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History of Political Economy 32.3 (2000) 517-551
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Productive Nature and the Net Product:
Quesnay’s Economies Animal and Political
H. Spencer Banzhaf
If there is one thing that somebody is likely to know about the physiocrats, it is that they held steadfastly to a theory of the exclusive productivity of agriculture. Having special access to the productive power of Nature, agriculture alone can yield the produit net, or the net product, which is a free gift from Nature and the sole source of wealth for the economy. Ronald Meek (1962, 378) has called this the “really essential and distinctive element of the physiocratic model.” But while the most well known, this doctrine is also the most troublesome: it has been explained away, dismissed, and ridiculed; but it has not been well understood. Most, with Adam Smith, are content to label it the “capital error” of the physiocratic system ( 1937, IV.ix.638) and move on.
This article seeks to explore the essence of the net product and Nature’s role in its formation via an unlikely path: the medical writings of François Quesnay (1694–1774). Quesnay’s medical writings, which are from the early part of his career, provide insight into his paradigms and methodology, helping shed light on how he may have thought about the economy.
Section 1 of this article motivates the discussion by arguing that Nature is an inexpungible part of the physiocratic system; ignoring it [End Page 517] as some recent scholarship has done is impossible in the face of its textual support and its centrality in physiocratic thought. Nor can the role of Nature be reduced to a simplifying assumption or abstraction that adequately captures eighteenth-century French economy. Thus, a good understanding of physiocracy requires a good understanding of the role of Nature.
Section 2 begins the process of contextualization, arguing from Quesnay’s analysis of natural law that his understanding of social systems such as the economy is modeled on his understanding of physical systems. This connection suggests that his medical writings (the best record of his understanding of physical systems) may provide insights into his economics. Accordingly, section 3 provides background to medical thought in the Enlightenment, while section 4 turns to Quesnay’s medical thought in particular. Section 5 then concludes by returning to Quesnay’s political economy. The section argues that Quesnay’s critical need for a prime mover in the physical order, seen in his medical writings, carries over to the social order as well. This provides an interpretation for the net product and the role played by Nature. Specifically, Nature is the prime mover of the economy, setting it in motion, and the net product is the measure of this motion. Its immediate recipient, agriculture, is therefore uniquely productive, while other sectors only receive their motion from agriculture.
1. Nature and Physiocracy
Quesnay, accepting a basic distinction between use value and exchange value, stressed exchange value as the measure of wealth. “As the market value is, so is the revenue.… Abundance plus dearness equals opulence” ( 1962, 84;  1962, 235). In the traditional interpretation, Quesnay’s analysis of exchange value hinges on the difference between two prices, the market price (prix vénal) and the fundamental price (prix fondamental), where the latter reflects the costs of production, including the maintenance of advances, the feed for livestock, and the subsistence of labor. The difference between these two prices, a measure of surplus, is the net product, the profits for society. Quesnay equates the net product with opulence, for without it the revenue is sufficient only to cover the subsistence of workers, leaving nothing to support the proprietors, the monarch, or the church. To maximize the net product, Quesnay recommends policies that will increase the [End Page 518] market price of agricultural commodities to their “proper price” (bon prix), such as lifting prohibitions and duties on agricultural exports.
As illustrated in the tableau économique (Meek 1962; Kuczynski and Meek 1972; Pressman 1994), the net product accrues only to the productive...