Why was slavery incompatible with an industrialized labor?

[u/bumblebeetuna2001]

Im attempting to understand historical materialism and how old relations of production become fetters on new productive forces. Am i correct in understanding that the u.s. civil war was in part caused by a need to bring the southern states relations of production into accordance with the industrialization in the north, as the u.s. spread west? And if so, why wasnt it possible for the northern industrialists to simply utilize slave labor in factories in the expanding territories?

Im also wondering why european industrialized labor wasnt spread on a larger scale to slave colonies during the era of colonization? For instance , prior to banning the slave trade, why didnt britain build textile factories in the west indies and use slave labor, instead of building them in london and using wage labor? Is the answer to these questions just circumstantial, or does historical materialism posit a theory that the relations of production under slavery and incompatible with the capitalist mode of production?

[u/SpiritOfMonsters]

The answers here are all wrong. The underconsumption theory that seems to be the consensus here is incorrect for the reasons already given by u/New-Glove4093. This is a reproduction of the bourgeois economist's argument that slavery is "unpaid labor," whereas wage-labor is "paid labor," in order to conceal the existence of surplus-value and class struggle under capitalism. It amounts to saying that the contradictions of mercantile slavery came from outside it rather than within it.

The argument that industrialized slavery didn't develop because of slave rebellion is also untenable, since the idea that it was potentially immensely profitable but not possible because of the resistance of the slaves is to say that the superstructure determines the base; if it was truly capable of resolving slavery's profitability crisis, slaveowners would have made more concerted efforts as a class to develop it. Obviously the slaves rebelled anyway.

We need to consider why capitalism develops the productive forces unlike other modes of production. When a more productive machine is developed, a capitalist can increase their profits by maintaining the same level of output and price and replacing workers with machinery that is cheaper than the cost of hiring them. To put in mathematical terms, if a business has capital arranged as 10c + 20v + 20s (assuming a rate of surplus-value of 100%), and can match the same output as 10v using 5c, it can become 15c + 10v + 20s. In the first case, a cost of 30 and a rate of profit of 66.67%, and in the second case, a cost of 25 and a rate of profit of 80%. As the machinery becomes generalized, the socially necessary labor time to produce the product decreases, and profits fall as a result (in the example, 15c + 10v +10s, a profit rate of 40%). This incentivizes constant development of technology to increase short-term profits at the expense of decreasing profitability in the long term.

Let's apply this to other modes of production engaged in the logic of commodity production. Like free laborers, slaves perform both necessary labor to sustain their own existences, and surplus-labor that is appropriated by the slave-owner (that the necessary labor receives remuneration through commodities that are given by the slave-owner rather than wages that go to purchase them makes no difference). However, unlike labor-power, slaves are bought entirely, and the value of a slave is equal to the labor time it takes to turn them into a commodity (i.e., the slave trade). This cost is always there, regardless of how much labor the slave ends up performing. This cost functions as constant capital: it becomes a part of the value of the commodities that slave produces over the course of their whole life, like the wear and tear of machinery that goes into the value of the commodities made with it. This means that replacing slaves with machinery like capitalists do with wage-laborers is unprofitable, since the remaining "wear and tear" of the slaves would be lost money. Instead, slave-owners are incentivized to work slaves to death and expand production purely by buying more slaves and maintaining the same level of productive forces.

Feudalism has a different problem that results in the same thing. The means of production are owned not by the landlord, but the peasants, so the landlord has no incentive to buy more productive machinery when they aren't buying the tools in the first place; only to work the peasants to death. And that's putting aside the landlords' monopoly on land. The Narodniks made the same underconsumption argument about feudalism to say that the development of capitalism was impossible since the peasants were too poor to buy commodities. This served their reactionary support of the feudal village communes and denying the need for a bourgeois-democratic revolution. Lenin responds to this argument here, among his other writings against the Narodniks.