On 1/27/2011 10:23 AM, Bruno Marchal wrote:

On 25 Jan 2011, at 15:47, Stephen Paul King wrote:

The supervenience thesis is separate from the Turing thesis and Mauldin does a good job in distinguishing them.

Just to be clear, what Maudlin call "supervenience thesis" is what I called "physical supervenience thesis", to distinguish it from the computationalist supervenience thesis. The computationalist supervenience thesis is basically what remains when we keep comp, and understand that the Phys. Sup. thesis has to go away in the comp frame.

The problem that I see is in the properties of physicality that are assumed in Mauldin’s argument. It is one thing to not be dependent on what particular physical structure a computation can be run on (assuming a realistic supervenience), it is another thing entirely to say that a Turing machine can be “run” without the existence of any physical hardware at all.

Well, in the branch ~MEC v ~MAT, Maudlin seems to prefer MAT, so he seems with you on this, I think.

I am trying to make this distinction and trying to fix this problem that I found in the supervenience thesis within Mauldin’s argument. He does point out that there are contrafactuals that must have some physical instantiation. We see this on page 411 where he wrote: “The only physical requirement that a system must met in order to instantiate a certain machine table are that (1) there must be at least as many physically distinguishable states of the system as there are machine states in the table, (2) the system must be capable of reacting to and changing the state of the tape, and (3) there must be enough physical structure to support the subjunctive connections specified in the table.” It is in the subjunctive connections that we see the contrafactuals expressed. If one’s model of physical reality does not allow for the necessary subjunctive connections to be implemented then the supervenience thesis would fail independent of the Turing thesis.


My point is that we need to be careful about what exactly do we mean by “causally inactive piece of matter”. If there is material present within a physical system that does not affect the 3 requirements above then surely we can agree with Mauldin’s claim, but if there is a problem with the faithfulness of the model of what physicality involves, then this must be fixed if possible. This is why I say that there is a bit of a straw man in his argument.

Maudlin should have said: "causally inactive piece of matter *relevant* for the computation. This is what I did, and it makes the argument independent of the counterfactual re-instantiation. The movie-graph is simpler with that respect. But this can lead to some ambiguity too.

Mathematical structures do not “do” anything, they merely exist, if at all! We can use verbs to describe relations between nouns but that does not change the fact that nouns are nouns and not verbs. The movie graph is a neat trick in that is abstracts out the active process of organizing the information content of the individual frames and the order of their placement in the graph, but that some process had to be involved to perform the computation of the content and ordering cannot be removed, it is only pushed out of the field of view. This is why I argue that we cannot ignore the computational complexity problem that exist in any situation where we are considering a optimal configuration that is somehow selected from some set or ensemble.

I don't see how this would change anything in the argument, unless you presuppose consciousness is not locally Turing emulable, to start with.

What does "locally" mean in this context? I doubt that consciousness is strictly local in the physical sense; it requires and world to interact with.


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