# Re: UDA Step 7

```Dear Günther,
```
```
Le 02-avr.-08, à 20:16, Günther Greindl a écrit :

>
> Dear Bruno,
>
>> Yes. The comp "intelligible matter" hypostases give the modal logic
>> corresponding to quantum logic, except that I loose the necessitation
>> rule.
>> The significance of this remains to be seen of course.
>
> Ok I get it. I will reread your papers :-) (too much new stuff in one

I am aware. Sorry. I will perhaps explain a bit more the
"methodological problem" is an answer to a post by Tom.
Soon or later.

>
>> In a nutshell, the restriction to the sigma_1 sentences *is* the
>> translation of the comp hyp in the language of a Lobian machine.
>> Why?
>> Because you can characterize a Turing Universal Prover Machine by the
>> fact that she can prove all true Sigma_1 sentences. So Turing
>> Universality can be defined by the modal formula p -> []p, for p
>> sigma_1. A lobian machine is not only universal, but "knows" that she
>> is universal, i.e. she can prove all the formula p -> []p for p
>> Sigma_1. Adding the axiom p -> []p to the logic G, gives the
>> self-reference logic of the computationalist lobian machine. The
>> Universal Dovetailer is equivalent to the set of true sigma_1
>> sentences
>> together with their many proofs.
>> This is explained at the end of most of my papers, but needs some
>> amount of knowledge of recursion theory.
>
> Ah OK; I am going to do some recursion theory this semester. (the
> Rogers
> book :-)

It is the best.

> Could you recommend something on modal logic?

I would recommend the following one:

Chellas, 1980
Chellas, B. F. (1980). Modal Logic, an introduction. Cambridge
University Press, Cambridge.

>
>
>> Hmmm... I would say that 3rd person white rabbit appear when there are
>> too much universes with aberrant histories. Too much universes with
>> too
>> much talking white rabbits having clocks in their hands and saying
>> "too
>> late, too late ..."?
>
> Yes that is what I meant.
>
>>> but I think
>>> they are also aware of first person white rabbit, as they discuss the
>>> Boltzmann brain quite literally as a "brain" in some papers - which
>>> just
>>> oozes away after some time or immediately after "cogito ergo sum".
>>
>>
>> I don't understand. (In general the first person is forgotten or
>> assimilated to third person constructs like brain through some
>> identity
>> thesis, this cannot work by the Movie Graph argument or by Maudlin's
>> Olympia: we have discuss this).
>
> Now I don't understand; I am aware of Maudlin's Olympia, though not of
>
> How do you mean the first person is forgotten?

A bit like the way of the so called Eliminative Materialist" (cf the
Churchland). The (hard) problem of consciousness and/or the mind
problem is(are) so difficult that somme people hide it into a pure
language problem or a problem referring to things which would not be
existing, like if consciousness would be an illusion. I think that in
this list people generally agree that consciousness or mind exists.
Epiphenomenalism, the idea that consciousness exists but has no role or
no function, is also a manner to make the person, and its will,
disappear.
Of course I do think that once we assume seriously the computationalist
hypothesis in the cognitive sciences, we have to "eliminate" the
substantial primary matter idea, but this goes against many years
(centuries) of naive aristotelianism, itself a product of millions
years of "Darwinian Evolution": the cat is better not doubting the
reality of the mouse if he want to survive ...
Do you agree that consciousness cannot be an illusion unlike everything
else? To be illusional, you have to be conscious of something. But
everything else can be doubted: body, matter, universe(s), etc.

Have a good day,

Bruno

PS thanks to the reference to Bostrom's paper. I have put it on my USB
key, and I will read it at home tonight.

http://iridia.ulb.ac.be/~marchal/

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