William Baumol, one of the most famous economists you've never heard of, died recently . Baumol's fame came out of the observation that there are sectors of the economy in which productivity is rising swiftly, for example, manufacturing, and sectors where it is rising slowly or not at all, for example, string quartet performances. The conclusion he drew from observing the behavior of wages in these sectors was that wages had to rise in the low-productivity growth sectors even as they do in high-productivity growth sectors. This is because people will over time simply leave the low-productivity growth sectors for the better wages of the other sectors. This theory became known as Baumol's cost disease. In practice, society still values string quartet performances enough to pay their practitioners sufficiently to keep them playing. Baumol extended his theory to any economic sector in which personal service is essential to that sector. Examples include education, health care, c...