system
Given the following post, respond as if you're commenting on Reddit:
human
Marxism: Is there any coherent argument for the existence of value as an entity separate from price?

According to the nowadays standard interpretation of Marx, he is taken to have thought that commodities possess value - abstract labour taking on the form of exchange value. Marx, according to many, tried to prove the existence of value with the so-called third thing argument: if commodity A is worth as much as commodity B, there has to be some substance that exists in equal quantities within both. This is largely thought to be unconvincing. Are there other arguments that are regarded as more plausible?
gpt
Marx answers this directly in *Capital Vol. 1.* Value isn't price for the simple reason that whatever changes in price may occur (currency deflation/inflation, change of productivity or supply/demand of another exchanging commodity) a commodity nonetheless maintains a specific ratio of exchange according to a third principle manifest in exchanges. Value concerns this matrix of relational ratio in general, not particularly. Value therefore is not a thing in a commodity which is inherent to it, but an expressed social nexus of specific social relations and activities we call economic. Value is general, price is a particular determinate form of value abstracted as such in terms of currency.

He specifically gives the example of, say, wheat. If all else remains the same yet wheat productivity rises two fold in a market cycle, then wheat's value is cut in half and so does its price due to the cascading effect on supply/demand and competition. If the inverse productivity happens, then the inverse follows generally. If the market remains the same but currency inflates or deflates, then no value is gained or lost. If we are not dealing with money currencies, but commodity barter, if 1 bushel of wheat exchanges for 3 pounds of onions today, and for 1.5 pound of onions tomorrow while maintaining the same exchange ratio with other commodities, then wheat has not gained value, but onions gained value.

Whether you agree labor time is value is irrelevant, what is the case is that empirically and logically value and price are obviously not the same phenomenon at all. There is, of course, a difference between generative self-repeating economic cycles thay form an interdependent system of needs, and contingent one-off exchanges of things that have no general pressure or measure in the market—such exchanges are ones in which value is completely arbitrary and without much consequence.