One big difference is that there are theoretical cracks in the lightspeed wall that don't have any go-to-another-quantum-world analog. The Alcubierre solution to the field equations is a thing, after all. More importantly for this discussion, we can construct thought experiments about superluminal travel that have truth conditions because we know what a starfield would look like from N lightyears thataway. Quantumporting doesn't have analogues of either of those things.
But that's kind of a distraction. The interesting question for this discussion is how, if at all, the two claims "galaxies receding outside our light cone continue to exist" and "Russell's teapot exists" are different. I think we agree that there is a predictivist account of "teapot".
You assert that a predictivist definition of meaning and truth value cannot sustain an account of the "galaxies" claim, and that predictivism is therefore insufficient. I, a predictivist, deny your assertion - you have smuggled in an assumption that predictivists somehow aren't allowed to assign meaning to counterfactuals that violate physical law, which I (a predictivist) am quite willing to do as long as hypotheically violating that physical law would not bar us from being able to cash out a truth claim in expected experiences.
I believe I am a predictivist who understands predictivism correctly and consistently. I believe you are a predictivist in practice who has failed to understand predictivism in theory.
How can we investigate, confirm, or refute these claims?
Terminological point: I don't think you can properly describe your hypothetical rationalist in Stalinist Russia as "paranoid". His belief that he is surrounded by what amounts to a conspiracy out to subjugate and destroy him is neither fixated nor delusional; it is quite correct, even if many of the conspiracy's members would choose to defect from it if they believed they could do so without endangering themselves.
I also note that my experience of living in the US since around 2014 has been quite similar in kind, if not yet in degree. I pick out 2014 because of the rage-mobbing of Brendan Eich; that was the the point at which "social justice" began presenting to me as an overtly serious threat to free speech. Six years later, political censorship and the threat from cancel culture have escalated to the point where, while we may not yet have achieved Soviet levels of repression, we're closing in fast on East Germany's.
Endorsed. A lot of this article is strongly similar to an unfinished draft of mine about how to achieve breakthroughs on unsolved problems.
I'm not ready to publish the entire draft yet, but I will add one effective heuristic. When tackling an unsolved problem, try to model how other people are likely to have attacked it and then avoid those approaches. If they worked, someone else would probably have achieved success with them before you came along.
To be fair, I haven't followed Less Wrong all that closely over the years. It's more that I've known some of the key people for a while, notably Eliezer himself and Scott Alexander.
It seems to me that you've been taking your model of predictivism from people who need to read some Kripke. In Peirce's predictivism, to assert that a statement is meaningful is precisely to assert that you have a truth condition for it, but that doesn't mean you necessarily have the capability to test the condition.
Consider Russell's teapot. "A teapot orbits between Earth and Mars" is a truth claim that must unambiguously have a true or false value. There is a truth condition on on it; if you build sufficiently powerful telescopes and perform a whole-sky survey you will find it. It would be entirely silly to claim that the claim is meaningless because the telescopes don't exist.
The claim "Galaxies continue to exist when they exit our light-cone" has exactly the same status. The fact that you happen to to believe the right sort of telescope not only does not exist but cannot exist is irrelevant - you could after all be mistaken in believing that sort of observation is impossible. I think it is quite likely you are mistaken, as nonlocal realism seems the most likely escape from the bind Bell's inequalities put us in.
MWI presents a a subtler problem, not like Russell's Teapot, because we haven't the faintest idea what observing another quantum world would be like. In the case of the overly-distant galaxies, I can sketch a test condition for the claim that involves taking a superluminal jaunt 13 billion light-years thataway and checking all around me to see if the distribution of galaxies has a huge NOT THERE on the side away from Earth. I think a predictivist would be right to ask that you supply an analogous counterfactual before the claim "other quantum worlds exist" can be said to have a meaning.
Eliezer was more influenced by probability theory, I by analytic philosophy, yes. These variations are to be expected. I'm reading Jaynes now and finding him quite wonderful. I was a mathematician at one time, so that book is almost comfort food for me - part of the fun is running across old friends expressed in his slightly eccentric language.
I already had a pretty firm grasp on Feynman's "first-principles approach to reasoning" by the time I read his autobiographical stuff. So I enjoyed the books a lot, but more along the lines of "Great physicist and I think alike! Cool!" than being influenced by him. If I'd been able to read them 15 years earlier I probably would have been influenced.
One of the reasons I chose a personal, heavily narratized mode to write the essay in was exactly so I could use that to organize what would otherwise have been a dry and forbidding mass of detail. Glad to know that worked - and, from what you don't say, that I appear to have avoided the common "it's all about my feelings" failure mode of such writing.
I have run across Bucky Fuller of course. Often brilliant, occasionally cranky, geodesic domes turned out to suck because you can't seal all those joints well enough. We could use more like him.
Great Mambo Chicken and Engines of Creation were in my reference list for a while, until I decided to cull the list for more direct relevance to systems of training for rationality. It was threatening to get unmanageably long otherwise.
I didn't know there was a biography of Korzybski. Thanks!
"Galaxies continue to exist after the expanding universe carries them over the horizon of observation from us" trivially unpacks to "If we had methods to make observations outside our light cone, we would pick up the signatures that galaxies after the expanding universe has carried them over the horizon of observation from us defined by c."
You say "Any meaningful belief has a truth-condition". This is exactly Peirce's 1878 insight about the meaning of truth claims, expressed in slightly different language - after all, your "truth-condition" unpacks to a bundle of observables, does it not?
The standard term of art you are missing when you say "verificationist" is "predictivist".
I can grasp no way in which you are not a predictivist other than terminological quibbles, Eliezer. You can refute me by uttering a claim that you consider meaningful, e.g. having a "truth-condition", where the truth condition does not implicitly cash out as hypothetical-future observables - or, in your personal terminology, "anticipated experiences"
Amusingly, your "anticipated experiences" terminology is actually closer to the language of Peirce 1878 than the way I would normally express it, which is influenced by later philosophers in the predictivist line, notably Reichenbach.
The reference to the Book of the Law was intentional. The reference to chaos magic was not, as that concept had yet to be formulated when I wrote the essay - at least, not out where I could see it.
I myself do not use psychoactives for magical purposes; I've never found it necessary and consider them a rather blunt and chancy instrument. I do occasionally take armodafinil for the nootropic effect, but that is very recent and long postdates the essay.