The main disagreement between Aaronson's idea and LW ideas seems to be this:
If any of these technologies—brain-uploading, teleportation, the Newcomb predictor, etc.—were actually realized, then all sorts of “woolly metaphysical questions” about personal identity and free will would start to have practical consequences. Should you fax yourself to Mars or not? Sitting in the hospital room, should you bet that the coin landed heads or tails? Should you expect to “wake up” as one of your backup copies, or as a simulation being run by the Newcomb Predictor? These questions all seem “empirical,” yet one can’t answer them without taking an implicit stance on questions that many people would prefer to regard as outside the scope of science.
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As far as I can see, the only hope for avoiding these difficulties is if—because of chaos, the limits of quantum measurement, or whatever other obstruction—minds can’t be copied perfectly from one physical substrate to another, as can programs on standard digital computers. So that’s a possibility that this essay explores at some length. To clarify, we can’t use any philosophical difficulties that would arise if minds were copyable, as evidence for the empirical claim that they’re not copyable. The universe has never shown any particular tendency to cater to human philosophical prejudices! But I’d say the difficulties provide more than enough reason to care about the copyability question.
LW mostly prefers to bite the bullet on such questions, by using tools such as UDT. I'd be really curious to see Aaronson's response to Wei's UDT post.
As far as I can see, the only hope for avoiding these difficulties is if—because of chaos, the limits of quantum measurement, or whatever other obstruction—minds can’t be copied perfectly from one physical substrate to another, as can programs on standard digital computers.
Even if Aaronson's speculation that human minds are not copyable turns out to be correct, that doesn't rule out copyable minds being built in the future, either de novo AIs or what he (on page 58) calls "mockups" of human minds that are functionally close enough to the ori...
Scott Aaronson has a new 85 page essay up, titled "The Ghost in the Quantum Turing Machine". (Abstract here.) In Section 2.11 (Singulatarianism) he explicitly mentions Eliezer as an influence. But that's just a starting point, and he then moves in a direction that's very far from any kind of LW consensus. Among other things, he suggests that a crucial qualitative difference between a person and a digital upload is that the laws of physics prohibit making perfect copies of a person. Personally, I find the arguments completely unconvincing, but Aaronson is always thought-provoking and fun to read, and this is a good excuse to read about things like (I quote the abstract) "the No-Cloning Theorem, the measurement problem, decoherence, chaos, the arrow of time, the holographic principle, Newcomb's paradox, Boltzmann brains, algorithmic information theory, and the Common Prior Assumption". This is not just a shopping list of buzzwords, these are all important components of the author's main argument. It unfortunately still seems weak to me, but the time spent reading it is not wasted at all.