Marx's concept of "exploitation" and the problem of measurement

The paper scrutinizes Marx's proposal to measure the "degree of exploitation" in terms of the "rate of surplus value". This amounts to defining an equivalent to the device of the thermometer in measuring temperature. The condition to be met is that a concept must be suggested that allows one to express the degree of exploitation in an independent manner and to show that the two move in parallel with one another. It is then shown that the rate of surplus value does not satisfy the sought criterion, because it may move in opposite direction of the degree of exploitation. This is demonstrated in terms of a simple numerical example with a choice of technique concerning the lengthening of the working day.& COPY; 2023 Elsevier B.V. All rights reserved.