scientific revolution replaced this with:
Knowledge = Empirical Data × Mathematics
Humanism introduced a third formula:
Knowledge = Experience × Sensitivity. Experience, however, is subjectivity shaped by sensations, emotions, thoughts, and ideology.
- Liberals see each experience as unique and enriching.
- Socialists judge value based on social impact.
- Evolutionary humanists reject the idea that all experiences are equal.
Liberalism survived challenges from socialism by absorbing many of its ideas, including public education and social services. Even nuclear deterrence (MAD) helped preserve the liberal order. Harari also reminds us that the Soviet Union carried the heaviest burden in defeating fascism, losing roughly 25 million lives—far more than Britain and the United States combined. Liberalism rests on three assumptions: (1) I am an individual with a single essence. (2) My true self is free. And (3) Therefore, I can know myself better than anyone else.
Yet emerging technologies, especially biotechnology and algorithms—do not care about free will or personal identity. These innovations elevate a handful of individuals (the new czars of Amazon, YouTube, Microsoft, and others) while rendering millions economically irrelevant. Society may continue to benefit collectively while disregarding individuals. Harari does not fully explain how such a society would function, but he shows that modern innovators are accomplishing with nanotech and brain-computer interfaces what authoritarian regimes once attempted through force.
The driving force behind this transformation is the decoupling of intelligence from consciousness. For most of history, only conscious beings could perform intelligent tasks. Today, non-conscious intelligence already outperforms humans in many domains (creating the useless class). This creates an unsettling question: Are we entering an age of upgraded inequality? In 2016, 62 people owned as much wealth as the world’s poorest 3.6 billion. No one knows what 2070 will look like. Bennett (2023) argues that AI cannot replace humans unless it can process information like the human brain, and we can’t even imagine closing the gap in 100 years to come. Others agree with Harari that the mind remains uncharted territory and that future breakthroughs may offer new paths for advancement in AI technology that parallel or even surpass the human mind. It may even be possible for other species, e.g. bats, to evolve beyond us. Intelligent minds can emerge in countless forms, far beyond anything we currently imagine.
Reflection
Harari challenges the foundations of liberal democracy, individual rights, and free will. He argues that humans have no soul and no free will, we are biological machines made of algorithms, shaped by genetics, environment, and chance. Robert Sapolsky’s decades-long research reinforces this conclusion. From the moment we begin as a single cell, everything that follows is shaped by forces beyond our control. The causal chain never breaks; no neuron behaves contrary to its history. Harari adds that modern brain-scanning technologies can predict a person’s decision before that person becomes aware of making it.
If this is true, our current moral system is deeply flawed. We punish or reward people for behaviors rooted in biology and development, not choice. Meritocracy becomes questionable. Criminal justice becomes morally inconsistent. Children with autism or dyslexia are who they are because of neurological development—not decisions. Sapolsky argues that his theory can be disproved only by finding a neuron acting against its own history. So far, none exists. If his argument holds, society will need an entirely new moral code—one that protects public safety without punishing individuals for actions beyond their control.
Harari also raises difficult questions about the future. Science and technology advanced rapidly once intelligence decoupled from consciousness. Where do we go from here? Are we moving toward artificial brains and a new generation of intelligent machines? If so, can we upload our consciousness onto digital platforms? And even if we could, would the digital version be real, or an imitation? More fundamentally, can we ever recreate the human brain, an organ of staggering complexity that we barely understand?
Finally, Harari’s conclusion that religion is not an obstacle to science is, in my view, is not fully accurate. Neil deGrasse Tyson offers a more compelling historical example through the rise and decline of Baghdad (StarTalk, 2016, February 14). From the 8th to 13th centuries, Baghdad was a global center of science and engineering. Algebra, algorithms, and Arabic numerals flourished. Nearly two-thirds of the stars known today still carry Arabic names. But the theological shift led by Abu Hamid al-Ghazali (1058–1111) placed divine will above natural causation and discouraged speculative philosophy. This intellectual turn weakened the scientific spirit that once defined Baghdad. Although historians point to Mongol invasions and political collapse, the larger point remains. once religious authority overshadowed free inquiry, the scientific tradition never fully recovered. Islam revived as a powerful cultural and spiritual force, but without its scientific advancements. Neil Tyson made the following comparison: out of more than 1.3 billion Muslims, only two have received Nobel Prizes in the sciences; whereas a community of 15 million Jews accounts for roughly a quarter of all scientific laureates. The contrast is striking. It underscores one central idea: for science, and for AI, to flourish, religion must remain separate from government, education, and scientific inquiry. Whenever faith becomes the arbiter of knowledge, progress slows. Whenever free inquiry is protected, scientific inquiry and progress flourish.
References
Bennett, M. S. (2023). A brief history of intelligence: Evolution, AI, and the five breakthroughs that made our brains. HarperCollins.
Chalmers, D. J. “Could a Large Language Model Be Conscious?” Boston Review, 9 Aug 2023
Harari, Y. N. (2017). Homo deus: A brief history of tomorrow. HarperCollins
StarTalk. (2024, March 14). Neil deGrasse Tyson & Robert Sapolsky — Do we have free will?
[Video]. YouTube. https://www.youtube.com/watch?v=pFg1ysJ1oUs
StarTalk. (2016, February 14). Neil deGrasse Tyson vs. Al-Ghazali – On the Islamic Golden Age
[Video]. YouTube. https://www.youtube.com/watch?v=tcHPU-aOJAY