If the function is reproduced, the material it runs on should not matter

The argument

Proponents of this position argue that consciousness is a matter of what a system does rather than what it is made of. The brain's neurons achieve their effects by taking in signals, transforming them and passing them on. If each of those operations can be described, then each can in principle be carried out by some other component, and a system built from those components would perform the same operations in the same arrangement. The claim is that whatever the original arrangement produced, the copy would produce too. The point is often pressed by imagining the replacement done gradually: one neuron is substituted for a functionally identical artificial unit, then another, with behaviour and reports unchanged throughout. Proponents argue that there is no principled moment at which consciousness could be said to depart, and that a position committed to its departing somewhere must identify where and why. Absent such an account, they hold, the insistence on biology is a preference for familiar materials dressed up as a metaphysical requirement. Proponents accept that current machines are not organised anything like brains, and treat this as a statement about engineering rather than about possibility. The objection that computers merely store information in fixed blocks while brains process it through dense, adaptive connections describes one architecture, not all architectures; systems whose connections are weighted, revisable and massively interconnected are precisely what the objection says machines cannot be. Because consciousness is constituted by the functional organisation of a system rather than by its substrate, this argument concludes, a sufficiently organised machine can be conscious.

Premises

Counter-arguments

Opponents reply that this treats consciousness as the one phenomenon that comes into existence by being accurately described. A program can model digestion in full detail without digesting, and a simulated hurricane leaves the room dry; no reason has been given for the exception. They add that the brain is not merely a signal-passing network but living tissue whose activity is chemical, continuous and bound to a body with needs that can be harmed, and that reproducing its outputs is not instantiating it.

Rejecting the premises

[Rejecting P1] That the brain's operations admit of a functional description does not establish that consciousness is produced by what such a description captures. The premise assumes the functional account is complete, and that is exactly what the opposing case denies. [Rejecting P2] Implementability in other components holds for the function as described. If consciousness depends on properties of the medium rather than on organisation alone, the premise's appeal to what is possible in principle does not reach it. [Rejecting P3] This step restates the conclusion. That a system reproducing an organisation reproduces whatever that organisation produces is true only if the production depends on organisation and nothing else, which is what the argument set out to establish.