2009/8/10 Bruno Marchal <marc...@ulb.ac.be>:
Bruno, I'm broadly in agreement with your comments, and merely
re-emphasise a few points below on which I'm being a stickler. Also,
I have some further comments and questions on step 8.
>> In this light
>> it becomes self-evident that any and all explanatory entities -
>> physical, computational, or whatever - are severely restricted to the
>> domain of epistemology.
> I don't see why. I would not put arithmetic in epistemology, or only
> in a very large sense of epistemology, the epistemology of the 0-
> person views!. It seems clearer to accept them ontologically like in
> the usual practice of math. Could be only a vocabulary problem here.
Yes, I normally wouldn't dispute this point, but but I'm being a
stickler here. In the strictest sense the ontological equivalence of
anything whatsoever to the indexical OFP can only be an assumption -
albeit one that might be justifiable in the case of the best theory.
Beyond this, that the unique qualitative nature of the OFP *is* as it
appears, is in principle outside the scope of explanation itself.
>> IOW - as Bruno says above - they are
>> theoretical constructions.
> Yes, but this does not mean those construction does not refer to
> something real independently of us, and this is what I assume for
I agree, as above that it is the whole point of our endeavours to say
that the construction *refers* to something real. But I think perhaps
that the something thus referenced is not best characterised as being
real *independently* of us, but rather *constitutive* of us and our
(most general) environment.
> Even if the whole existence get annihilated, 17 would still be
I understand that it is justifiable to take this as your point of
departure and don't really wish to make an argumentative point out of
it. Nonetheless, in passing, perhaps I have a more radical intuition
of annihilation than you. One can waste a lot of breath speculating
on 'nothing' because, strictly I guess, there can be nothing at all it
can refer to. I could demonstrate this, given infinite time, simply
by flatly rejecting *any* survivor of such annihilation that you or
anyone cared to propose, to the crack of doom. On this basis, even
'17 is prime' is a goner.
>> So far so obvious. But - as has again been recognised immemorially -
>> solipsism is a dead-end and hence we seek a theory to capture the
>> relation between the OFP and its environment. But immediately we are
>> faced with the notorious 'explanatory gap', and it seems to me that
>> its most precise expression is in the gap between ontology and
>> epistemology. Indeed, what conceivable strategy could raise these
>> theoretical constructions - to which the OFP uniquely lends existence
>> - to the ontological certainty of their host? Is there a coherent way
>> to conceive what it could mean to *be* a theoretical entity (as
>> opposed to postulating or observing one)?
> It is the point of saying "yes" to the doctor. You don't say yes
> because the new brain is a good modelisation of your brain, but
> because you bet it will enact yourself completely, relatively to the
Yes indeed, this is my point. There is no way to *conceive* in
advance what it would mean to *be* such an enactment (i.e. to be
*sure*) so you can only bet that saying yes will not affect the state
of the indexical OFP.
> You may confuse the reality of number, and the reality of machine/
> theories talking about those numbers. Numbers are not viewed as
> theoretical construction. The theoretical construction are our
> theories on the numbers. It simplifies things.
I agree that this assumption simplifies things, and as you say it is
one shared by all mathematicians. But again, in the final analysis,
numbers can only be 'viewed' as ontologically real, not *known* to be.
But this is true of any assumption whatever, and I freely concede
your points about the simplicity of the assumptions in the case of
> All theories demands faith, but the faith needed for understanding
> that 17 is prime is not comparable to the act of faith needed to say
> yes to the doctor.
>> It's no use appealing to
>> notions of 'what it's like to be a brain' - nor what it's like to be a
>> COMP-quale - because we can never say that it is 'like anything to be'
>> the stuff of epistemology.
> Assuming comp we can still say that it is like you feel right now.
> Only zombie cannot understand, but if they are good zombie, they will
> have no problem to fake that they understand.
Yes, *assuming* comp. We cannot *know* what it is like to be a
comp-quale, but we may have sufficient faith to bet that it's like
'what you feel right now'.
>> Hence we must see our theorising and
>> observing - in physical, computational, or whatever terms - *in
>> relation* to ontological certainty, not as constitutive of it.
> That's right.
> I thought this was obvious.
You may have heard the following story. A professor of mathematics
enters the lecture room with a sheaf of papers and writes a complex
theorem on the blackboard. He turns to the students and says "ladies
and gentlemen, this of course is obvious". He then shuffles his
papers, looks at the board again and continues more doubtfully "at
least, I think it is obvious". Then he stares fixedly at the board
for ten minutes without speaking, looking increasingly uncomfortable.
Finally, he rubs out the theorem and leaves the room. The students
are nonplussed, but remain in their seats. Thirty minutes later, the
professor re-enters the room, looking disheveled but happy. He writes
exactly the same theorem on the blackboard with a flourish, turns to
his audience and announces triumphantly "ladies and gentlemen, I was
right - it IS obvious!"
>> Rather, they stand in some theoretical
>> relation to RITSIAR, but strictly on the epistemological side of the
>> explanatory gap. They are 'real as far as theory takes us', or if
>> further jargon is unavoidable: RAFATTU.
> Well frankly this will depend of the first "T" of RAFATTU. It depends
> of the theory.
> With the comp theory, quarks, electrons, planet and galaxies are not
> ontologically real.
> With string theory, they may be real.
Yes, real in the relative sense we have been discussing.
>> My argument against the *physical* instantiation of a computational
>> mind (i.e. in any non-eliminative sense) rests on the claim that the
>> very arbitrariness of possible physical instantiations of a given
>> computation (cf Hofstadter) violates the criterion of direct
>> supervention on *specific* physical entities and relations from which
>> a class of emergent phenomena inherits physical - as opposed to merely
>> mental (and hence egregiously question-begging) - stability.
> I think that this what the movie graph argument makes necessary.
Good, I'm glad we agree.
>> Naturally, all this is per physics as ordinarily understood.
>> Tolerating such a violation is tantamount to accepting (and this is
>> notoriously claimed by Hofstadter et al) that *any* arbitrarily
>> assembled set of physical entities deemed to be in the required
>> 'functional' relation (e.g. - famously - in an anthill) necessarily
>> stabilises exactly the same 'mental state'. AFAICS this is by itself
>> quite sufficient to reveal such a 'mind' as intrinsically unphysical -
>> and a fortiori un-RITSIAR.
> Hmm... things are more subtle, but in a first approximation this can
> be useful.
Remember, I mean 'unphysical' in terms of standard physical theory.
By un-RITSIAR, in this instance, I mean that in these strictly
physical terms (i.e. without comp) such a mind doesn't even exist -
hence 'a fortiori'.
>> My argument assumes, however, that - per physicalism - a running
>> computation (as opposed to its specification)
> It is important to distinguish a program (immaterial static object)
> and a computation (an immaterial "dynamic" object, which can be finite
> or infinite, but is best handled when accepting it is infinite,
> because in that case a dynamic can be defined by a function from N to
> anything: it is a sequence of things). If not, people get troubled by
> the existence of running computation in platonia/arithmetical truth.
Ah, but my argument attempts to distinguish a computation (immaterial
dynamic object) and an implementation of a computation (material
dynamic process) - again, per standard physical theory - as a
refutation of standard comp *in these strictly physical terms*. My
point is, that per physicalism, a computation must be implemented in
some physical mechanism in order to have any real - i.e. physical -
effects (at least this was true the last time I did any programming).
Hence the existence of 'immaterial objects' in this case is simply
irrelevant to any effects that would be strictly justifiable as
ontologically real, per physicalism. Consequently, I agree that the
reversal of ontological primacy you stipulate is necessary to save
Your argument however seems to be based not on the physical
implementation but the 'immaterial' computation to which it is
postulated - per standard comp - to be equivalent. Is this right?
(More on this below.)
>> necessarily requires
>> *some* physical activity to transform inputs to outputs (e.g. in terms
>> of logic gates). Step 8, however, seems to take a step beyond this by
>> proposing that a running computation can take the form of (as opposed
>> to merely being described by) a machine *state*: i.e. without the
>> requirement of activity.
> No, activity is required. But activity is just a function from N to
> set of states. The movie graph show that a machine cannot distinguish
> physical activity from such an arithmetical activity. A computation is
> an infinite set of numbers such that there is a universal number
> generating that sequence.
When you say that "activity is just a function from N to set of
states", you again seem to refer to 'immaterial activity'. It seems
to me that what you are saying amounts to this:
If it is the case that, per comp, it is the 'immaterial' activity of
the running program, regardless of specific implementation, that
implements the function and hence the mind, then this is
indistinguishable by the machine from it simply *being* the function
and hence the mind. Standard comp is then seen to refute - or at
least make irrelevant - its own basis in materiality. Is this right?
>> And in any
>> case, in what way is step 8 intended to extend intuition beyond my own
>> argument, which - as I have tried to show - also elicits the insight
>> that the direct supervention of 'functional' relations on functions
>> themselves - not on their arbitrarily-defined physical tokens - is
>> central to the recovery of 'mind' from computation.
> See above.
Have I succeeded in answering my own question?
> The discovery of the universal machine is the creative bomb which
> makes comp possible and plausible. Universal machine, like computers
> and brains, are not trivial mathematical object at all. To study comp
> without computer science, is like doing cosmology without QM and GR.
> Of course we can have the deepest intuition right, by experience, but
> to make a sharble verifiable theory, I am afraid we cannot dismiss
> some math ...
Vous avez raison cher maitre, j'en suis sur.
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