A third bit of conventional wisdom from the 1970s is that Asia generally and China in particular could never grow because of the burden of overpopulation.

But Asia’s state-led capitalism and Deng Xiaoping’s adoption of that model in 1978 has made Asia the growth capital of the world. Hundreds of millions have risen from poverty.

As for the population bomb, the biggest problem for Asia and China today is low birth rates and a contracting work force. These stopped growth in Japan and may do so elsewhere.

A final thing taken for granted in the 1970s was the enduring strength of the Soviet Union. It was, after all, ramping up its military even as America was recoiling from defeat in Vietnam.