I've seen out there expert analyses on raw destruction and on factors like subsequent global climate devastation showing this conclusion from any plausible military contigencies and actions.

The only one I've personally read is Herman Kahn's On Thermonuclear War, which oversimplifies a lot and generally tries to paint matters as optimistically as possible; as well, people from that era like Samuel Cohen in his memoirs describe Kahn as willing to fudge numbers to make their scenarios look better.

Personally, I am not optimistic. Remember the formulation of existential risk: not just extinction, but also the permanent curtailment of human potential. So if industrialized civilization collapsed permanently, that would be a serious x-risk almost up there with extinction itself. I agree that I don't think nuclear war is likely to immediately cause human extinction, but if it destroys industrialized civilization, then it's setting us up to actually be wiped out over the coming millennia or millions of years by a fluke pandemic or asteroid or any of the usual natural x-risks.

Coal, oil, surface metals, and many other resources are effectively impossible to extract with low-tech levels like say the 1800s. (Imagine trying to frack or deepsea mine or extract tar with 1800s metallurgy or anything.) Historically, we see that entire continents can go for millennia on end with little meaningful change economically; much of Africa might as well not be in the same world, for all the good progress has done it. Intellectual traditions and scholarship can become corrupted into meaningless repetition of sacred literature (how much genuine innovation took place in China from AD 0 to AD 1800, compared to its wealth and large intelligentsia? why do all acupuncture trials 'succeed' in China and Japan when it's shown to be worthless placebo in Western trials?) We still don't know why the Industrial & Scientific Revolutions took place in Western Europe starting around the 1500s, when there had been urbanized civilizations for millennia and China in every way looked better, so how could we be confident that if humanity were reduced to the Dark Ages we'd quickly recover? Brief reparable interruptions in globalized supply chains cause long-lasting - we still haven't recovered to the trendline of hard drive prices from the Thai floods, and that was just flooding, nothing remotely like a countervalue nuke against Bangkok knocking out a good chunk of Thai business & financial infrastructure. Experience/learning curve effects mean that high efficiencies are locked up in the heads and hands and physical arrangement of existing capital, so plants cannot simply be replaced overnight, the expertise has to be developed from scratch. Complex civilizations can simply collapse and disperse back into the low-tech agrarian societies from whence they sprung (I'm thinking particularly of the case-studies in Tainter's Collapse).

Of course, we can't yet name an industrialized civilization that collapsed, but it's not like it's been a thing all that long - the Roman Empire lasted a lot longer than the Industrial Revolution has, but nevertheless, we know how that ended.

I have to say that nuclear warfare was less of a human extinction risk than some people tend to think or is directly suggested by this text. Even a straight all out war between the United States and Soviet Union using their full arsenals would not have caused human extinction nor likely have prevented some technological societies from rebuilding if they didn't outright survive. I've seen out there expert analyses on raw destruction and on factors like subsequent global climate devastation showing this conclusion from any plausible military contigencies and actions. The remaining arguments in favor would have to be pretty convoluted, like by setting a sociopolitical precedent it would automatically guarantee any future or rebuilt societies would seek military conflict through further nuclear wars.

The most dangerous extinction risk that could be caused by human action in the 20th century probably would have been deliberate attempts at destruction of the ozone layer in a supervillain sense. (This could be facilitated by nuclear weaponry, of course.) No actual polity as far as anyone knows, I think, planned such a thing. Accidental destruction, timed differently in an alternate history pathway, could also have been pretty bad. To consider and compare a full range of hypotheses, biological warfare was (and still is) a threat but overall is probably less of an x-risk as well, if you understand the flat out mass extinction potential of ozone destruction.

It wouldn't be bad to invite debate on these points as I think actually fully understanding various x-risks, near misses in the real world, and all that is rather important to getting something useful out of this parable.

Been a lurker for a relatively short time, took the survey.

I had some concerns over the extra credit questions and one thing in particular that prompted me to respond. I agree it seems there was meant to be no right answer to a couple of the questions, and the babies in the hospital was at least a clear statistical problem. I also had an admittedly whimsical objection to the lack of details on one question, thanks to the level of specificity seen in riddles, puzzles, and so on here, and maybe due to a programmer background thinking of pointers and assignments. The first CFAR question should have specified to start something like there are three people in a room. Then it's clear there's not a person looking at himself in a mirror, or more than three people with some having the same first name, or creatively a statue or painting, with one human looking at the artwork which is facing another human. (Would be a good one with Lisa implying the Mona Lisa, but connotations of names shouldn't be relevant)

However, what I was really curious about was the redwood question. Surprisingly, I knew the answer pretty much exactly and later noticed the complaints about using feet as a unit which was rather strange. I remembered this exact question was from a recent study in a psychology journal on cognitive biases.

It seems likely the question was written with knowledge of the study in mind, to test for anchoring bias, considering many other things could have been chosen other than the height of redwood trees in feet. I really hope the intention was not to take these results to say, "LW readers conclusively have less anchoring bias than people in the psychology study." As the maximum number that could possibly be generated by the RNG (999) iirc is lower than an anchoring number given in the study (1000), presumably few survey participants if any would answer the tree height is greater than that. Due to the RNG anchor likely being much closer to the true value anchoring bias will be less than in the psychology study by nature of how the question was presented.