Thanks for clarifying that! I think there are few reasons to be wary of whole brain emulation as a route to super-intelligence (see this from Mandelbaum: https://philpapers.org/rec/MANEAM-4). Now I’m aware that if whole brain emulation isn’t possible, then some of the computationalist assumptions in my post (namely, that the same limits on Turing machines apply to humans) seem less plausible. But I think there are at least two ways out. One is to suppose that computation in the human brain is sub-neural, and so brain emulation will still leave out important facets of human cognition. Another is to say that whole brain emulation may still be plausible, but that there are speed limits on the computations that the brain does that prevent the kind of speeding up that you imagine. Here, work on the thermodynamics of computation is relevant.
But, in any event (and I suspect this is a fundamental disagreement between me and many longtermists) I’m wary of the argumentative move from mere conceivability to physical possibility. We know so little about the physics of intelligence. The idea of emulating a brain and then speeding it up may turn out to be similar to the idea of getting something to move at the speed of light, and then speeding it up a bit more. It sounds fine as a thought experiment, but it turns out it’s physically incoherent. On the other hand, whole brain emulation plus speed-ups may be perfectly physically coherent. But my sense is we just don’t know.
Thanks for clarifying that! I think there are few reasons to be wary of whole brain emulation as a route to super-intelligence (see this from Mandelbaum: https://philpapers.org/rec/MANEAM-4). Now I’m aware that if whole brain emulation isn’t possible, then some of the computationalist assumptions in my post (namely, that the same limits on Turing machines apply to humans) seem less plausible. But I think there are at least two ways out. One is to suppose that computation in the human brain is sub-neural, and so brain emulation will still leave out important facets of human cognition. Another is to say that whole brain emulation may still be plausible, but that there are speed limits on the computations that the brain does that prevent the kind of speeding up that you imagine. Here, work on the thermodynamics of computation is relevant.
But, in any event (and I suspect this is a fundamental disagreement between me and many longtermists) I’m wary of the argumentative move from mere conceivability to physical possibility. We know so little about the physics of intelligence. The idea of emulating a brain and then speeding it up may turn out to be similar to the idea of getting something to move at the speed of light, and then speeding it up a bit more. It sounds fine as a thought experiment, but it turns out it’s physically incoherent. On the other hand, whole brain emulation plus speed-ups may be perfectly physically coherent. But my sense is we just don’t know.