As most know, I am of the opinion that human beings are still basically, the same stupid primates driven by unvarnished primate psychology as we were 2,000,000 years ago.
(yes, it IS stupid to give monkeys guns)
Given that, I often ponder one of the few truly decent and non-primate things humanity has ever done, which is to outlaw slavery. Well, it's still practiced so it's not fully outlawed, but pretty close.
Recently, due to the large amount of thought I have been giving the environment and energy usage, in which my perspective has been altered with all the new information/data and all the new perspectives for looking at this problem (thanks to hatrack and GliderGuider, respectively), I have been beginning to think that the ONLY reason slavery was abolished, we monkeys being monkeys, was because our energy input grew to such a level that the wealthy no longer needed us to power their generators and pull their carriages.
Now that energy input is falling, and if it falls to pre-industrial, then yes, I am beginning to think that slavery will coming back in a big way within two to three centuries (perhaps much sooner), and by that I mean full 95%+ human reacceptance of it's "rightness".
In three centuries or less, the human-powered sedan-chair will be a preferred mode of travel of the Royal Bushies cutting through the smelly traffic of their unwashed Subjects.
Unless we have closer to an 18th-century level energy input, then maybe the sedan-chair won't come back. But ONLY if there is some other way for the Royal Bushies' to get around in style. If not, it's sedan-chairs.