Let's start in the middle, where you say I wrote "When you have digitally modeled a brain such that the model responds to its inputs as a brain does, then you h

Let's start in the middle, where you say I wrote "When you have digitally modeled a brain such that the model responds to its inputs as a brain does, then you have built a brain." What I actually wrote was this: "Then, presumably, you will also hold that when you have digitally modeled a brain such that the model responds to its inputs as a brain does, then you have built a brain." This has to be read in the context of the post by ratelimitsteve to which I was replying: I am not saying that I think that when you have digitally modeled a brain such that the model responds to its inputs as a brain does, then you have built a brain, I am saying it is something that ratelimitsteve would have difficulty denying while being consistent with his distinction between simulating and building. Personally, I would not say that simulating a brain to this extent amounts to building a brain, as that seems to me to be unnecessarily awkward usage that I feel will lead to confusion without making anything clearer. I would still call it a simulation, albeit one that might justifiably be called functionally isomorphic to a biological brain if it were good enough. I would describe the relationship between an Enigma machine and a digital simulation of one in the same terms, and if I possessed an actual Enigma machine, I would not willingly swap it for a digital simulation! With that said, let's go back to your second paragraph: "You say that the physical hardware your enigma simulation runs on provides the causal element..." Yes. The design of the physical Enigma device contains an abstract specification of how outputs are to be generated from inputs, such that when the machine is used, physics ensures that the correct output for any valid input is generated as a consequence of the causal relationships between its components. In the same way, the software of its digital simulator contains an abstract specification of how outputs are to be generated from inputs, such that when the program is run on a sufficiently capable computer, physics ensures that the correct output for any valid input is generated as a consequence of the causal relationships between its components, once the program has been loaded. "...but the simulation of the nuclear reactor also runs on physical hardware. Yet it obviously doesn't provide the causal element..." Correct, insofar as a computer is not capable of undergoing nuclear fission, regardless of how it is programmed. "...and neither does the enigma machine simulation's hardware. There are no spinning gears for example." No - these two cases are not equivalent. Nuclear fission is required for a nuclear reactor to function, but rotating gears are not required for encrypting or decrypting a message according to the enigma machine's abstract specification; they are just how the specification happens to be implemented in the machine. "...Hence why you and I both call it a simulation, I think we're in agreement here." Well, we both seem to be in agreement as to what to call it, but apparently not over why we think that. In next paragraph ("I think you could argue that..") you say you could agree that the essence of the enigma machine is not grounded in physical reality, it's the abstract relationships we're talking about. I am OK with that so long as it is understood that some sort of implementation is required for anything to happen. Now we get to the misunderstanding of my reply to ratelimitsteve, covered above, and after that you go on to say "the claim is that the essence of the brain is the abstract relationships, correct?" My response to this is the same as with regard to the essence of an Enigma machine: I am OK with that so long as it is understood that some sort of implementation is required for anything to happen. The next paragraph begins "The problem I see is that consciousness is a physical phenomenon...", and I tend to agree with the claim (though not that it is a problem) again in the sense that some sort of implementation seems to be required for anything to happen. I don't claim to be able to prove this, let alone explain how it works in brains, it just seems to me that there's no plausible alternative. Then you write "In fact it seems like it's the magnum opus of phenomenon, in that all our experience comes from our consciousness..." To me, this appears to be a version of Cartesian doubt, about which I am extremely skeptical, in this sense: I think it is tendentious for anyone to invoke it only when it greases a sticky argument, while otherwise acting, speaking and arguing as if our sensory experiences give us reliable information about an external world. Finally, we get to the crux of the matter: "you have to then bridge the gap between the simulation and physical reality." Here you just declare there to be a gap between the simulation and physical reality, but to my mind, nothing you have written up to this point provides any justification for thinking there is a gap that needs to be bridged. As best I can tell, you feel that by emphasizing the abstract nature of what you call the essence of a simulation you have divorced it from the physical, and my response to that has been, consistently, to point out that these abstractions do not get anything done unless they have some implementation, and there is no evidence of those implementations being in any sense non-physical.