On 3/7/07, Mitchell Porter <[EMAIL PROTECTED]> wrote:
From: "Stathis Papaioannou" <[EMAIL PROTECTED]> >But the problem with ontological type arguments is that they allow you to >conjure up anything you like by simply defining it as existing. If there is >a physical reality, things don't work like that. Statements of mathematics >and logic, however, are necessarily true (or false). This is what I meant >by >saying that mathematical structures exist necessarily: not that "17 is >prime" means you may meet a prime-looking number 17 walking down the >street, >but that 17 is necessarily prime, and not even God can change that. So *if* >there is no separate physical reality, and what we always thought of as >physical reality is just mathematical reality, it would solve the problem >of >why something rather than nothing exists, or why God exists, or why God >made >the world. I haven't seen this line of argument before. But you could equally say "A bachelor is necessarily unmarried", and thereby "deduce" that the existence of bachelors is apriori necessary. And you can get away from the apparent ontological commitment of saying "17 is prime" by playing Russell's game of rearranging the natural-language statement of a proposition in order to reveal its true logical form, and announcing that what's *really* being said is "*If* 17 existed, *then* it would necessarily be prime". You don't get the existence of anything for free, that way.
This is so if there is a real physical world as distinct from the mathematical plenitude. If there is no such separate physical world, then it isn't possible for something to be blessed with this quality of existence, because everything that is logically consistent exists. Of course, then you have to explain why we find ourselves in a corner of the Plenitude where the familiar laws of physics apply, rather than my keyboard suddenly turning into a fire breathing dragon (the failure of induction). The easy answer is to invoke the anthropic principle: we observe only those universes which give rise to observers like us. The difficult answer is to try to define some measure on the mathematical structures in the Plenitude and show that orderly universes like ours thereby emerge. See this paper for an example of this sort of reasoning: http://parallel.hpc.unsw.edu.au/rks/docs/occam/
Then there is the question of what it means to implement a computation. If >you look at it the right way, anything could be a computation. This has >been >given by John Searle as a reductio ad absurdum against computationalism, >and >explored by several other authors (eg. Hilary Putnam, David Chalmers, Greg >Egan). The usual counterargument is that in order to map a computation onto >an arbitrary physical process, the mapping function must contain the >computation already, but this is only significant for an external observer. >The inhabitants of a virtual environment will not suddenly cease being >conscious if all the manuals showing how an external observer might >interpret what is going on in the computation are lost; it matters only >that >there is some such possible interpretation. Moreover, it is possible to map >many computations to the one physical process. In the limiting case, a >single state, perhaps the null state, can be mapped onto all computations. It's an odd sort of mapping! Look at it from the other direction. Suppose that in reality, we have an object sitting there, doing nothing - in the 'null state'. You say that all possible computations are being implemented there. What are you doing, reinterpreting the null state from moment to moment so as to make it 'mean' whatever you want it to mean? This is angels-dancing-on-a-pin stuff. At least functionalists insist that there's structure on *both* ends of the mapping.
You could put a constraint on what counts as an implementation of a computational or mental state if you insist on interaction with an environment. A coal-digging robot has the coal-digging experience when it is actually digging for coal, and as per functionalism it would have the same experience if its program were run on different hardware with the same result. You could find such a robot left behind by an alien civilization and through trial and error work out what it's supposed to do. However, what if you put the environment inside the computer, with no inputs? If you found such an alien computer, it would be impossible to determine what it was thinking about without extra information, like trying to determine what an alien string of symbols means. There is, of course, the originally intended meaning, but once we remove the constraint of environmental interaction, what is there left for the computer itself, or for an external observer, to distinguish between the original meaning and every other possible meaning it may have had? The problem is with the physical supervenience thesis that usually goes together with computationalism. If we consider that mind is generated by computation on an abstract machine, we can keep computationalism and drop physical supervenience. This would also answer Tim Maudlin's objection to the supervenience thesis in his 1989 paper "Computation and Consciousness". Stathis Papaioannou ----- This list is sponsored by AGIRI: http://www.agiri.org/email To unsubscribe or change your options, please go to: http://v2.listbox.com/member/?list_id=11983
