I thought I’d give my thoughts on question 1. But there are a lot of big brained people here who can give a better and more thorough answer. I’d like to here from others too!

For question 2, I’d also like to know this, so I’m looking forward to what others have to say. I know that many interpretations of the first chapters regarding the description of commodities and the money-from explain it has a ‘historical-evolution’, but I’ve also heard that the development of these ideas is not meant to be taken as a diachronic description, but instead as the unfolding of a dialectic thought-process. I don’t know enough to speak on this, so I’d like to hear more on this. This latter point was argued by Andrea Ricci in her paper The Specter of Value: The Beginning of Marx’s Capital and Hegel’s Logic of Being, but I’ve only given it a cursory reading. That may be a place to look if you can find a copy of it?

Here are my thoughts on question 1:

On pg 127-128 of the Penguin edition Marx states that the exchange values of commodities - the fact that commodities can be exchanged with all sorts of other commodities, expresses something equal between the commodities - between all exchangeable commodities. And this exchange value is a mode of expression or ‘form of appearance’ of some underlying content distinguishable from the commodity itself and its use-value. Two commodities, such as corn and iron can be exchanged, and their exchange value signifies a common element of magnitude exists between them, a common third thing.

It follows that … the valid exchange-values of a … commodity express something equal, and … exchange-value cannot be anything other than the mode of expression … of a content distinguishable form it.

For instance 1 quarter of corn = x cwt of iron. What does this equation signify? It signifies that a common element of identical magnitude exists in two different things… Both are therefore equal to a third thing, which in itself is neither the one nor the other.

And you can make this argument for any set of two exchangeable commodities, there must be some “third thing”. So the first clue here is that there is some element that is common to all commodities that explains these exchange ratios that can be made for all commodities.

The second clue is in the next couple of paragraphs where Marx states that this common element can’t be a property of the commodity’s use-value. Why? Because “the exchange relation of commodities is characterized precisely by its abstraction from their use-values.” One use-value is worth just as much as another in some appropriate quantity. In exchange, the use-values don’t matter.

When commodities are in the relation of exchange, their exchange-value manifests itself as something totally independent of their use-value.

(Though it is useful to keep in mind that with no use-value, there would be no social demand for products and hence the private labor put into a useless product would never be made/realized as social labor, never realized as value. So no use-value also means no value)

So clue 1 and clue 2 together mean there must be something that all commodities have in common which is also independent on their “geometrical, physical, chemical, or other natural property”, i.e. independent of their material use-value.

The only “third thing” between any pair of exchanged commodities that can be abstracted from use-value is human labor in the abstract.

If we disregard the use-value of commodities, only one property remains, that of being products of labor.

With the disappearance of the useful character of the products of labor, the useful character of the kings of labor embodied in them also disappears… They can no longer be distinguished, but are all together reduced to the same kind of labor, human labor in the abstract.

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It’s also important to note that value, and these exchange ratios, emerge independently of the will and foreknowledge of the exchangers. It isn’t that people know that they

“bring the products of their labor into relation with each other as values because they see these objects merely as … homogenous human labor. The reverse it true: by equation their different products to each other in exchange as values, they equate their different kinds of labor as human labor. They do this without being aware of it” (pg. 167)

And an important part about labor being the origin of value, and this is also important for the law of value is that these exchange ratios, value, signifies the quantitative proportions of the social division of labor. Within an economy there is a “homogenous mass of human labor-power” (pg 129) and to reproduce the use-values of this economy, given some levels of productivity for each branch of industry, this “homogenous mass” must be redistributed into distinct branches. A social division of labor must occur across the branches so the “correct proportion” of labor-time is applied to each branch to adequately reproduce our society (our use-values and ourselves). This necessary proportion of labor-time into each branch is the socially necessary labor-time, and it is what is ‘underneath’ value, in my interpretation.

… all the different kinds of private labor … are continually being reduced to the quantitative proportions in which society requires them. The reason for this reduction is that in the midst of accidental and ever-fluctuating exchange relations between the products, the labor-time socially necessary to produce them asserts itself as a regulative law of nature … The determination of the magnitude of value by labor-time is therefore a secret hidden under the apparent movements in the relative values of commodities. (pg. 168).

My take is that value, being social, is a product of our own species’ limited social labor-time. There are only so many working hours possible in a day, and in order to recreate our society these limited labor-hours must be divvied up into concrete proportions across various “branches” (types of concrete labor). And unlike any other commodity or product, such as oil, electricity, grain, etc., all products of labor (all commodities) have their ultimate source in labor, hence in a definite division of social labor. So all commodities, and the facts of their production, their supply, the quantities in which they exchange with each other, etc. can be traced down to the labor-time that our society spends on creating them. No other element is the “common element” to all commodities.

There have also been some empirical studies to investigate this. Cockshott comes to mind (though if you ever look into him be warned he is a transphobe), as well as Zachariah and Petrovic. There have been some studies that investigate the correlation between production prices vs labor values vs the prices of other “potential value sources” such as oil, electricity, etc. These suggest that the empirical evidence also supports the labor theory of value - though I don’t recall much of their methodology. I’d have to go back and reread them more thoroughly!

• Petrovic - The Deviation of Production Prices from Labor Values: Some Methodology and Empirical Evidence (1987)

• Zacharia - Testing the labor theory of value in Sweden (2004)