Economists believe in markets. Market-determined prices allocate scarce resources efficiently, encouraging individuals to put them to their best possible uses. This improves the welfare of ­everyone. But there are times when private markets break down, and insurance is one of them. When markets fail, the government inevitably has to step in to provide insurance. The future is one in which healthcare will fall into this same category. Even in countries like the US, the government, not the market, will ultimately control the level and cost of the medical care we will receive.

A single-payer, publicly run health-care system is the inevitable consequence of the nearly continuous scientific revolution in molecular genetics that began a half century ago. One day it is James Watson, one of the discoverers of the structure of DNA, being handed the complete genetic code inside his own cells. The next day researchers tie yet another chronic disease to the presence of specific patterns on individual chromosomes. Then, a few days after that, we find out that scientists are learning to make stem cells from skin cells.