Various forms of slavery were nearly universal before the industrial revolution. After industrialization, it would naively seem forced labor would continue to be widespread, as there is no way to compete against it. But it only remained or became entrenched in a few locations and market sectors. Even current non-industrialized economies rarely involve slavery. I can't find a convincing explanation of why.
I find it impossible to believe it was because of lofty values for human rights. But imagining US/English history without a labor movement, for example, seems like it was resulting in the kind of sweathouse economy I would have expected to be typical. It is hard to believe labor movements have really been effective enough to have so dramatically shifted the equilibrium world-wide for a century. Am I wrong?
I also find it impossible to believe that most work requires education incompatible with being indentured, or that maintaining discipline and motivation would be prohibitive. Do the data say otherwise?
Maybe workers create so much more profit when they are themselves maximal consumers that capital creates political pressure to inflate wages above subsistence, to create (investment) markets? I think this would be capitalists' explanation, but coordination among capital would be susceptible to being undercut, prisoner's-dilemma style, by competitors willing to use slaves. I think the only thing that prevents that in an international context are trade agreements, but again, it is hard to believe those have been so dramatically effective.
I haven't been able to find this question addressed with data, it is always completely overwhelmed with ideology.
Here's the best answer I see on this site, but they claim slaves cost more to feed than they produce (under most circumstances). That can't be right -- workers make enough to eat, profit their employers, and buy comforts unavailable to slaves (including time off, medical care, and retirement), considering redistribution of course. So why hasn't capital driven those comforts to zero?
I asked on economics stack exchange, and this answer contained an insight I find plausible: you can fire/exchange a wage worker, but you can't sell an unproductive slave. So capital is willing to pay to insure against sinking costs into future labor of uncertain value. Do data support this idea?
The kind of studies I'm looking for that I think would be most convincing:
- Cases where capital invested in slaves was lost when their labor depreciated due to some market shock.
- Higher profits in wage vs slave economies that were otherwise similar.
- Cases where wage workers utilized more of their capacity (were more productive) than slaves doing similar work.
- Cases of capital lobbying against slavery/for higher wages in order to create customers.
- Attempts to lower wages or coerce labor that failed for some reason, like unionization, violent revolt, etc.
- Observation among otherwise similar economies of correlation between slavery index and social stability/unrest, growth/development, longevity, robustness to shocks, labor productivity, capital investment, etc.