The book surveys the history of humankind from the evolution of archaic human species in the Stone Age up to the twenty-first century. Its main argument is that Homo sapiens dominates the world because it is the only animal that can cooperate flexibly in large numbers. The book further argues that Homo sapiens can cooperate flexibly in large numbers, because it has a unique ability to believe in things existing purely in its own imagination, such as gods, nations, money and human rights. The author claims that all large scale human cooperation systems – including religions, political structures, trade networks and legal institutions – are ultimately based on fiction.
Other salient arguments of the book are that money is a system of mutual trust; that capitalism is a religion rather than only an economic theory; that empire has been the most successful political system of the last 2,000 years; that the treatment of domesticated animals is among the worst crimes in history; that people today are not significantly happier than in past eras; and that humans are currently in the process of upgrading themselves into gods.