Bruno Marchal writes:

> which invokes an argument discovered by Bruno and Tim Maudlin > demonstrating that there is a problem with the theory that the mental > supervenes on the physical. It seems that to be consistent you have to > allow either that any computation, including the supposedly conscious > ones, supervenes on any physical activity,

I'm afraid this does not follow from Maudlin (1989) or me (1988). It is more related to the Putnam, Chalmers, Mallah (in the list) implementation problem. Maudlin shows that if comp is true and if physical supervenience is true then consciousness supervenes on no physical activity at all. From this absurdity he derives a problem for comp. Having comp as main hypothesis, I derive from such absurdity the difficulty of maintaining the physical supervenience theory. But even with just quantum mechanics, the notion of physical supervenience is not entirely clear.

Maudlin starts off with the assumption that a recording being conscious is obviously absurd, hence the need for the conscious machine to handle counterfactuals. If it were not for this assumption then there would not have been much point to the rest of the paper. Actually, Putnam and Chalmers also think that the idea of any physical system implementing any computation is absurd. I am not sure of Mallah's position (he seems to have disappeared from the list after I joined), but Hal Finney seemed to give some credence to the idea, and outside the list Hans Moravec and Greg Egan seem also to at least entertain the possibility that it is true. I would be interested if anyone is aware of any other references. Although you have clearly stated that the two ideas - consciousness supervening on all physical processes and consciousness supervening on no physical process - are completely different I think they are related in that in both cases matter is irrelevant to consciousness, and we may as well say that what is important is computation as platonic object, not its accidental correlation with (putative) real world processes. They are also closely related in that the main argument against them is "that's absurd". A second argument against them is also the same: the difficulty explaining why we don't suddenly find ourselves in "white rabbit" universes.
> or that computations do not supervene on physical activity at all but > are complete in themselves, consciousness included, by virtue of their > status as Platonic objects. Bruno concludes that the latter is the > case, but Maudlin appears to take both possibilities as obviously > absurd and thus presents the paper as a problem with computationalism > itself.

Well, if you read carefully Maudlin, he concludes that throwing out comp does not solve his problem. He is aware that the problem is more related to physical supervenience than with comp. What is strange, with Maudlin, is that he wrote an excellent book on Bell's inequality and he seems aware that "matter" is not an easy concept too (so I don't understand why he feels so sorry for abandoning physical supervenience, when such a concept is not even clear once you understand that "quantum matter" is not well defined.

Throwing out comp throws out physical supervenience as well, so it can eliminate the problem. Keeping comp and throwing out physical supervenience is the tricky thing.

>> MP: Why are we not zombies? The answer is in the fact of >> self-referencing. In our case [as hominids] there are peculiarities >> of construction and function arisen from our evolutionary history, >> but there is nothing in principle to deny self-awareness from a >> silicon-electronic entity that embodied sufficient details within a >> model of self in the world. The existence of such a model would >> constitute its mind, broadly speaking, and the updating of the model >> of self in the world would be the experience of self awareness. What >> it would be like TO BE the updating of such a model of self in the >> world is something we will probably have to wait awhile to be told >> :-)
> It seems reasonable to theorise that if an entity could behave like a > conscious being, it must be a conscious being.

It is the no-zombie theory. One question is: "could behave like" for how long? Now this question makes sense only for those who take the physical supervenience for granted. But then with comp, accepting my argument + Maudlin (say), there is no problem at all: consciousness of one individual supervene on an infinity of immaterial computations, never on anything singularized, by Matter or anything else. Matter's role consists in "assembling" coherent dream so that consciousness can manifest themselves relatively to other consciousness. The "essence" of matter relies in the possibility of inter-subjective constructions.

> However, the theory does not have the strength of logical necessity. > It is quite possible that if nature had electronic circuits to play > with, beings displaying intelligent behaviour similar to our own may > have evolved, but lacking consciousness. This need not lead to the > usual criticism: in that case, how can I be sure my fellow humans are > conscious? My fellow humans not only behave like me, they have a > biological brain like me. We would have to invoke magic to explain how > God has breathed consciousness into one person but not another, but > there is no such theoretical problem if the other person turns out to > be a robot. My personal view is that if a computer simply learned to > copy my behaviour by studying me closely if it were conscious it would > probably be differently conscious. If the computer attempted to copy > me by emulating my neuronal activity I would be more confident that it > was conscious in the same way I am, although I would not be 100% > certain. But if I were copied in a teleportation experiment to a > similar tolerance level as occurs in normal moment to moment living, > it would be absurd to seriously contemplate that the copy was a zombie > or differed significantly in his experiences from the original.

Yes, ok.



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