When did capitalism become anathema to young people—and why? About a year ago the Institute of Politics at Harvard released survey results showing that more than half of respondents between 18 and 29 do not support capitalism, the free-market system that underpins our economy. An astonishing one-third said they support socialism.

Clearly the tenets of capitalism are deeply and fundamentally misunderstood. No system has done a better job addressing the very issues that its critics think are important. Capitalism has stabilized...