21 Lessons for the 21st Century

Harari's third book addresses the present rather than the past or the future, and is organised as twenty-one essays across five sections covering technological challenge, political challenge, despair and hope, truth, and resilience. The technology essays argue that the combination of biotechnology and machine learning threatens liberal democracy's foundational assumption that individual choice is authoritative, because systems that know a person better than they know themselves can predict and manipulate their decisions. He also raises the prospect of a large class of people who are economically irrelevant rather than exploited, which he argues is a novel political problem without historical precedent.

The political essays address the failure of nationalism, religion and traditional ideologies to address problems that are global by nature, specifically nuclear weapons, ecological collapse and technological disruption, and argue that no national government can address any of them alone.

The essays on truth cover post-truth politics, arguing that humans have always organised around fictions and that the current moment is not exceptional, and cover the responsibility of individuals in an information environment designed to capture attention. The final essays cover education, arguing that specific knowledge is a poor investment when the relevant knowledge changes within a career, and meditation, where Harari describes his own practice.

The book is a collection of essays adapted from journalism and it repeats material from his earlier books substantially. The arguments are stated confidently without much supporting evidence, and specialists in each area find the treatment shallow. Its value is as a compact statement of the questions rather than as analysis of any one of them.