2009/9/2 Flammarion <peterdjones.domain.name.hidden>:
>> and is thus not any particular physical
>> object. A specific physical implementation is a token of that
>> computational type, and is indeed a physical object, albeit one whose
>> physical details can be of any variety so long as they continue to
>> instantiate the relevant computational invariance. Hence it is hard
>> to see how a specific (invariant) example of an experiential state
>> could be justified as being token-identical with all the different
>> physical implementations of a computation.
>
> I was right.
>
> A mental type can be associated with a computational
> type.
>
> Any token of a mental type can be associated with a token
> of the corresponding computational type.
But what difference is that supposed to make? The type association is
implicit in what I was saying. All you've said above is that it makes
no difference whether one talks in terms of the mental type or the
associated computational type because their equivalence is a posit of
CTM. And whether it is plausible that the physical tokens so picked
out possess the causal efficacy presupposed by CTM is precisely what I
was questioning.
>> But even on this basis it still doesn't seem possible to establish any
>> consistent identity between the physical variety of the tokens thus
>> distinguished and a putatively unique experiential state.
>
> The variety of the physical implementations is reduced by grouping
> them
> as equivalent computational types. Computation is abstract.
> Abstraction is
> ignoring irrelevant details. Ignoring irrelevant details establishes a
> many-to-one relationship : many possible implementations of one mental
> state.
Again, that's not an argument - you're just reciting the *assumptions*
of CTM, not arguing for their plausibility. The justification of the
supposed irrelevance of particular physical details is that they are
required to be ignored for the supposed efficacy of the type-token
relation to be plausible. That doesn't make it so.
>> On the
>> contrary, any unbiased a priori prediction would be of experiential
>> variance on the basis of physical variance.
>
> Yes. The substance of the CTM claim is that physical
> differences do not make a mental difference unless they
> make a computational difference. That is to say, switching from
> one token of a type of computation to another cannot make
> a difference in mentation. That is not to be expected on an
> "unbiased" basis, just because it is a substantive claim.
Yes it's precisely the claim whose plausibility I've been questioning.
> The variety of the physical implementations is reduced by grouping
> them
> as equivalent computational types. Computation is abstract.
> Abstraction is
> ignoring irrelevant details. Ignoring irrelevant details establishes a
> many-to-one relationship : many possible implementations of one mental
> state.
Yes thanks, this is indeed the hypothesis. But simply recapitulating
the assumptions isn't exactly an uncommitted assessment of their
plausibility is it? That can only immunise it from criticism. There
is no whiff in CTM of why it should be considered plausible on
physical grounds alone. Hence counter arguments can legitimately
question the consistency of its claims as a physical theory in the
absence of its type-token presuppositions.
Look, let me turn this round. You've said before that you're not a
diehard partisan of CTM. What in your view would be persuasive
grounds for doubting it?
David
>
>
>
> On 2 Sep, 21:20, David Nyman <david.ny....domain.name.hidden> wrote:
>> 2009/9/2 Flammarion <peterdjo....domain.name.hidden>:
>>
>> > i suspect you are mixing types and tokens. But I await an answer to
>> > the question
>>
>> Well, a computation is a type,
>
> A type of computation is a type.
>
> A token of a type of computation is a token.
>
>> and is thus not any particular physical
>> object. A specific physical implementation is a token of that
>> computational type, and is indeed a physical object, albeit one whose
>> physical details can be of any variety so long as they continue to
>> instantiate the relevant computational invariance. Hence it is hard
>> to see how a specific (invariant) example of an experiential state
>> could be justified as being token-identical with all the different
>> physical implementations of a computation.
>
> I was right.
>
> A mental type can be associated with a computational
> type.
>
> Any token of a mental type can be associated with a token
> of the corresponding computational type.
>
> The difficulty comes from mixing types and tokens.
>
>> It might appear that a
>> defence against the foregoing is to say that only the appropriate
>> functionally-distinguished subsets of the entire implementing
>> substrate need be deemed tokens of the relevant computational type,
>> and that actual occasions of experience can be considered to be
>> token-identical with these subsets.
>
>> But even on this basis it still doesn't seem possible to establish any
>> consistent identity between the physical variety of the tokens thus
>> distinguished and a putatively unique experiential state.
>
> The variety of the physical implementations is reduced by grouping
> them
> as equivalent computational types. Computation is abstract.
> Abstraction is
> ignoring irrelevant details. Ignoring irrelevant details establishes a
> many-to-one relationship : many possible implementations of one mental
> state.
>
>> On the
>> contrary, any unbiased a priori prediction would be of experiential
>> variance on the basis of physical variance.
>
> Yes. The substance of the CTM claim is that physical
> differences do not make a mental difference unless they
> make a computational difference. That is to say, switching from
> one token of a type of computation to another cannot make
> a difference in mentation. That is not to be expected on an
> "unbiased" basis, just because it is a substantive claim.
>
>>Hence continuing to
>> insist on physically-based token-identity seems entirely ad hoc.
>
>
> Identity of what with what?
>
>> The unique challenge facing us, on the assumption of primitive
>> materiality, is the personally manifest existence of an experiential
>> state associated with a physical system. The first person gives us a
>> unique insight in this instance which is unavailable for other
>> type-token analyses. Ordinarily, picking out functional invariance in
>> physical systems is unproblematic, because the invariance is one of
>> type, not of token.
>
> Uhhh....exactly how does the first person insight
> break the invariance-of-type-with-variance-of-token thing?
>
>>The token may vary but the type-token association
>> is unharmed.
>
> So long as it is a token of the same type, yes.
>
>>But, uniquely, this doesn't hold for a theory of mind
>> based on primitive materiality, because now we have a unique
>> "token-identity" - mind-body - and thus it is inconsistent to expect
>> to substitute an entirely different type of body and expect no
>> substantive change on the other side of the identical doublet.
>
> Why? I see nothing there except blunt dogmatic insistence.
>
> In general, randomly selecting another body will lead to another mind.
> But
> that is not different from saying that randomly selecting differently
> configured hardware will lead to a different computation. The point of
> CTM is that making a non-random substitution -- that is, picking
> another
> token of the same type of computation -- will also automatically
> amount to picking another
> token of the same type of mentation. I have no idea why you think
> introducing
> a first person would make a difference.
>
>> The
>> resort of desperation is of course to disregard this unique
>> distinction, or worse to relegate experience to mere typehood; but in
>> that case we eliminate it from concrete existence.
>>
>> David
>>
>> >> No, I was querying whether Brent was implying this by his reference to
>> >> mental states realised in Platonia but nonetheless deemed to supervene
>> >> on physical process. But without such dual supervention, where does
>> >> that leave CTM+PM? Either we're appealing to
>> >> experience=computation=invariant, or we're appealing to
>> >> experience=physical process=variant.
>>
>> > Well, I've asked before, but what does (in) variant mean here?
>
> And i still haven't found out.
> >
>
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Received on Thu Sep 03 2009 - 01:26:01 PDT