“Now if there is a well-established fact which dominates economic life, it is the incessant, even hourly, variation in the prices of most of the important raw materials and of the wholesale prices of nearly all foodstuffs. But the reader of Mr. Keynes’ theory is left with the impression that these fluctuations of prices are entirely unmotivated and irrelevant, except towards the end of a boom, when the fact of scarcity is readmitted into the analysis, as an apparent exception, under the designation of ‘bottlenecks’. And not only are the factors which determine the relative prices of the various commodities systematically disregarded; it is even explicitly argued that, apart from the purely monetary factors which are supposed to be the sole determinants of the rate of interest, the prices of the majority of goods would be indeterminate. Although this is expressly stated only for capital assets in the special narrow sense in which Mr. Keynes uses this term, that is, for durable goods and securities, the same reasoning would apply to all factors of production. In so far as ‘assets’ in general are concerned the whole argument of the General Theory rests on the assumption that their yield only is determined by real factors (i.e. that it is determined by the given prices of their products), and that their price can be determined only by capitalising this yield at a given rate of interest determined solely by monetary factors. This argument, if it were correct, would clearly have to be extended to the prices of all factors of production the price of which is not arbitrarily fixed by monopolists, for their prices would have to be equal to the value of their contribution to the product less interest for the interval for which the factors remained invested. That is, the difference between costs and prices would not be a source of the demand for capital but would be unilaterally determined by a rate of interest which was entirely dependent on monetary influences. (Hayek 2009 : 374–375).But the crucial passage is here:
“The reason why Mr. Keynes does not draw this conclusion, and the general explanation of his peculiar attitude towards the problem of the determination of relative prices, is presumably that under the influence of the ‘real cost’ doctrine which to the present day plays such a large role in the Cambridge tradition, he assumes that the prices of all goods except the more durable ones are even in the short run determined by costs. But whatever one may think about the usefulness of a cost explanation of relative prices in equilibrium analysis, it should be clear that it is altogether useless in any discussion of problems of the short period.” (Hayek 2009 : 375, n. 3).Of course, the idea here seems to be that, in the long run, prices move towards marginal cost, so it is not modern mark-up pricing theory per se.
Nevertheless, Hayek is utterly wrong that many, even most prices, are not determined by costs of production in the short run. On the contrary, we now know, after many decades of empirical study, that most prices are cost-based or mark-up prices and are determined by total average unit costs plus a profit mark-up, not only in the long run but also in the short run. Therefore an economic theory that assumes this is how most prices are set is entirely realistic and correct, and it is marginalist pricing theory that is severely flawed and wrong.
Hayek, F. A. 2009 . The Pure Theory of Capital. Ludwig von Mises Institute, Auburn, Ala.