On 25 Sep 2013, at 23:11, Telmo Menezes wrote:

On Wed, Sep 25, 2013 at 4:52 PM, Bruno Marchal <marc...@ulb.ac.be>wrote:On 25 Sep 2013, at 15:50, Telmo Menezes wrote:On Mon, Sep 23, 2013 at 7:49 PM, Bruno Marchal <marc...@ulb.ac.be>wrote:On 23 Sep 2013, at 12:41, Telmo Menezes wrote: <snip> Thus your interest in near-death experiences?Yes. And in all "extreme" altered state of consciousness. Thoseextremecases provide key information.Can this information be recovered?A part of it, but it is experiential and not really communicable orrationally justifiable. The wise searcher will remain mute on this,or beprecise that it gives only a report of an experience, or perhapssuggests a(meta) theory in which such experience exists and are notcommunicable.Ok.For example, is a NDE that did not result in death, was it really a cul-de-sac?I would say no. But this is complex question, and the salviaexperienceconfused me on this topic.In the NDE, people come back, but with salvia, locally, people doesnot comeback, only an approximative copy.I read several reports on this sensation of having been copied. It's very intriguing.

`I agree. It is *very* intriguing. I thought even that salvia somehow`

`refutes comp, but I realize that it was only from the first person`

`perspective, and this is coherent with the fact that the "knower" (Bp`

`& p) is already quite comp resistant.`

`It is the diabolical aspect of comp: it predicts that the machine have`

`necessarily an hard time with comp. Somehow, like the Gödelian`

`sentence, comp says about itself "you can't really believe me". From`

`that perspective salvia plays a similar trick, just very realistically!`

That's why i say that salvia is not an NDE, but a DE. That is whyit can bequite literally "life changing", and why I would not recommend it to anybody.For the feeler or observer there is no cul-de-sac (thanks to the "&Dt"added to the Bp, by Gödel's completeness theorem (notincompleteness!).But the scientist part of him has cul-de-sac, perhaps the publishor perish,that is the fact that proofs must be finite, before publication. But it is hard to interpret all this literally. Caution.Sure.We should *try* to avoid it, but we can't avoid it withoutloosing ouruniversality.The consistent machines face the dilemma between security andlack offreedom-universality. With <>p = ~[] ~p, here are equivalent waytowrite it: <>t -> ~[]<>t <>t -> <> [] f []<>t -> [] f I don't understand how you arrive at this equivalence.I use only the fact that (p -> q) is equivalent with (~q -> ~p)(thecontraposition rule, which is valid in classical propositionallogic),andthe definition of <> p = ~[] ~p. I use also that ~~p isequivalent withp. Note that []p = ~~[]~~p = ~<> ~p. And, ~[]p = <> ~p and ~<>p = [] ~pLike with the quantifier, a not (~) jumping above a modal signmakes itinto a diamond, if it was a bo, and a box, if it was a diamond. Starting from <>t -> ~[]<>t.But where does <>t -> ~[]<>t come from?<>t -> ~[] <> t is the same as ~[] f -> ~[] (~[] f) OK?Ok.And that is .... the modal writing of Gödel's second incompletenesstheorem:if the false is not provable, then that fact (that the false is not provable) is itself not provable.Nice, that is very satisfying.

OK. Nice.

Keep in mind that <>t (which I write also Dt) is the same as —[]f, whichis equivalent with "I am consistent", and Gödel's second theoremasserts: IfI am consistent then I cannot prove that I am consistent. Note thatthe "I"is a third person I. (The first person "I" considers his/herconsistencytrivial).Contraposition gives ~~[]<>t -> ~<>t, and this gives by above, []<>t -> []~t, which gives []<>t -> []f (as ~t = f, and ~f = t). OK?Ok!For the third one, starting from the first one again: <>t ->~[]<>t, Bycontraposition []<>t -> ~<>t , but ~<>t = []~t = [] f. OK?Ok! Thanks Bruno. My only problem now is the above.Tell me if you see that it was the modal version of Gödel's second incompleteness theorem. You might as an exercise show that it follows from Löb's theorem: [] ([] p -> p) -> [] p Two hints: 1) "~p" is the same as "p -> f", 2) replace p by f. OK? Löb's formula *is* the main axiom of the modal logic G.Alright, it's simple with the hints: [] ([] p -> p) -> [] p repalce p by f: [] ([] f -> f) -> [] f []f -> f = ~[]f: [](~[]f) -> []f contraposition: ~[]f -> ~(~[]f) Thanks!

You are welcome :) Bruno http://iridia.ulb.ac.be/~marchal/ -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at http://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/groups/opt_out.