Index: p. 411-426.

In 1980, the twenty-four-year-old graduate student Paul Romer tackled one of the oldest puzzles in economics. Eight years later he solved it and published a paper that became the flashpoint of a decade-long debate among growth economists. In Knowledge and the Wealth of Nations, economic journalist David Warsh uses Romer's paper as the central redoubt from which to view modern economics and one of the discipline's oldest riddles. The paradox of falling costs, first identified by Adam Smith more than two hundred years ago, came to haunt economics throughout the nineteenth and twentieth centuries—because, while the problem was apparent, the tools to solve it were not. Warsh skillfully narrates this story of scientific discovery while drawing astute portraits of the econ­omists involved, including towering figures such as Adam Smith, Alfred Marshall, and John Maynard Keynes as well as a new wave of theorists that includes Robert Solow, Kenneth Arrow, Robert Lucas, and Romer. In a fluid style, Warsh re-creates the series of discussions among economists that began as early as 1979 and follows them to the publication of Romer's paper and beyond, chronicling the heady swarm of new ideas and the internecine battles as Romer's fellow economists struggled with them.