On 03 Sep 2005, at 07:45, Hal Finney 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
and substitute for the activity of your mind. (Some people have
about the details of the transfer process from the mind to the
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,