On 03 Sep 2005, at 07:45, Hal Finney wrote:

Bruno wrote:

Of course the reversal result introduces ambiguity in expressions
like "mental activity". That is why I sum up "comp" by YD + CT + AR.
("Yes doctor" + Church Thesis + Arithmetical realism).

But if "comp" is computationalism, that is the doctrine that our
mental processes can be modelled/reproduced by computational activity.
This would seem to correspond to Bruno's "Yes Doctor".  That is, you
say "yes" to a doctor who wants to replace your mind with a computer,
at least if it is done carefully and correctly.  If you believe in
computationalism, then you should believe that a computer could reproduce and substitute for the activity of your mind. (Some people have qualms about the details of the transfer process from the mind to the computer,
but they are often satisfied if the change is done slowly, perhaps one
neuron at a time.)  Likewise if you would accept that your mind could
be substituted by a computer, you are a computationalist.

So where do the Church Thesis and Arithmetical realism come into play
as part of the DEFINITION of "comp"?  I don't understand this.

This is just because I make a deductive reasoning from YD, at first, but at the step 7 I need the universal dovetailer to be enough general, that is really "universal", and this is made simple by CT. Well, even at step 0 (Yes doctor), if the doctor is honest it will warn you that the artificial brain is a digital device, and I cannot imagine him explaining what that really means in all generality without invoking Church thesis. Church thesis also simplifies considerably many reasoning with comp. The conceptual explanation is given in my two diagonalization posts. We can come back on this. Arithmetical realism is a much weaker assumption. I have introduce it in comp to provide a way out for those who believes in YD and in Church thesis (quasi all computer scientist I met) but still doesn't not believe in the conclusion although agreeing with most of the steps. looking in the detail it is the arithmetical realist assumption which they find the most weak.
But I agree with Godfrey that CT and AR are really bodyguard for YD.
But then, with the interview of the lobian machine, the physics is derived from CT and AR alone!

To sum up: comp is essentially YD, if only to provide a picture of the first person comp indeterminacy. But CT is used to give a range for that indeterminacy (the UD*, the trace of the UD). It is by CT that the UD is really comp-universal, and it is a consequence of CT that this forces it to dovetail, and to dovetail on an incredibly redundant structures (providing non trivial relative measures). AR is used to just accept the notion of UD* and other infinite mathematical structures, and for justifying the use of the excluded middle principle.

Given the apparent "enormity" of the reversal conclusion, I have no choice than to put all the card on the table. A referee of my french PhD thesis has try to convince me that the use of CT can be avoided in UDA. I am not convinced, and then I know it is unavoidable in the UDA lobian translation.

Hope that helps,



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