The book compares East and West across the last 15,000 years, arguing that physical geography rather than culture, religion, politics, genetics, or great men explains Western domination of the globe.

Morris' Social Development Index considers the amount of energy a civilization can usefully capture, its ability to organize (measured by the size of its largest cities), war-making capability (weapons, troop strength, logistics), and information technology (speed and reach of writing, printing, telecommunication, etc.).

The evidence and statistical methods used in this book are explained in more detail in Social Development,[1] a free eBook, and by the published volume, The Measure of Civilization.

"[7] The book has been criticized by the controversial historical sociologist Ricardo Duchesne for offering a 'diffuse definition of the West which Morris envisions encompassing not only Europe but all civilizations descending from the Fertile Crescent, including Islam, as well as a propensity to level out fundamental differences between the development of the West and the rest, which disregards the singular role of Europe in shaping the modern world'.

[8] Morris replied, saying that "despite his review’s length, rather little of it takes on my book’s central thesis", and defending his focus on China.