If we look beyond the issue of monetary nonneutrality, then we do find areas of macroeconomics that use rational expectations and in which important … - Robert Barro

In contrast to Smith’s incomplete modeling, his follower, David Ricardo, provides a coherent setting— basically, the first macroeconomic model—that can be tested, modified, and applied. Although Ricardo is surely narrower and less imaginative and insightful than Smith, he is also a lot better organized. That is why Ricardo’s analysis of macroeconomics—for example, of the implications of public debt—is more coherent and useful than Smith’s.

I learned later that economic reasoning was not just mathematics and could be applied to a wide variety of social problems. Now, I think that no forms of social interaction—including religion, love, crime, and fertility choice—are immune from the power of economic reasoning. Hence, even widely held beliefs—for example, that beauty is an illegitimate credential of a worker or that democracy is important for economic growth—are not sacred truths and are subject to analysis.

The last chapter modeled technological progress as an increase in the number of types of products, N. In this chapter, we allow for improvements in the quality or productivity of each type. This approach has come to be known as the Schumpeterian approach to endogenous growth. We can think of increases in N as basic innovations that amount to dramatically new kinds of goods or methods of production. In contrast, increases in the quality of the existing products involve a continuing series of improvements and refinements of goods and techniques.