The Macroeconomics of the Great Depression: A Comparative Approach

Article excerpt

To understand the great depression is the Holy Grail of macroeconomics. Not only did the Depression give birth to macroeconomics as a distinct field of study, but also-to an extent that is not always fully appreciated - the experience of the 1930s continues to influence macroeconomists' beliefs, policy recommendations, and research agendas. And, practicalities aside, finding an explanation for the worldwide economic collapse of the 1930s remains a fascinating intellectual challenge.

We do not yet have our hands on the Grail by any means, but during the past fifteen years or so substantial progress toward the goal of understanding the Depression has been made. This progress has a number of sources, including improvements in our theoretical framework and painstaking historical analysis. To my mind, however, the most significant recent development has been a change in the focus of Depression research, from a traditional emphasis on events in the United States to a more comparative approach that examines the experiences of many countries simultaneously. This broadening of focus is important for two reasons: First, though in the end we may agree with Romer (1993) that shocks to the domestic U.S. economy were a primary cause of both the American and world depressions, no account of the Great Depression would be complete without an explanation of the worldwide nature of the event, and of the channels through which deflationary forces spread among countries. Second, by effectively expanding the data set from one observation to twenty, thirty, or more, the shift to a comparative perspective substantially improves our ability to identify - in the strict econometric sense - the forces responsible for the world depression. Because of its potential to bring the profession toward agreement on the causes of the Depression - and perhaps, in consequence, to greater consensus on the central issues of contemporary macroeconomics - I consider the improved identification provided by comparative analysis to be a particularly important benefit of that approach.

In this lecture I provide a selective survey of our current understanding of the Great Depression, with emphasis on insights drawn from comparative research (by both myself and others). For reasons of space, and because I am a macroeconomist rather than a historian, my focus will be on broad economic issues rather than historical details. For readers wishing to delve into those details, Eichengreen (1992) provides a recent, authoritative treatment of the monetary and economic history of the interwar period. I have drawn heavily on Eichengreen's book (and his earlier work) in preparing this lecture, particularly in section I below.

To review the state of knowledge about the Depression, it is convenient to make the textbook distinction between factors affecting aggregate demand and those affecting aggregate supply. I argue in section I that the factors that depressed aggregate demand around the world in the 1930s are now well understood, at least in broad terms. In particular, the evidence that monetary shocks played a major role in the Great Contraction, and that these shocks were transmitted around the world primarily through the workings of the gold standard, is quite compelling.

Of course, the conclusion that monetary shocks were an important source of the Depression raises a central question in macroeconomics, which is why nominal shocks should have real effects. Section 2 of this lecture discusses what we know about the impacts of falling money supplies and price levels on interwar economies. I consider two principal channels of effect: (1) deflation-induced financial crisis and (2) increases in real wages above market-clearing levels, brought about by the incomplete adjustment of nominal wages to price changes. Empirical evidence drawn from a range of countries seems to provide support for both of these mechanisms. However, it seems that, of the two channels, slow nominal-wage adjustment (in the face of massive unemployment) is especially difficult to reconcile with the postulate of economic rationality. …