Why? This is highly non-obvious. To reach our current technological level, we had to use a lot of non-renewable resources. There's still a lot of coal and oil left, but the remaining coal and oil is harder to reach and much more technologically difficult to reliably use. That trend will only continue. It isn't obvious that if something set the tech level back to say 1600 that we'd have the resources to return to our current technology level.
It's been discussed repeatedly here on Less Wrong, and in many other places. The weight of expert opinion is on recovery, and I think the evidence is strong. Most resources are more accessible in ruined cities than they were in the ground, and more expensive fossil fuels can be substituted for by biomass, hydropower, efficiency, and so forth. It looks like there was a lot of slack in human development, e.g. animal and plant breeding is still delivering good returns after many centuries, humans have been adapting to civilization over the last thousands of y...
Why does SI/LW focus so much on AI-FOOM disaster, with apparently much less concern for things like
Why, for example, is lukeprog's strategy sequence titled "AI Risk and Opportunity", instead of "The Singularity, Risks and Opportunities"? Doesn't it seem strange to assume that both the risks and opportunities must be AI related, before the analysis even begins? Given our current state of knowledge, I don't see how we can make such conclusions with any confidence even after a thorough analysis.
SI/LW sometimes gives the impression of being a doomsday cult, and it would help if we didn't concentrate so much on a particular doomsday scenario. (Are there any doomsday cults that say "doom is probably coming, we're not sure how but here are some likely possibilities"?)