But is there a form of math more powerful than algebra? Yes, Category/
Set Theory! Unlike algebra, Category/Set theory really *can* fully
reason about itself, since Sets/categories can contain other Sets/
Categories. Greg Cantor first explored these ideas in depth with his
transfinite arithmetic, and in fact it was later shown that the use of
transfinite induction can in theory bypass the Godel limitations. (See
Gerhard Gentzen)
>
>
>
> On Aug 27, 7:35 pm, Bruno Marchal <marc...@ulb.ac.be> wrote:
>
>>
>> Zermelo Fraenkel theory has full transfinite induction power, but is
>> still limited by Gödel's incompleteness. What Gentzen showed is that
>> you can prove the consistency of ARITHMETIC by a transfinite
>> induction
>> up to epsilon_0. This shows only that transfinite induction up to
>> epsilon_0 cannot be done in arithmetic.
>
> Yes. That's all I need for the purposes of my criticism of Bayes.
> SInce ZF theory has full transfinite induction power, it is more
> powerful than arithmetic.
>
> The analogy I was suggesting was:
>
> Arithmetic = Bayesian Inference
> Set Theory =Analogical Reasoning
This makes no sense for me.
Also, here arithmetic = Peano Arithmetic (the machine, or the formal
system).
Obviously (?, by Gödel) Arithmetic (arithmetical truth) is infinitely
larger that what you can prove in ZF theory.
Of course ZF proves much more arithmetical true statements than PA.
Interestingly enough, ZF and ZFC proves the same arithmetical truth.
(ZFC = ZF + axiom of choice);
And of course ZFK (ZF + existence of inaccessible cardinals) proves
much more arithmetical statements than ZF.
But all those theories proves only a tiny part of Arithmetical truth,
which escapes all axiomatizable theories.
>
> If the above match-up is valid, from the above (Set/Category more
> powerful than Arithmetic), it follows that analogical reasoning is
> more powerful than Bayesian Inference, and Bayes cannot be the
> foundation of rationality as many logicians claim.
>
> The above match-up is justified by (Brown, Porter), who shows that
> there's a close match-up between analogical reasoning and Category
> Theory. See:
>
> ‘"Category Theory: an abstract setting for analogy and
> comparison" (Brown, Porter)
>
> http://www.maths.bangor.ac.uk/research/ftp/cathom/05_10.pdf
>
> ‘Comparison’ and ‘Analogy’ are fundamental aspects of knowledge
> acquisition.
> We argue that one of the reasons for the usefulness and importance
> of Category Theory is that it gives an abstract mathematical setting
> for analogy and comparison, allowing an analysis of the process of
> abstracting
> and relating new concepts.’
>
> This shows that analogical reasoning is the deepest possible form of
> reasoning, and goes beyond Bayes.
I agree, but there are many things going beyond Bayes.
>
>
>> I agree with your critics on Bayesianism, because it is a good tool
>> but not a panacea, and it does not work for the sort of credibility
>> measure we need in artificial intelligence.
>
> The problem of priors in Bayesian inference is devastating. Simple
> priors only work for simple problems, and complexity priors are
> uncomputable. The deeper problem of different models cannot be
> solved by Bayesian inference at all:
Like all theorems, Bayes theorems can be used with many benefits on
some problems, and can generate total non sense when misapplied.
Bruno
That depends on what interpretation you are assigning to the
probability measure. Often it is "degree of belief", not a
prediction. But prediction is the gold-standard for understanding.
>
>
>> On the contrary, in Bohm's interpretation the particles are more like
>> real classical objects that have definite positions and momenta. What
>> you describe as Bohmian is more like quantum field theory in which
>> particles are just eigenstates of the momentum operator on the field.
>
> In Bohm, reality is separated into two different levels of
> organization, one for the particle level and one for the wave-level.
> But the wave-level is regarded by Bohm is being deeper, the particles
> are derivative. See:
>
> http://en.wikipedia.org/wiki/Implicate_and_Explicate_Order_according_to_David_Bohm
This is obviously written by an advocate of Bohm's philosophy - of
which his reformulation of Schrodinger's equation was on a small,
suggestive part. Note that Bohmian quantum mechanics implies that
everything is deterministic - only one sequence of events happens and
that sequence is strictly determined by the wave-function of the
universe and the initial conditions. Of course it doesn't account for
particle production and so is inconsistent with cosmogony and relativity.
Brent
>
> “In the enfolded [or implicate] order, space and time are no longer
> the dominant factors determining the relationships of dependence or
> independence of different elements. Rather, an entirely different sort
> of basic connection of elements is possible, from which our ordinary
> notions of space and time, along with those of separately existent
> material particles, are abstracted as forms derived from the deeper
> order. These ordinary notions in fact appear in what is called the
> "explicate" or "unfolded" order, which is a special and distinguished
> form contained within the general totality of all the implicate orders
> (Bohm, 1980, p. xv).”
>
> “In Bohm’s conception of order, then, primacy is given to the
> undivided whole, and the implicate order inherent within the whole,
> rather than to parts of the whole, such as particles, quantum states,
> and continua.”
>
>
>> I'd say analogies are fuzzy associations. Bayesian inference applies
>> equally to fuzzy associations as well as fuzzy causal relations - it's
>> just math. Causal relations are generally of more interest than other
>> relations because they point to ways in which things can be changed.
>> With apologies to Marx, "The object of inference is not to explain the
>> world but to change it."
>
> Associations are causal relations. But true explanation is more than
> just causal relations, Bayes deals only with prediction of causal
> relations..
Bayes deals with whatever you put a probability measure on. Most
often it is cited as applying to degrees of belief, which is what
Cox's theorem is about.
>A more important component of explanation is
> categorization. See:
>
> http://en.wikipedia.org/wiki/Categorization
>
> "Categorization is the process in which ideas and objects are
> recognized, differentiated and understood. Categorization implies that
> objects are grouped into categories, usually for some specific
> purpose."
>
> Analogies are concerned with Categorization, and thus go beyond mere
> prediction. See ‘Analogies as Categorization’ (Atkins)
> :
> http://www.compadre.org/PER/document/ServeFile.cfm?DocID=186&ID=4726
>
> “I provide evidence that generated analogies are assertions of
> categorization, and the
> base of an analogy is the constructed prototype of an ad hoc category”
One may invent analogies and categories, but how do you know they are
not just arbitrary manipulation of symbols unless you can predict
something from them. This seems to me to be an appeal to mysticism
(of which Bohm would approve) in which "understanding" becomes a
mystical inner feeling unrelated to action and consequences.
Brent
>> Actually Bayesian inference gives a precise and quatitative meaning to
>> Occam's razor in selecting between models.
>>
>> http://quasar.as.utexas.edu/papers/ockham.pdf
>>
>>
>>
>
> The formal definitions of Occam’s razor are uncomputable. Remember,
> the theory of Bayesian reasoning is *itself* a scientific model, so
> differences of opinion about Bayesian models will result in mutually
> incompatible science. That’s why Bayes has serious problems. (see
> below for more on this point)
>
And analogical reasoning is computable and doesn't produce any
differences of opinion??
>
>
>> And beliefs do not converge, even in probability - compare Islam and
>> Judaism. Why would any correct theory of degrees of belief suppose
>> that finite data should remove all doubt?
>>
>
>
> So how did people come to believe things like Islam and Judaism in
> the first place? (the beliefs PRIOR to collecting evidence) Bayes
> can’t tell you *what* to believe, it can only tell you how your
> beliefs should *change* with new evidence. The fact that you are free
> to believe anything to start with shows that Bayes has major
> problems.
>
The only reasons analogical reasoning seems better to you is that it's a
vague and ill defined method that encompasses anything you want it to.
You are always free to believe anything. Of course Bayesian inference
doesn't solve all problems - but at least it solves some of them.
> Stathis once pointed on this list that crazy people can actually still
> perform axiomatic reasoning very well, and invent all sorts of
> elaborate justifications, the problem is their priors, not their
> reasoning; so if you try to use Bayes as the entire basis of your
> logic, you’re crazy ;)
>
Axiomatic reasoning =/= probabilistic reasoning. Try basing all your
reasoning on analogies.
Brent
>
>
>
>
>>> http://en.wikipedia.org/wiki/Implicate_and_Explicate_Order_according_...
>>>
>> This is obviously written by an advocate of Bohm's philosophy - of
>> which his reformulation of Schrodinger's equation was on a small,
>> suggestive part. Note that Bohmian quantum mechanics implies that
>> everything is deterministic - only one sequence of events happens and
>> that sequence is strictly determined by the wave-function of the
>> universe and the initial conditions. Of course it doesn't account for
>> particle production and so is inconsistent with cosmogony and relativity.
>>
>> Brent
>>
>
> This is not a failing of the Bohemian interpretation, because *every*
> interpretation of quantum mechanics suffers from it ; no one has yet
> succeed in producing a consistent quantum field theory for the simple
> reason that general relatively contradicts quantum mechanics.
>
But Bohmian QM isn't even compatible with special relativity - which
quantum field theory is. QFT handles particle production just fine.
>
>
>>> Associations are causal relations. But true explanation is more than
>>> just causal relations, Bayes deals only with prediction of causal
>>> relations..
>>>
>> Bayes deals with whatever you put a probability measure on. Most
>> often it is cited as applying to degrees of belief, which is what
>> Cox's theorem is about.
>>
>
> But what justifies Cox's theorem?
Read it. It's an axiomatic deduction from some axioms about what
constitutes a rational adjust of belief based on data.
> Ultimately, to try to justify math
> you can’t use ‘degrees of belief’, but have to fall back on deep math
> like Set/Categoy theory (since Sets/Categories are the foundation of
> mathematics).
How do you justify set theory? By appeal to axioms that seem
intuitively true, with some adjustments to make the deductions
interesting. For example set theory says {{}}=/={} even though most
people find {{}}={} intuitive, but it would be hard to build things on
the empty set with the latter as an axiom.
> This shows that Bayes can’t be foundational
>
I never said it was. Although the fact that it has not been used in an
axiomatic foundation of math doesn't prove that it couldn't be.
>
>> One may invent analogies and categories, but how do you know they are
>> not just arbitrary manipulation of symbols unless you can predict
>> something from them. This seems to me to be an appeal to mysticism
>> (of which Bohm would approve) in which "understanding" becomes a
>> mystical inner feeling unrelated to action and consequences.
>>
>> Brent-
>>
>
> Pure mathematics is a science which is not based on prediction,
> instead it is about finding structural relationships between different
> concepts (integrating different pieces of knowledge). Categories form
> the basis for knowledge representation and pure mathematics, which is
> prior to any sort of prediction. Category/Set Theory is utterly
> precise science, the opposite of mysticism.
>
But it's not based on analogical rules of inference either.
> Bohm's interpretation of QM is utterly precise and was published in a
> scientific journal (Phys. Rev, 1952). In the more than 50 years
> since, no technical rebuttal has yet been found, and it is fully
> consistent with all predictions of standard QM.
In fact it's mathematically equivalent to Schrodinger's equation with
just a different interpetation.
> In fact the Bohm
> interpretation is the only realist interpretation offering a clear
> picture of what’s going on – other interpretations such as Bohr deny
> that there’s an objective reality at all at the microscopic level,
> bring in vague ideas like the importance of ‘consciousness’ or
> ‘observers’ and postulate mysterious ‘wave functions collapses, or
> reference a fantastical ‘multiverse’ of unobservables, disconnected
> from actual concrete reality. Bohm is the *only* non-mystical
> interpretation!
>
It is mystical in that it assumes holism, so that the wave-function of
the universe is instantaneously changed by an interaction anywhere.
> In fact from;
> http://en.wikipedia.org/wiki/Implicate_and_Explicate_Order_according_to_David_Bohm
>
> "Bohm’s paradigm is inherently antithetical to reductionism, in most
> forms, and accordingly can be regarded as a form of ontological
> holism."
>
> Since Bohm's views are non-reductionist and still perfectly
> consistent, this casts serious doubt on the entire reductionist world-
> view on which Bayesian reasoning is based.
I don't know why the mere existence of some consistent holistic math
model - which cannot account for observed particle production - should
count as evidence against a reductionist world view.
Brent
> Another exmaple would be dream
> states, you could reason probalistically in your sleep, but without
> the correct priors, your dreams will still be largely incoherent.
>
There's a huge difference between incoherent and incorrect.
> Don't get me wrong, I'm sure Bayes is very powerful- I just don't
> think it's the be-all and end-all.
>
>
>> Try basing all your
>> reasoning on analogies.
>>
>> Brent
>>
>
> I do. I think Bayes is just a special case of analogical reasoning ;)
Then you can say analogical reasoning is just a special case of
reasoning. Which then proves that reasoning is more fundamental than
analogical reasoning. Then will you claim to have destroyed analogical
reasoning. ??
Brent
Cox showed it is a rational ideal for updating one's beliefs based on
new evidence. Has anyone shown that analogical reasoning is optimum in
any sense?
> What I'm 'destroying'
> is that claim. And I've done that. But of course Bayes is still very
> useful and powerful.
>
>
>
>
>>> Since Bohm's views are non-reductionist and still perfectly
>>> consistent, this casts serious doubt on the entire reductionist world-
>>> view on which Bayesian reasoning is based.
>>>
>> I don't know why the mere existence of some consistent holistic math
>> model - which cannot account for observed particle production - should
>> count as evidence against a reductionist world view.
>>
>>
>
> Because if the reductionist world-view is the correct one, the non-
> reductionist world view should have serious inconsistencies, the fact
> that there's not yet a conclusive technical rebuttal of Bohm counts as
> evidence against reductionism.
What's a technical rebuttal if particle production isn't?? Failure to
predict what is observed is usually considered a severe defect in physics.
Also, note that there is no reason that there couldn't be both holistic
and reductionist accounts of the same thing.
Brent
> Bayes can't.
But obviously reasoning, per se, is at least as powerful as analogical
reasoning, since it includes analogical as well as axiomatic,
probabilistic, metaphorical, intuitionist, etc. My point is that you
have not given any definition of analogical reasoning. By leaving it
vague and undefined you allow yourself to alternately identify every
kind of reasoning as analogical - or a special case of analogical.
Which isn't wrong - but it doesn't have much content either.
Brent
>
>
>
> On Aug 29, 2:36 am, Bruno Marchal <marc...@ulb.ac.be> wrote:
>
>>
>> Obviously (?, by Gödel) Arithmetic (arithmetical truth) is infinitely
>> larger that what you can prove in ZF theory.
>
> Godel’s theorem doesn’t mean that anything is *absolutely*
> undecidable;
OK.
Computability is absolute,
Provability is relative.
> it just means that not all truths can captured by
> *axiomatic* methods; but we can always use mathematical intuition (non
> axiomatic methods) to decide the truth of anything can't we?.
In principle. "No ignorabimus" as Hilbert said. Yet no machine or
formal systems can prove propositions too much complex relatively to
themselves, and there is a sense to say that some proposition are
undecidable in some absolute way, relative to themselves.
>
> http://en.wikipedia.org/wiki/Gödel's_incompleteness_theorems
>
> "The TRUE but unprovable statement referred to by the theorem is often
> referred to as “the Gödel sentence” for the theory. "
>
> The sentence is unprovable within the system but TRUE. How do we know
> it is true? Mathematical intuition.
Not really. The process of finding out its own Gödel sentence is
mechanical. Machines can guess or infer their own consistency, for
example. In AUDA intuition appears with the modality having "& p" in
the definition (Bp & p, Bp & Dp & p).
Those can be related with Bergsonian time, intuitionistic logic,
Plotinus universal soul, and sensible matter.
>
> So to find a math technique powerful enough to decide Godel
> sentences ,
This already exists. The diagonilization is constructive. Gödel's
proof is constructive. That is what Penrose and Lucas are missing
(notably).
> we look for a reasoning technique which is non-axiomatic,
This is the case for the "& p" modalities. They are provably
necessarily non axiomatisable. They lead to the frst person, which,
solipstically, does separate truth and provability.
> by asking which math structures are related to which possible
> reasoning techniques. So we find;
>
> Bayesian reasoning (related to) functions/relations
> Analogical reasoning (related to) categories/sets
Those are easily axiomatized.
I see the relation "analogy-category", but sets and functions are
together, and not analogical imo.
I don't see at all the link between Bayes and functions/relations.
Actually, function/relations are the arrows in a category.
>
> Then we note that math structures can be arranged in a hierarchy, for
> instance natural numbers are lower down the hierarchy than real
> numbers, because real numbers are a higher-order infinity. So we can
> use this hierarchy to compare the relative power of epistemological
> techniques. Since:
>
> Functions/relations <<<< categories/sets
You may use some toposes (cartesian close category with a sub-object
classifier). Those are "mathematical" mathematicians. But assuming
comp, does not let you much choice on which topos you can choose. It
has to be related to the S4Grz epistemic logic (in the "ideal" case).
>
> (Functions are not as general/abstract as sets/categories; they are
> lower down in the math structure hierarchy)
>
> Bayes <<<<<< Analogical reasoning
>
> So, analogical reasoning must be the stronger technique. And indeed,
> since analogical reasoning is related to sets/categories (the highest
> order of math) it must the strongest technique. So we can determine
> the truth of Godel sentences by relying on mathematical intuition
> (which from the above must be equivalent to analogical reasoning).
> And nothing is really undecidable.
The truth of Gödel sentences are formally trivial. That is why
consistency is a nice cousin of consciousness. It can be shown to be
true easily by the system, and directly (in few steps), yet remains
unprovable by the system, not unlike the fact that we can be quasi
directly conscious, yet cannot prove it. Turing already exploited this
in his "system of logic based on ordinal" (his thesis with Church).
Bruno
> Bohm's interpretation of QM is utterly precise and was published in a
> scientific journal (Phys. Rev, 1952). In the more than 50 years
> since, no technical rebuttal has yet been found, and it is fully
> consistent with all predictions of standard QM. In fact the Bohm
> interpretation is the only realist interpretation offering a clear
> picture of what’s going on – other interpretations such as Bohr deny
> that there’s an objective reality at all at the microscopic level,
> bring in vague ideas like the importance of ‘consciousness’ or
> ‘observers’ and postulate mysterious ‘wave functions collapses, or
> reference a fantastical ‘multiverse’ of unobservables, disconnected
> from actual concrete reality. Bohm is the *only* non-mystical
> interpretation!
Bohm's QM is a variant of QM, which keeps the Everett many worlds, but
use a very unclear theory of mind, and a very unclear notion of
particle to make one hidden Everett branch of reality "more real" than
the other, and this by reintroducing non-locality in the picture, and
many zombies in the universal wave.
Bruno
> This is the case for the "& p" modalities. They are provably
> necessarily non axiomatisable. They lead to the frst person, which,
> solipstically, does separate truth and provability.
I mean does NOT separate truth and provability (like solipsist).
Sorry,
Bruno
This does not make sense.
>
>
> In ‘I Am a Strange Loop’, Hofstadter argues that the procedure for the
> determining the truth of Godel sentences is actually a form of
> analogical reasoning. (Chapters 10-12)
>
> (page 148)
>
> ‘by virtue of Godel’s subtle new code, which systematically mapped
> strings of symbols onto numbers and vice versa, many formulas could be
> read on a second level. The first level of meaning obtained via the
> standard mapping, was always about numbers, just as Russell claimed,
> but the second level of meaning, using Godel’s newly revealed mapping…
> was about formulas’
> …
> (page 158)
>
> ‘all meaning is mapping mediated, which is to say, all meaning comes
> from analogies’
This can make sense. Analogies are then seen as a generalization of
morphism, which is the key notion of category theory.
>
>
>
>
>>
>>> Bayesian reasoning (related to) functions/relations
>>> Analogical reasoning (related to) categories/sets
>>
>> Those are easily axiomatized.
>> I see the relation "analogy-category", but sets and functions are
>> together, and not analogical imo.
>> I don't see at all the link between Bayes and functions/relations.
>> Actually, function/relations are the arrows in a category.
>
> See what I said in my first post this thread. The Bayes theorem is
> the central formula for statistical inference. Statistics in effect
> is about correlated variables. Functions/Relations are just the
> abstract (ideal) version of this where the correlations are perfect
> instead of fuzzy (functions/relations map the elements of two sets).
> That’s why I say that Bayesian inference bears a strong ‘family
> resemblance’ to functions/relations.
>
> You agreed that analogies bear a strong ‘family resemblance’ to
> categories.
>
> Category theory *includes* the arrows. So if the arrows are the
> functions and relations (which I argued bears a strong family
> resemblance to Bayesian inference), and the categories (which you
> agreed bear a family resemblance to analogies) are primary, then this
> proves my point, Bayesian inferences are merely special cases of
> analogies, confirming that analogical reasoning is primary.
You may develop. My feeling is that to compare category theory and
Bayesian inference, is like comparing astronomy and fishing. They
serve different purposes. Do you know Dempster Shafer theory of
evidence? This seems to me addressing aptly the weakness of Bayesian
inference.
Bruno
In Bohm, the wave is not an abstract field, it plays a concrete role
in the determination of the position of the particles I can observed.
It is not a question of interpretation, it follows form the fact that
the wave guides the particles by simulating completely the parallel
branches. And in those branches the person acts exactly like believing
they are made of particles "like us".
How could we know that we belong to the branch with particles? We need
already to abandon CTM here.
>
> The Bohm interpretation is actually the clearest of all
> interpretations.
It is not an interpretation. It is another theory. It is more sensical
than Copenhagen, but is a regression with respect to CTM, which
already explains why "observable reality" emerges from infinities of
computations.
> It does away with the enormous multiverse edifice of
> unobservables,
Nature has always contained many unobservable things, multiplied in
huge quantities, be it galaxies, before Hubble, or water molecules. It
is the basic motto of the "everything" idea that multiplying entities
can make our theories conceptually simpler.
> whilst at the same time maintaining a realist picture
> of reality (agrees that wave function is real and doesn’t collapse,
> whilst placing a single concrete reality on a different level).
It is a form of cosmo-solipism. We always want to be unique, but that
is coquetry.
>
> You may like to look the volume (‘Quantum Implications’, B.J.Hiley,
> F.David Peat) for examples of how the Bohm interpretation makes
> problems which are unclear with other interpreations, very clear with
> Bohm. Since Bohm is non-reductionist and no conclusive rebuttals have
> been found in over 50 years, it counts as evidence against the
> reductionist world-view (and thus also evidence against Bayes).
>
> Brent did make the point that it has trouble with field theory, but
> this problem is a feature of other interpretations also. Brent also
> criticised the non-locality, but again, this problem is a feature of
> all other interpretations also.
I disagree. Everett restores locality, as he explains himself. Deutsch
and Hayden wrote a paper explaining rather well how locality is
completely restored in the many-worlds view.
And as I said, comp alone entails the many "worlds" (or many
dreams, ...). That part of the SWE confirms comp. If I remember well,
Bohm intuited this and made some case against the computationalist
hypothesis.
Bruno
On Aug 30, 7:23 pm, Bruno Marchal <marc...@ulb.ac.be> wrote:On 30 Aug 2009, at 07:06, marc.geddes wrote:It’s true that there is no wave function collapse in Bohm, so it usesthe same math as Everett. But Bohm does not interpret the wavefunction in ‘many world’ terms, in Bohm the wave function doesn’trepresent concrete reality, its just an abstract field – the concretereality is the particles, which are on a separate level of reality, sothere are no ‘zombies’ in the wave function.In Bohm, the wave is not an abstract field, it plays a concrete rolein the determination of the position of the particles I can observed.It is not a question of interpretation, it follows form the fact thatthe wave guides the particles by simulating completely the parallelbranches. And in those branches the person acts exactly like believingthey are made of particles "like us".How could we know that we belong to the branch with particles? We needalready to abandon CTM here.
Yes, in Bohm the wave is 'real' , but to interpret the wave as
actually referring to ordinary concrete things is already to
presuppose 'many worlds' ;
reality has two levels, so really there's
two different definitions of 'real' in Bohm.
There are no 'people' in
the wave, its a more abstrast entity than ordinary concrete reality.
Brent did make the point that it has trouble with field theory, butthis problem is a feature of other interpretations also. Brent alsocriticised the non-locality, but again, this problem is a feature ofall other interpretations also.I disagree. Everett restores locality, as he explains himself. Deutschand Hayden wrote a paper explaining rather well how locality iscompletely restored in the many-worlds view.And as I said, comp alone entails the many "worlds" (or manydreams, ...). That part of the SWE confirms comp. If I remember well,Bohm intuited this and made some case against the computationalisthypothesis.Bruno
If MWI does eliminate non-locality, that would be a strong point in
its favor,
but is there any conclusive paper demonstrating that its
done this? I have not heard of one - I assume the Deutsch/Hayden
paper is just their attempt to restore locality which does not
succeed.
>
>
>
> On Aug 30, 7:05 pm, Bruno Marchal <marc...@ulb.ac.be> wrote:
>>
>> This does not make sense.
>
> You said;
>
>> The truth of Gödel sentences are formally trivial.
>> The process of finding out its own Gödel sentence is
> mechanical.
>> The diagonilization is constructive. Gödel's
> proof is constructive. That is what Penrose and Lucas are missing
> (notably).
>
> This contradicts Godel. The truth of any particular Godel sentence
> cannot be formally determined from within the given particular formal
> system - surely that's what Godel says?
Not at all. Most theories can formally determined their Gödel
sentences, and even bet on them.
They can use them to transform themselves into more powerful, with
respect to probability, machines, inheriting new Gödel sentences, and
they can iterate this in the constructive transfinite. A very nice
book is the "inexhaustibility" by Torkel Franzen.
Machine can determined their Gödel sentences. They cannot prove them,
but proving is not the only way to know the truth of a proposition.
The fact that G* is decidable shows that a very big set of unprovable
but true sentences can be find by the self-infering machine. The
machine can prove that if those sentences are true, she cannot prove
them, and she can know, every day, that they don't have a proof of
them. They can instinctively believe in some of them, and they can be
aware of some necessity of believing in some other lately.
>
> The points are addressed in ‘Shadows of The Mind’ (Section 2.6,
> Q6).
Hmm...
>
> The point of Penrose/Lucs is that you can only formally determine the
> Godel sentence of a given system from *outside* that system.
The cute thing is that you can find them by inside. You just can prove
them, unless you take them as new axiom, but then you are another
machine and get some new Godel sentences. Machines can infer that some
arithmetical sentences are "interesting question only". The machine
can see the mystery, when she looks deep enough herself.
I would say it is very well known, by all logicians, that Penrose and
Lucas reasoning are non valid. A good recent book is Torkel Franzen
"Use and abuse of Gödel's theorem".
Another "classic" is Judson Webb's book.
Ten years before Gödel (and thus 16 years before Church, Turing, ...)
Emil Post has dicovered Church thesis, its consequences in term of
absolutely insoluble problem and relatively undecidable sentences, and
the Gödelian argument against mechanism, and the main error in those
type of argument. Judson Webb has seen the double razor edge feature
of such argument. If you make them rigorous, they flash back and you
help the machines to make their points.
> We
> cannot determine *our own* Godel sentences formally,
We can, and this at each level of substitution we would choose. But
higher third person level exists also (higher than the substitution
level) and are close to philosophical paradoxes.
AUDA comes from the fact that ,not only machine can determined and
study their Gödel sentences, but they can study how those sentences
determined different geometries according to the points of view which
is taken (cf the eight arithmetical hypostases in AUDA).
Bruno
Not at all. Most theories can formally determined their Gödel
sentences, and even bet on them.
They can use them to transform themselves into more powerful, with
respect to probability, machines, inheriting new Gödel sentences, and
they can iterate this in the constructive transfinite. A very nice
book is the "inexhaustibility" by Torkel Franzen.
Machine can determined their Gödel sentences. They cannot prove them,
but proving is not the only way to know the truth of a proposition.
The fact that G* is decidable shows that a very big set of unprovable
but true sentences can be find by the self-infering machine.
Brent
On Aug 31, 4:19 am, Bruno Marchal <marc...@ulb.ac.be> wrote:On 30 Aug 2009, at 10:12, marc.geddes wrote:But look at this. I decide to do the following experience. I preparean electron so that it is in state up+down. I measure it in the base{up, down}, and I decide to take holiday in the North if I find it up,and to the south, if I find it down.Not only that. I decide to go, after the holiday, to the amnesiacenter where all my memories, from the state of the electron toeverything which follows, except my feeling about how much I enjoy theholliday. And I am asked to answer by yes or no to the question "didyou enjoy your holiday. Then, thanks to the amnesia my yes+no stateswill be used In this way. I interfere with myself, and what willfollow in the new branch where I have fuse with myself, my, and your,future is determined by my contentment qualia, in the two branches ofthe waves.
This assumes that qualia are completely determined by the wave
function, which (since Bohm is non-reductionist) I'm sure he'd
dispute. The wave function only predicts physical states, it does not
neccesserily completely determine higher-level properties such qualia
(although of course qualia depends on low-level physics). If the wave
function DID completely determine the qualia, your example would
indeed contradict Bohm - but Bohm already admits he's non-
reductionist.
A weakness of MWI is that it does not describe the reality we actually
see - additional steps are needed to convert wave function to human
observables - Bohm makes this clear, MWI just disguises it. Even in
MWI, additional unexpected steps (Born probabilities derivation etc)
are needed to convert wave function to what we actually observe.
But MWI has the same problem, it just states it in different terms, in
MWI all worlds exist, but which one will we actually observe? In
Bohm, only one world is there, but which of the paths in the wave
function is it?
>
>
>
> On Aug 31, 8:10 pm, Bruno Marchal <marc...@ulb.ac.be> wrote:
>> On 31 Aug 2009, at 03:50, marc.geddes wrote:
>
>>
>>> This assumes that qualia are completely determined by the wave
>>> function, which (since Bohm is non-reductionist) I'm sure he'd
>>> dispute. The wave function only predicts physical states, it does
>>> not
>>> neccesserily completely determine higher-level properties such
>>> qualia
>>> (although of course qualia depends on low-level physics). If the
>>> wave
>>> function DID completely determine the qualia, your example would
>>> indeed contradict Bohm - but Bohm already admits he's non-
>>> reductionist.
>>
>> Well, meaning that he is non computationalist. No problem, in free
>> country.
>
> I don't know - does non-reductionist mean non-computationalist? I
> hope not. Non-reductionist just means not all the high-level
> properties of a system are determined by the lower-level properties.
> I'm assuming its still all computational.
>
It has to be non-comp. If not he has to accept that my doppelganger
has experience like you and me, guven that the branch implements the
paralel computation. Bohm is non sensical with comp. Everett is really
just QM + comp, and indeed, it is comp alone (assuming QM is correct).
Now, machanism, after Emil Post-Gödel & Co., can be explained to be
the less reductionist theory possible, as I argue often with John.
>
>>
>>
>>
>>> A weakness of MWI is that it does not describe the reality we
>>> actually
>>> see - additional steps are needed to convert wave function to human
>>> observables - Bohm makes this clear, MWI just disguises it. Even in
>>> MWI, additional unexpected steps (Born probabilities derivation etc)
>>> are needed to convert wave function to what we actually observe.
>>
>> I am not sure. Bohm has to use an unknwown and unspecified (but very
>> vaguely) theory of mind.
>> The MWI has to use only comp (a modern version of a very old theory
>> of
>> mind).
>> (Then I point on the fact that if we take comp seriously the SWE has
>> to be justified from numbers only, but that is nice because it points
>> to a further simplification of the theory).
>
> But the wave function does not describe the reality we actually
> observe -
> that needs additional steps. Bohm just makes his explicit,
> but MWI has them too (needs an additional step to convert wave
> function to Born probabilities, MWI itself doesn't explain why for
> instance we aren't aware of the other branches and don't see
> superpositional states - needs additional theory of mind of some sort
> too).
Everett insists and other have make this more precise that the
probabilities emerge as first person constructs, and comp juutsifies
those first person construct, without assuming QM.
Everett QM confirms comp, up to now.
Everett explains why we don't feel the split, why we cannot see or
interact with the other branches, and provides the correct probability
(quesi directly with Gleason theorem + frequentist proba).
And his the most parcimonious, à-la-Occam theory of nature.
Bohm needs non-comp, and an utterly weird theory of matter, with
hidden particles having necessarily unknown initial condition. All
that for transforming my quantum doppelganger into zombie.
Bohm-De Broglie is a sane reaction in front of Bohr-heisenberg fuzzy
irrealism, or von Neumann-Wigner dualism, but has been made useless
with Everett discovery that we really don't need a wave collapse. You
can derive from the SWE only, why people appears and develop beliefs
in classical reality.
The only (strong) critics you can do to Everett, is that he iis using
comp, and UDA+MGA shows that if QM is empirically correct, then QM has
to be derived purely arithmetically.
Comp makes elemntary Arithmetic the theory of Everything.
>
>
>
>
>>
>>> But MWI has the same problem, it just states it in different
>>> terms, in
>>> MWI all worlds exist, but which one will we actually observe? In
>>> Bohm, only one world is there, but which of the paths in the wave
>>> function is it?
>>
>> Not at all. The question "which world" is reduced to the question
>> "why
>> W" or "Why M" in an WM self-duplication experiment, or to the child
>> question "why do I feel to be me and not my brother". Comp justifies
>> why universal machine have to ask such question, and why they cannot
>> answer them, and why they can explain that such question have no
>> answer when assuming comp.
>> Bohm has to make special an observable (position), to threat away
>> locality, to introduce hidden variables, and a supplementary
>> equation,
>> which describe necessarily hidden things.
>>
>> Bruno
>>
>
> See above, MWI needs supplementary theories too to convert wave
> function into observables (things like procedure for deriving Born
> probabilities etc), in practice position needs to be singled out to
> make measurements.
Not at all. This is the point made clear by Zurek, and the decoherence
theory. Everett theory does not need to sibgle out a base against the
other. The position base singles out itself.
>
> Main problem with Bohm is the non-locality,
and non computationalism. And this makes its theory more reductionist
than computationalism.
> but on the other hand its
> picture of the world is much clearer
I have work on comp to understand what is matter, because the naïve
conception leads to many difficulties, both with QM, but also with
comp, and even by itself (try to define matter without matter, for
example).
The reappartion of particles would be a problem for comp, and a
problem for those who does not believe in particles.
> and doesn't require huge
> quantities of unobservables (alternative universes).
This is a quality of the theory. Not only because it confrims the comp
many dreams, but because a unique physical universe would have been
arguably an ontological aberration.
In any case, Everett is a step by physicist toward comp, and in comp,
at the ontic level, we need the least ontology possible: numbers (with
+ and *). All the rest can be explained, and *is* explained by the
discurses of self-observing universal machine.
> I'd rate the two
> interpretations about equally good (50-50 toss up). Will read your
> links on locality and think over the example more.
Don't hesitate to dig on those issues. No doubt that Bohm provides an
interesting and indeed coherent non local and non computaionalist
theory.
But it looks for me as a sophisticate attempt to dodge the mind-body
problem, and to make very complex, with his non covariant potential,
what is really much more simple (the SWE).
Bruno