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History of Political Economy Annual Supplement to Volume 33 (2001) 235-251
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Making Measuring Instruments
Mary S. Morgan
In the mid-nineteenth century, economists had many numbers but relatively few measurements; by the mid-twentieth century, they began to take for granted that they had measurements for most of the phenomena about which they theorized. This is the change that marks the impact of the age of measurement, and my interest in this prespective essay is to provide an understanding of what this change entailed. Out of many different economists' individual practical measuring projects around the late nineteenth and early twentieth centuries, there emerged a number of different kinds of measuring instruments, each carefully fashioned for economics. By looking carefully at the materials collected in this volume, we can discern that these instruments can be grouped according to the strategies or recipes that were followed in making such measuring instruments. As a historical development, first the instruments, then the strategies, served to connect the ambitions of economists seeking accurate scientific measures of their world with the practically necessary, sometimes mundane, but never trivial tasks of data collection. [End Page 235] Both measuring instruments and measurement strategies are a consequence of the age of measurement, not a prerequisite for it.
Making measurements of economic entities requires instruments of a certain kind. The second broad historical thesis suggested by the essays in this volume is that the measuring instruments that economists built in this period were also analytical devices. These instruments embodied frameworks and techniques to turn observations into measurements and to organize the empirical data into particular types of arrangements so that economic phenomena might be arrayed before us. On one view, we can see this as a historical process of establishing facts about phenomena, paralleling the epistemological interests of Bogen and Woodward (1988).1 On another view, this process can be seen, ultimately, as one of creating new categories of phenomena, paralleling the historical interests of Theodore Porter ( 1996). I begin in the former tradition and will return to the latter interpretation.
It is a conventional, and surely uncontested, claim that taking measurements requires instruments of measurement. From our childhood use of fingers and rulers to the technicalities of clocks and Geiger counters, we rely on tools to help us measure our world. Economics is no different, except perhaps in being relatively slow to develop such measuring instruments. The discipline did not develop such devices until the late nineteenth and early twentieth centuries, whereas there had been a dramatic increase in the number and range of measuring devices in the natural sciences in the seventeenth and eighteenth centuries (Heilbron 1990).
Economists of the late nineteenth century wanted to measure all sorts of things, from the close-up single choice of an individual to the aggregate price level changes in the economy as a whole. But they had few instruments that would allow them to do these things. Whereas some might suppose that economic measurement is merely counting “what is there,” a similarly naive view would have us think that x-ray machines merely look through our flesh to reveal our bones. We don't see a macroeconomy, nor a consumer price index, nor an individual choice decision, hence fashioning measuring instruments in economics has been, in part, [End Page 236] a matter of developing ways of observing the economy. It is consistent with this to note, from the history of science, that the design and use of measuring instruments are often aligned to experimental investigations.2 Our analogy continues with the advanced medical scanners, instruments of investigation that are designed and programmed to enable us to “see” certain things inside us by picking them out in a particular way. The ways in which the economic body is investigated and data are collected, categorized, analyzed, reduced, and reassembled amount to a set of experimental interventions—not in the economic process itself, but rather in the information collected from that process. Economic observations must not only be registered but also converted into measurements, and converted in ways which serve...