Example of how Bohm-Bawerk either didn’t read or didn’t understand Marx: in the third volume of Capital Marx asserts that social value comes from adding the average rate of profit to the cost of production, while in the first volume he doesn’t mention this phenomena, only talking about the rate of profit. Here Bohm-Bawerk accuses Marx of contradicting himself. But there is no contradiction. We know that the elementary theory of socially necessary labor time involves the deviation of value from price and the redistribution of profit in through exchange. The same happens with the theory of prices of production.
Another small example. Marx held three equalities to be true for the economy as a whole:
1. total value equals total price
2. total surplus value equals total profit
3. total value rate of profit equals total money rate of profit
Bohm-Bawerk said that this doesn’t prove anything. But this is not meant to prove anything. They merely frame the contours of what value is. Value is not a phenomenon where every commodity is going to appear with an exact measure of its labor time. The economy is much to complex for that. Rather, price, though formed wholly of the substance of value, is always a refracted measure of value, reflecting at any moment a number of different determinations.
Another example: Bawerk tells us that it is admitted by Marx that individual commodities do not exchange for one another at their values. Stress is laid on the fact that these individual deviations compensate or cancel each other. How much of the law of value is left? The entire train of reasoning is beside the point. Marx is inquiring about the total value, and Bohm-Bawerk complains because he is not inquiring about the value of the individual commodity. But here Bohmmy fails to see what Marx is aiming at. It is important to show that the sum total of the prices of production is identical with the sum total of the values, because thereby, first of all, it is shown that the total price of production cannot be greater than the total value. But, inasmuch as the process of the production of value is effected solely within the sphere of production, this signifies that all profit originates from production and not from circulation, not from any addition to the finished product subsequently effected by the capitalist. Second, we learn that, since the total price is equal to the total value, the total profit cannot be anything else than the total surplus value. The total profit is thereby quantitatively determined, and solely on the basis of this determination does it become possible to calculate the magnitude of the rate of profit.
“tl;dr” – Bohm-Bawerk