‘Hierarchy of Causes’ and Theory of Money in Ricardo and Keynes

In a paper published in the December 2014 issue of Journal of the History of Economic Thought, Maria Cristina Marcuzzo concludes that "notwithstanding these profound epistemological differences, Ricardo's quest for a theory in which the hierarchy of causes is detectable in the structure of the arguments was also pursued by Keynes, who shared with Ricardo the recognition of its relevance and usefulness." This suggestion that Ricardo and Keynes – two authors with whom Marcuzzo shared a lifelong intellectual companionship – might be bedfellows on methodological issues is all the more surprising since it relies on a distinction made by Ricardo between "permanent" and "temporary" causes, which Marcuzzo illustrates with the notion of "natural quantity of money" – that is, a notion which could hardly be found in Keynes's General Theory. This divergence on the conception of money is one of the "profound epistemological differences" acknowledged by Marcuzzo, but in her view it does not preclude a common quest by both authors for a "hierarchy of causes." It may then be worthwhile inquiring whether Ricardo's and Keynes's respective theories of money are consistent with such common methodological approach. The conclusion of the paper is that a "hierarchy of causes" may be detected in both monetary theories under one condition: the existence of an institutional datum (the legal price of gold in Ricardo, the central-bank rate of interest in Keynes) which regulates the quantity of money.