> If we replicated a human brain cell by cell wouldn’t that thing be conscious?
If we copied a human brain, assuming it were possible, what we'd be left with is two human brains. But I doubt either could be conscious, but even if they both were, they're still human brains, not computers. The mistake is confusing artificial intelligence with human intelligence, and the exercise would be like something out of a Mary Shelley novel and not computer science.
A computer can simulate a physical process; if the intelligence in a human brain is physical in origin, a sufficiently powerful computer can simulate it. Such a simulation can reasonably be described as a "copy".
The question then is "how powerful a computer", and nobody knows that, because even the lower bound estimates are too expensive to bother with at present.
A simulation is not the real thing. We can simulate forces and interactions between simulated particles, but neither would have the actual properties of the real thing, only simulated properties. Simulated magnetism is not magnetic. It is just an appearance, an illusion. Consciousness only arises from actual, genuine healthy brain, not simulated brain. A simulated brain can no more be conscious than a video game.
That argument requires that consciousness is a substance rather than a process.
If consciousness is a substance, and not an emergent feature of data that just happens to be processed in us via the medium of electrochemical pathways pumping protons across cell walls, then it is natural to ask if this substance remains after death[0], or precedes birth, or passes between creatures (not necessarily all human) in a cycle of reincarnation[1], or even between living and non-living things like rocks and rivers[2].
Nobody has found significant evidence of such a substance, though they have been looking.
If we copied a human brain, assuming it were possible, what we'd be left with is two human brains. But I doubt either could be conscious, but even if they both were, they're still human brains, not computers. The mistake is confusing artificial intelligence with human intelligence, and the exercise would be like something out of a Mary Shelley novel and not computer science.