An Annotation in One of Sraffa,s Books
The term photograph is probably first mentioned in the context of Sraffa’s critical scrutiny of marginalist, or demand and supply, theory, with the focus on market equilibrium.
In 1904, Henry Cunynghame had published A Geometrical Political Economy, Being an Elementary Treatise on the Method of Explaining Some of the Theories of Pure Economic Science by Means of Diagrams. The book is in Sraffa’s library (item 2243) and is annotated by him. There is reason to presume that Sraffa read it at an early time. In his treatise, Cunynghame stresses right at the beginning, “All the curves mentioned in this book are intended to be applicable to states of equilibrium, reached after temporary oscillations have ceased; or rather, since all things are in a state of perpetual flux, as instantaneous photographs taken at times when the market conditions are normal’ (1904, 3; second emphasis added).In the margin of this passage, Sraffa put a straight line. By straight lines, he typically signaled the relevance of a passage from the point of view of his own studies at the time or approval of the proposition contained in it. The important thing to note here is that the photograph under consideration has been taken at the right moment, that is, when the economic system is in a “state of equilibrium” or, somewhat less stringent, when “market conditions are normal.” As anyone who has ever used a camera to catch a moment or a particular situation knows, the art consists in pushing the trigger button at the “right moment.” Missing it gives a picture that does not catch in full what the photographer was interested in seeing and in the extreme nothing of interest at all. Obviously, “hitting the moment” presupposes that the photographer already has an idea of the object to be caught and seeks to catch it when it materializes. Cunynghame’s wording makes it very clear that the trigger button of the camera must not be pressed arbitrarily, that is, at any time, but precisely when equilibrium or normal market conditions obtain.
Since they will hardly ever be realized in actual fact, it should also be clear that the photograph cannot be taken to capture the realized state of markets in an actual economy but refers to an idealized state, one that is hypothetically in equilibrium or exhibits normal market conditions. In Marshallian partial equilibrium theory, the point of reference is the intersection between a demand and a supply function, as Cunynghame stresses. The photograph thus conveys the image the photographer has in his mind of a very particular situation in the market. It does not portray reality as it is, but as the photographer thinks it is, focusing attention on the magnitudes in terms of which certain phenomena (relative prices and income distribution) can be explained.Cunynghame (1904, 3) then asks whether there is a difference between a Marshallian short and a long-period analysis and opines, “It does not seems to me, nor do I understand Professor Marshall to say (see Principles of Economics, bk. 5, chap. 4, p. 416, 1890 ed.), that there is any fundamental difference between short-period and long-period curves.” Interestingly, there is also a straight line along this passage in Sraffa’s copy of the book. What did Sraffa wish to express by annotating the passage in this way at the time when he annotated it? We cannot know for sure, but will put forward some considerations that might perhaps contain a clue to grasping what he probably had in mind. However, we will postpone this discussion and first turn to documents from Sraffa’s unpublished papers.
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