Substrate-Independence and Nick Bostrom

[Kuznetzova]

The argument we shall present does not, however, depend on any very strong version of functionalism or computationalism. For example, we need not assume that the thesis of substrate-independence is necessarily true (either analytically or metaphysically) – just that, in fact, a computer running a suitable program would be conscious. Moreover, we need not assume that in order to create a mind on a computer it would be sufficient to program it in such a way that it behaves like a human in all situations, including passing the Turing test etc. We need only the weaker assumption that it would suffice for the generation of subjective experiences that the computational processes of a human brain are structurally replicated in suitably fine-grained detail, such as on the level of individual synapses. This attenuated version of substrate-independence is quite widely accepted.

The above quote was taken from a larger essay on the metaphysics of the universe. ("Are you living in a Simulation?"). But recently I perceive very strongly the connection between describing consciousness as purely Turing-computable function and the seemingly unrelated topic of simulating entire universes via computation.

A small list of brainstorms on my part,

• The speed of the simulation of our universe doesn't matter. It can even be paused and restarted. We would not experience the pauses or lags as we are inside of its "causal magisteria".
• If the brain is nothing but computation, in the Turing-computable sense, then this raises strange questions regarding the appearance of people in your dreams. Strict computationalism, can therefore, not rule out the possibility that the very "characters" in your dreams are themselves having internal experiences and feeling qualia. If you claim that they do not, you end up contradicting your premise that consciousness is computational. This is a vicious circle out of which I see no clear escape.
• Often Bostrom's universe simulation will contain embedded universes within those simulations. Simulations-inside-of-simulations as it were. Adopting the strict axiom that the brain produces the mind through computation only, we are faced with the real possibility of dreams inside of dreams. Embedded fractal patterns of dream illusions within illusions. And again, trying to rule this out ends up contradicting our prerequisite axiom.

The full Bostrom essay. http://www.simulation-argument.com/simulation.html

[Toadny]

The argument we shall present does not, however, depend on any very strong version of functionalism or computationalism. For example, we need not assume that the thesis of substrate-independence is necessarily true (either analytically or metaphysically) – just that, in fact, a computer running a suitable program would be conscious.

That seems like a pretty strong version of computationalism to me.

I suggest that Bostrum's assumption that a computer running a suitable program would be conscious represents the biggest mistake in contemporary philosophy of mind, not only that, the mistake is embarrassingly obvious, for reasons I sketched out in my response to your post on "The Third Rail of Consciousness".