Labour Values and Production Prices in Joint Production

In this article, we show that in joint production, both labour values and production prices are positive but not unambiguously determined. Usually, the former is determined under the implicit presupposition that labour productivity in the production of each commodity is the same in all production processes that produce this commodity, and the latter is determined under the indirect presupposition that the capital productivity in the production of each commodity is the same in all production processes, with the consequence that this also applies to the maximum profit rate. This presupposition is equivalent to a transformation of joint into single production—not in the ‘space’ of material quantities but in that of corresponding nominal quantities in terms of labour values or production prices, respectively. The same presupposition is not only arbitrary but also, in the case of separable technique, contradicts the technical data of the given production technique. The same applies to the above transformation of joint into simple production, which is made possible under this presupposition. Consequently, either no theory of joint production based on nominal quantities is possible, or, when it is possible, it is based on an arbitrary and, in some cases, contradictory presupposition. JEL Codes: B50, B51, B59