Stated as claims that I'd endorse with pretty high, but not certain, confidence:
Note that this is not a claim that something like RLHF is somehow impossible. RLHF, and other RL-adjacent techniques that have reward-equivalents that would never realistically train from scratch, get to select from the capabilities already induced by pretraining. Note that many 'strong' RL-adjacent techniques involve some form of big world model, operate in some constrained environment, or otherwise have some structure to work with that makes it possible for the optimizer to take useful incremental steps.
One simple story of many, many possible stories:
1. It's 20XY. Country has no nukes but wants second strike capacity.
2. Nukes are kinda hard to get. Open-weights superintelligences can be downloaded.
3. Country fine-tunes a superintelligence to be an existential threat to everyone else that is activated upon Country being destroyed.
4. Coordination failures occur; Country gets nuked or invaded in a manner sufficient to trigger second strike.
5. There's a malign superintelligence actively trying to kill everyone, and no technical alignment failures occurred. Everything AI-related worked exactly as its human designers intended.
[I'm posting this as a very informal community request in lieu of a more detailed writeup, because if I wait to do this in a much more careful fashion then it probably won't happen at all. If someone else wants to do a more careful version that would be great!]
By crux here I mean some uncertainty you have such that your estimate for the likelihood of existential risk from AI - your "p(doom)" if you like that term - might shift significantly if that uncertainty were resolved.
More precisely, let's define a crux as a proposition such that: (a) your estimate for the likelihood of existential catastrophe due to AI would shift a non-trivial amount depending on whether that proposition was true or false; (b) you think there's at least a non-trivial probability that the proposition is true; and (c) you also think there's at least a non-trivial probability that the proposition is false.
Note 1: It could also be a variable rather than a binary proposition, for example "year human-level AGI is achieved". In that case substitute "variable is above some number x" and "variable is below some number y" instead of proposition is true / proposition is false.
Note 2: It doesn't have to be that the proposition / variable on it's own would significantly shift your estimate. If some combination of propositions / variables would shift your estimate, then those propositions / variables are cruxes at least when combined.
For concreteness let's say that "non-trivial" here means at least 5%. So you need to think there's at least a 5% chance the proposition is true, and at least a 5% chance that it's false, and also that your estimate for p(existential catastrophe due to AI) would shift by at least 5% depending on whether the proposition is true or false.
Here are just a few examples of potential cruxes people might have (among many others!):
Listing all your cruxes would be the most useful, but if that is too long a list then just list the ones you find most important. Providing additional details (for example, your probability distribution for each crux and/or how exactly it would shift your p(doom) estimates) is recommended if you can but isn't necessary.
Commenting with links to other related posts on LW or elsewhere might be useful as well.