A Harvard historian, film-maker and journalist, Ferguson is known for his provocative, contrarian views. “The Great Degeneration: How Institutions Decay and Economies Die” is his latest book. “The Ascent of Money,” a recent documentary series, won the International Emmy award. He is writing a life of Henry Kissinger.

...History is like an oil tanker. It does not turn on a dime. Mankind sails forward through time in seas that are sometimes calm, sometimes stormy. At times it seems almost becalmed, at other times it can do 12 knots. Depending on who captains the ship, it veers sometimes to port, sometimes to starboard. When it changes direction, the turn is generally slow.

The things that change suddenly on an oil tanker are the emotions of the crew. Nine hundred and ninety-nine days out of a thousand, they obey their orders and do their work. But very occasionally there is a drama. The men mutiny and the captain is clapped in irons. Or pirates board the ship. Such events are what historians love to study and call “revolutions.” Still, the ship plows onward.

In other words, do not expect 1989 to happen every year — and don’t exaggerate how big a turning point even 1989 was. Nearly a quarter of a century ago, Francis Fukuyama hailed “an unabashed victory of economic and political liberalism… the Triumph of the West.”

It seemed so true. Who could forget the thrill of that night — Nov. 9, 1989 — when the Cold War ended not with Armageddon but with a street party? Yet, as I write, the People’s Republic of China is poised to overtake the United States in terms of gross domestic product (adjusted for differences in purchasing power) in 2017. If you invested in the West in 1989 you fared much worse than if you had invested in the Rest. Emerging stock markets have risen by a factor of five since 1989; the U.S. market, fourfold; Europe, less than threefold....