Le 12-nov.-05, à 14:53, uv a écrit :

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[bruno]Now, the "real" important things to grasp for making clear the way I use modal logic, consists in understanding the theorem of Solovay. Have you heard about it? It generalizes in some way the theorem of Godel and the theorem of Lob. it makes precise the connection between modal logic and the logic of arithmetical reference.[uv] I understand that "Solovay's theorem is so significant because it shows that an interesting fragment of an undecidable formal theory like Peano Arithmetic -- namely that which arithmetic can express in propositional terms about its own provability predicate -- can be studied by means of a decidable modal logic, GL, with a perspicuous possible worlds semantics." As such it should be very relevant, I most certainly agree - but how does it relate to "quantum suicide" ? [uv] I could not work out how it relates to quantum suicide and first or third persons in your papers "mechanism and personal identity" or "amoeba, planaria and dreaming machines" or "Computation,Consciousness and the Quantum" or "The Origin of Physical Laws and Sensations" but the logic of the matter has to be considered, as you say.

`Indeed the link with quantum suicide and comp suicide are in my older`

`paper "Informatique théorique et philosophie de l'esprit, Toulouse`

`1988". Also explained in my 1991 paper "Mechanism and personal`

`identity".`

`With Kripke, to say Bp is true in the observer moment (OM) alpha means`

`p is true in each accessible from alpha observer moment beta. The`

`problem is that with comp, or just with the lobian interview, each OM`

`can access to a cul-de-sac world (Dt -> DBf). In cul-de-sac worlds, it`

`follows by elementary classical propositional calculus that Bf is true,`

`so Bp cannot be taken as the probability of p is one. So we have to`

`postulated explicitly the consistency of the the proposition we are`

`proving, and this correspond to the passage from`

Bp, to Bp & Dp The second Theatetic trick! Define a new bow Cp by Bp & Dp in G.

`Now G* (the propositional truth theory on the machine's`

`provability/consistency) proves that Bp is equivalent with Bp & Dp. But`

`the machine itself (G) cannot, and this makes the logic of Bp & Dp`

`quite different of G, and non trivial.`

`(And then the comp hyp itself can be shown equivalent with adding "p ->`

`Bp" to G, then if comp is true the logic should give the "propositional`

`physics", and give indeed already logics belonging to the family of`

`quantum logics.`

[bruno]If you are interested I could try to say more, and that could perhaps helps me to present the result I thjink I got. I do have underestimated the novelty of mathematical logic for the physicists. I know physicists who have a rather good understanding of the incompleteness theorems, but I realize they does not know the completeness theorems, which is indeed the background making what logic really consists in. Other people asks me similar questions so that I will try to post better synthetical summary of what I have try (at least) to communicate. Bruno[uv] Anything you can add on quantum suicide seems interesting to me. In particular, where does the difference between death and loss of consciousness fit in, for example?

`3-death and 3-loss of consciousness are alike, except we can have more`

`hope in the latter. 1-death and 1-loss-of-consciousness have no`

`meaning, I would say, although lack of coffee in the morning can create`

`some trouble which we could easily confuse with some first person`

`paradoxical apprehension of its own lack of consciousness, like a`

`zombies complaining nobody want to believe they are zombies!`

[uv] And does it make all that much difference in that scheme whether a person is PERMANENTLY removed from the system or just REMOVED FOR A SPACE.

Remember I don't postulate a physical primitive world.

There are a lot of ways that can be done, possibly with very different parameters. (e.g. like in Parfit's conjectures, which involved identity in even very specific examples like say a long spell in prison). Something like 30-40% of people get hypnagogic myoclonus and that is another (slightly differing) case.

Could you tell me what is a myoclonus? Bruno http://iridia.ulb.ac.be/~marchal/