My thesis in this lecture is that macroeconomics in this original sense has succeeded: Its central problem of depression-prevention has been solved, for all practical purposes, and has in fact been solved for many decades.
The "many decades" to which Robert E. Lucas, Jr. refers in the above excerpt were the decades called "the golden age of postwar capitalism" and the decades called "the great moderation". Those many decades were the comfortable parts of the Kondratieff cycle, which is sometimes called the long wave.
A long-term view of the interest rate on 10-year Treasuries, and a long-term view of Debt-per-Dollar:
|Graph #1: 110 Years of Interest Rates (EconomPic)|
|Graph #2: Debt per Dollar, 1916-2010|
Both graphs display cyclic patterns. Each graph peaks twice, though the peaks occur at different times. The interest rate peaks earlier. DPD peaks later.
Since interest rates peaked and began falling in the 1980s, we should have known what was in store for us regarding debt. Since the 1960s we should have known. Heck, our grandfathers should have told us as much. But the people who study such things for a living (like Robert Lucas) were claiming victory over the forces of nature.