So discussing one of my favorite books (Permutation City by Greg Egan) it dawned on me how to formulate a (limited) form of an argument I’ve long found convincing. I will, of course, assume that there is an objective fact about whether certain items have experiences and that people do and tables do not, i.e., rejecting Panpsychism.

In any case take the (far too) widely assumed thesis of strong AI, namely that any two processes that execute the same calculations will have the same experiences. For instance any computer that simulated the human brain would have all the same experiences as that person. Note that this is much stronger than merely saying we could build some machine that simulated the human brain and had the same experiences as it tells us that it doesn’t matter how we simulate it.

Now in order for this thesis to make sense we must have some notion of when a certain physical device implements a given calculation. Of course the natural way to phrase this is in terms of some kind of counterfactuals. However, this means that we would need to buy into a substantive notion of physical cause. There would need to be an extra meta-physical entity that somehow makes one description of the actual events in the universe the ‘true’ laws that really support counterfactuals while other predictively equivalent ones are wrong. Note that being a Lewis style realist about possible worlds is not sufficient either as you would need to believe that the closeness relation was somehow real/had metaphysical backup as well.

In fact if we are Humans about causation it seems that there is no hope for us. Since there is no (objectively) privileged statement of the laws we can transform any actual result into a computation. If we want to conclude that the decay of an atom implements a certain calculation we just decide what the output of the computation should be (say 1) and pick an equivalent (in our world) formulation of the physical laws that says (assuming the atom did decay) the atom decays if and only if the output of the computation is a 1. Obviously if we want to break up some complex computation into many small pieces we surely can. In particular we can interpret the random thermal motion of a table to be the simulation of a brain.

Now perhaps you will try to object that simple descriptions of the laws are somehow privileged. Even if so it seems you still need some fact which makes them objectively privileged. If all being simple amounts to is that human beings take a certain attitude toward them you haven’t gotten very far. It would appear that the very intuitions that motivate the strong AI view, namely that there isn’t extra spooky non-physical facts that determine what events cause experiences, is undermined as the very position sees to require we have these non-physical facts about what the ‘right’ way to write the physical laws is.

Probably this argument has been made in some form before but it occurred to me today and I’m stalling on my math.