Comment by kbenson

Salved are free in neither up front nor ongoing cost, just as industrial equipment is not. It comes down to costs. Industrial equipment that is most costly than slaves seems unlikely to supplant them based on monetary incentives alone, while once it is less costly it's just the social economic momentum which needs to be overcome, which is likely a matter of time.

Importantly, I think there's only so much advancement you can get out of people by investing in economies of scale and iterating on process (and people, as icky as that idea is), while there's a huge amount of advancement to get out of machinery, including moving to whole new categories of machinery (which depending on how far you want to take the "slaved are machines" metaphor is waht a shift away from slaves was in the first place). In that respect maybe what you're noting is just that the shift from slaves to machines was the first in an iterative process which is speeding up over time.

> If we'd abolished slavery in Roman times we might have terraformed Mars by now.

I think maybe the right was to look at it is if we were able to abolish slavery and keep the same output (which might have required an economic or social system that incentivized farm consolidation for economies of scale that plantations were able to more easily achieve), then yes, we would have terraformed mars by now, but probably just because we happened to be along the tech tree earlier in the timeline.