I've read a lot of SF with post-scarcity futures and thought a lot about what approximations to post-scarcity might be available within the real constraints of

I've read a lot of SF with post-scarcity futures and thought a lot about what approximations to post-scarcity might be available within the real constraints of physics and engineering. I've yet to see a plausible solution to the problem of violence. In the excellent Culture novels of Iain M. Banks, it was safe to have self-replicating machines and titanic energy sources all over the place, because omniscient and omni-benevolent AI watched over everything. The Minds could prevent violence far faster than biological intelligence could initiate it. Strong, friendly AI and physically impossible Space Opera Science are required to prevent violence this way. Authors Marshall Brain and Alastair Reynolds (in Manna and the Poseidon's Children trilogy) were more respectful of physics but creepier when they posited that you could use machine surveillance plus controls wired directly into the human central nervous system to interrupt violent actions. Even discounting the creepy-factor, even assuming the biomedical engineering is possible, it's hard to see how you reach 100% global participation in a scheme like that. No doubt crime rates will decline if everyone grows up in a safe, stable environment and never faces hunger or other serious unmet needs as adults. But there are other outbursts of violence that have nothing to do with poverty. Someone who leaves the UK to join ISIS in Syria isn't doing it because they are hungry. Someone who shoots their ex-spouse and a bunch of the ex-spouse's coworkers isn't doing it because they want better clothing. Universal prosperity isn't going to completely eliminate irrational violence. It's going to be interesting times indeed if someone with an unhinged grudge can fab up a jug of nerve gas just as easily as Americans today can buy firearms.