Constant Capital and Value Creation

Why does constant capital (plant, machinery, raw material, etc) only transfer its value to the final commodity without creating any surplus value? I think I understand the tendency of the rate of profit to fall fairly well now, but I'm still struggling with this bit.

Machines are just ingredients factored into the cost of production while labor is the social substance all value is made of as all commoditys are composed of labor and nature. Surplus value is only created by unpaid labor while machines as crystalized labor and allready finished laboring.

It's an axiomatic thing, only human labour power can imbue value. Say you have a magic machine that churns out widgets for ten years before breaking down without having to be worked. Now also assume you use that to feed into a different machine. What will be the cost of a widget, for calculating the input cost of the second machine (to avoid autistic screeching about markets and competition for a sec)?
It's exactly the cost of raw inputs plus a pro rata of the cost of the machine. A surplus (exchange) value can't enter anywhere no matter the use value of the widget, because it can be produced at cost and only at cost. A machine cannot be squeezed like a man can for extra labour time, for extra intensity, above it's input cost. You cannot underpay a machine.

Because they wear out while operating while humans regenerate for free.

Constant capital can only provide a constant value equivalent to what is spent of it in creating the commodity, if this was not the case then you would be able to create a machine that generates a profit on its own, which is empirically impossible.

I mean, yes, machines need maintenance, but I don't think it's proper to just consider machines simply as warehouse capacity for maintenance hours or whatever. Repairing a broken machine into a working one is almost surely going to take less materials/effort than creating a new one from scratch; there's scenarios in human society where this isn't the case, but I'm pretty sure they basically all have to do with bureaucratic inertia and other parts of capitalism rather than anything to do with repair being objectively harder than replacement.

Besides, giving machinery a role of "constant capital" means it's much easier to describe in the same language as one would use ideas, sunlight, and other "permanent" resources, which I think is useful.

They're not. Constant capital represents the aggregated value of the machinery and raw resources used in the commodity production. Their value is fixed because they are finished commodities by themselves and cannot add more value than what they are worth.

At the end of the day the machines used are themselves built by a sum of constant capital and variable capital, which can be broken down again and again all the way to the natural resources extracted that acquire the value the worker extracting them imprints them with.
And you're simply restoring their value, not adding more.

Oh, okay, I get what you're saying here; while humanity can and has made themselves better producers, utility is not value; when a seller charges a buyer X dollars for labor + Y dollars for the privilege of using a particular machine, that Y dollars is actually both rent the seller is extracting from some abstract mixture of his workers and you (consumer exploitation does exist; see monopolies, artificial scarcity, why companies advertise, etc.) and payment for rent the seller previously paid in the creation of that machine. Thanks, that clears that up.

That said, I still don't quite buy the LTV; there are consumable resources in the world that aren't strictly/linearly convertable to labor hours (machine time, tons of various metals, barrels of oil, kilowatt hours of electricity, acres of land, etc.) and sellers can extract rent from their use of these resources just as easily as they can hours of labor.

lifetime of machine/average labour time spent creating the machine (including all accumulated dead labour)
average labour time spent mining and transporting, the exchange value expressed in money does depend on supply/demand, Marx is clear about this
enclosure of the commons doesn't generate value, only capital

You have to break them down. The metals extracted acquire value only in the moment they are extracted by a miner, the same for the barrels of oil and electricity. Land is a bit more complicated, I would need to refer to Marx theory of rent, which I am still not too well versed in, but it's still easily explainable by the LTV.

Labor might be convertable into those resources in the long term (even then, though, there's issues; there's only so many acres of fertile earth on the surface or tons of metal in the crust, and if you spend so much labor and metal to enhance widget thoroughput you won't be able to use that labor and metal to enhance foobar thoroughput), but in the short term, you only have so much machine thoroughput and so many tons of metal, and you have to ration those in the most effective way. Under capitalism, this is done by making certain individuals or groups "owners" of those resources, allowing those owners to sell what they create and buy the money obtained how they wish; this is done ostensibly to create prices for each good which allows producers to know how much each is desired and retune production to meet that demand. Now, this solution has a massive amount of problems, but the fact of the matter is that there are still plenty of resources besides mere hours of labor that are important in determining the value of a given product.

Value is human labour. Constant capital does not produce human labour. Only labour power does.

But why?

Why what?

"Value" means "things that had to be given up for this", right? Why, then, is labor considered to be the only ingredient of "valuable" goods?

No. "Value" means: "the commensurable aspect of exchanged products".

Couldn't some rich fuck owning a very expensive machine that doesn't require any labor and competitors can't afford use that advantage and opportunity to turn a profit without the need for labor, by selling the produced commodity at the price of raw materials + machine maintenance + bit he puts directly into his own pocket?

You have to think of this on a macro level. If your hypothetical capitalist is exchanging something for more than its worth then that just means someone else is paying more than its worth. There isn't actually any value being created in the exchange just profit for the capitalist. Value can't be created through exchange only labour produces value.

The question then becomes how can capitalists (as a class not individuals) consistently create profits through exchange when value can't be created through exhange? The answer is that workers are systematically paid a wage lower than the value they create. The systemic underpayment of workers allows capitalist to skim off the value from their surplus labour which is how profit is generated.

Now you are getting outside what the LTV is: a law of value. The reasoning of Marx (and the first demonstration of the law if you want) is that commodities have only one parameter in common with each other: abstract labour. Physical characteristics of commodities are not sufficient to justify their value and neither does scarcity on its own (see diamonds for example). Abstract labour is the only variable that can be found in all commodities (and services), so it must be the determinant creator of value.

You are skipping a couple of steps here. The LTV divides value in 3 categories plus one:

-value: is the amount of labour time required to complete a commodity. This includes constant capital( aggregated value of machines and raw resources), variable capital (human labour) and surplus value (the part of value created by labour that is not counterbalanced by the wage of the worker)
-use value: is the need-satisfying power of the commodity.
-exchange value: is the value of the commodity once use value and supply/demand have been taken into account
-price: is the exchange value represented by a specific currency.

You are jumping directly to step 3, while we were talking of step 1. Scarcity is not the way value is calculated, but one of the factors. Supply and demand do make exchange values fluctuate, but they fluctuate around their base value. The "regulating mechanism" of the market is nothing more than examining how much of one commodity was sold and how much was not. Those that were unsold signal that a certain industry is wasting socially necessary labour time, if there is unfulfilled demand then it means there is less than needed labour time invested in that industry.

You got things the wrong way around. The market as a system to determine prices is inherently a reactive machine not an active one, only once the game has been played it is able to adjust prices and production. The market is not determining value, but merely reading that value a posteriori.

please mention these characteristics common enough that can be used to determine value of any commodity.

Let's put it like this: if machines could create value there would be no need to hire workers. The capitalist could buy a factory and produce money by simply owning it. This however would bring the capitalist economy to collapse as there is no public able to pay for those commodities. Value would be meaningless as it cannot be fulfilled. A machine that creates value is the fabricator of Star Trek and can exist only in a similar scenario of post scarcity. Even if we imagine a world where everyone possesses a factory the scenario would still collapse on itself as exchange of commodities would simply stop once everyone has enough machines to satisfy their needs, effectively ending any kind of market based economy and entering again what would be a post scarcity world.

What you are talking about however, when factoring in those machines as efficiency multipliers and not value generators, is a common scenario: if you are able to produce a certain commodity more efficiently than the competition, the value of the commodity falls down because you are spending less labour time creating it. You are then able to sell it at a lower price, beating the competition. The extra cash that you are bringing in is the surplus value that the competition was not able to realize in the market because they are now producing commodities at a higher value compared to society's average.

That's a monopoly, the profit here comes from the power you gain in the post production marketplace of exchange, not from the production process.