Nicolae Georgescu-Roegen, 1906-1994
Perfect reversibility is present everywhere. It constitutes the main pillar of the theory of market equilibrium. According to the ultra-familiar picture, if demand shifts from D to D’, the market moves from E to E’; and should, later, the factor responsible for the shift disappear, the market would return to E, in a manner perfectly similar to that of a mechanical pendulum which can swing back and forth with equal ease. True, no economist has even suggested that a process of production may be reversed so as to convert pieces of furniture back into trees. However, the classical theory of business cycles-as this traditional name indicates-rests on the idea that the entire economic process may come back to any previous position by following the same path in reverse. We should also note that the entire theory of production is still based on the simple formula known as the production function, which…is not a satisfactory description even of the reproducible process of production, i.e., of the simplest possible arrangement. But the most pertinent examples of the shortcomings of the mechanico-descriptive approach are the standard dynamic models beginning with that of Harrod and Domar and ending with those of Solow and Leontief…
[A]nother stumbling block (the most important of all) in the dynamic representation of growth…is the fact that decumulation is not accumulation in reverse If the object in point is a stock of readily consumable materials, decumulation may proceed at any rate we may choose. Conceivably, any stock may be decumulated (i.e., consumed) almost instantaneously or at a zero rate, for example. The pace of decumulation of equipment, however, is rigidly determined by the nature of the equipment. To give a homely example, the only way to decumulate a pair of boots is to use them until they are completely worn out-a process which normally requires more time than the production of the boots from leather and other materials. Accumulation may constitute the greatest worry for a planner in an underdeveloped country, but decumulation of durable goods is in fact a far more refractory issue in practice and, perforce, in analysis. (emph. added)
Through decumulation we aim to turn back past history, to reverse past actions, which is an impossible feat. But, again, because of the mechanistic epistemology of standard economics, the models which constitute the pride of economic dynamics ignore the difference between ‘forward’ and ‘backward’-the most visible symptom of the irreversibility of Change.
(NGR, “Dynamic Models and Economic Growth”, 1975)