Newsgroups: comp.ai.philosophy
Path: cantaloupe.srv.cs.cmu.edu!das-news2.harvard.edu!news2.near.net!news.mathworks.com!udel!gatech!swrinde!pipex!uknet!festival!edcogsci!jeff
From: jeff@aiai.ed.ac.uk (Jeff Dalton)
Subject: Re: Dennett vs filling in (was Re: When is a simulation of a Y a Y? (Was Bag the Turing
Message-ID: <D3p451.H60@cogsci.ed.ac.uk>
Sender: usenet@cogsci.ed.ac.uk (C News Software)
Nntp-Posting-Host: bute-alter.aiai.ed.ac.uk
Organization: AIAI, University of Edinburgh, Scotland
References: <D3AB9n.Bs3@spss.com> <D3Fxt2.L2L@cogsci.ed.ac.uk> <D3LsBB.2v0@spss.com>
Date: Wed, 8 Feb 1995 19:15:00 GMT
Lines: 282

In article <D3LsBB.2v0@spss.com> markrose@spss.com (Mark Rosenfelder) writes:
>In article <D3Fxt2.L2L@cogsci.ed.ac.uk>,
>Jeff Dalton <jeff@aiai.ed.ac.uk> wrote:
>>markrose@spss.com (Mark Rosenfelder) writes:
>>>Here and in other parts of this section (e.g. the only other section that
>>>mentions blind spots, p. 8), Hardin uses entirely unobjectionable, neutral
>>>language, saying only that we are not aware of the blind spot (or of our
>>>own saccades, or of the shadows of retinal blood vessels, etc.).  
>>>
>>>However, this passage seems to me to go much further than merely "saying
>>>...that we don't notice the blind spots", as you claim; it actually declares 
>>>that the blind spot is filled in "from adjoining retinal regions", and even
>>>comments on how remarkable this process is.  Hardin does not say where
>>>this notion comes from; one would have to examine his own sources to find
>>>out.  I don't think that Dennett is misinterpreting anything Hardin
>>>says about "filling in".  
>>
>>The part about "from adjoining retinal regions" seems to me the most
>>telling.  Thanks for pointing it out.  But Dennett omits it, so presumably
>>he thinks it isn't needed as supporting evidence.
>
>You know exactly what Dennett is thinking, based on what he doesn't say?

I didn't say I knew exactly what he was thinking.  I said presumably
he thinks it isn't needed.  I'm assuming that if Dennett thought it
was *needed* he'd have included it, which seems like a reasonable
assumption to me.

>Isn't this just what you objected to in his discussion of Hardin?

No.  Dennett's interpretations get much further away from what Hardin
actually says.  Moreover, this is a minor point.  I'm not concluding
all that much from this one little bit of Dennett.

>>I would still say that what this "filling in" is more a place-holder
>>than a theory about what's actually going on, and that includes
>>filling in "from immediately adjoining retinal regions".  Hardin
>>doesn't say enough in the paragraph above for us to tell what his
>>views are in any detail.
>
>If you mean that Hardin doesn't explain his views in detail, I agree;
>but I don't agree that the ideas from the passage I quoted are a "place-
>holder".

I said it's more a place-holder than a theory.  The more important
side of this is that it's not a theory, or at least not one that's
at all detailed.  I assume that Hardin could say more if asked.

>I don't think you're doing Hardin any favors here; what exactly do 
>you think Hardin is calling "remarkable", if it's not a process of filling in 
>in the brain?  

A number of different things might be going on in the brain, and a
number of them might reasonably be called "filling in".  Indeed, most,
if not all, of Dennet's suggestions about what's goes on could
reasonably be called "filling in" (though not, of course, if you
insist on Dennett's interpretation of filling in -- see my previous
article).

I find the experiential aspects (e.g. that we don't notice a gap
or distortion as a result of the blind spot) pretty remarkable in
themselves.  It even may be that Hardin expected that some of his
readers wouldn't even know there was a blind spot.

> Perhaps Dennett is wrong; another
>post suggested that he might in fact be wrong about whether any "epistemic
>agents" in the brain care about the blind spot's contents.  But once he's
>given an alternative to "filling in", arguments for "filling in" need
>to be *justified*, not *assumed*.  And whatever exactly Hardin was saying
>about filling in (we may differ on how far he was committing himself), he 
>certainly offered no support for it.

I don't know whether Hardin offered support for it or not, and Dennett
doesn't tell me.  Moreover, Dennett doesn't give a clear explanation of
just what view he thinks Hardin holds.  (Is Hardin thinking of what
Dennett calls "bit-maps" or is he thinking of "figment" or is he just
confused or is the influence of the Cartesian Theater only that Hardin
uses the phrases such as "fill in" or ... ?)

Now, surely whatever Hardin thinks is going on in the brain he
shouldn't just assume it.  An alternative from Dennett is not
needed before that's the case.  In any case, Hardin's book came
before Dennett's, so Dennett's alternative was not available
(at least not from _Consciousness Explained_).

>>Of course, there *is* now, post
>>_Consciousness Explained_, a reason to avoid talk of filling-in,
>>namely that Dennett, and people convinced by Dennett, will apply
>>a distorting interpretation to what you say.
>
>You haven't shown that Dennett is distorting anyone.

Maybe not.  But then you haven't shown he isn't.

BTW, I've already said, a couple of times now, that Dennett may be
right about Hardin.  Ok, so far as I can tell he's not right about
phrases such as "filling in": they don't have to mean what Dennett
has them meaning, and you could produce alternatives yourself if you
wanted to.  However the what I'm still primarily addressing is whether
Dennett has shown various things, not whether he's right.

>>>As for whether this idea is a relic of the Cartesian Theater-- what
>>>would it take for you to accept that Dennett has "shown" this?  Citations
>>>of Descartes, and discussions of the pineal gland?  All Dennett has to
>>>show, IMHO, is that the authors he is discussing are assuming that the
>>>brain has to construct a *visual image* out of what the eyes see, for
>>>some part of the brain to look at.  Hardin's talk of filling in the blind
>>>spot certainly sounds like such an assumption is at work, perhaps
>>>unconsciously.
>>
>>Ah, unconsciously.  So no matter what even Hardin *says* in an attempt
>>to clear his name, we might *know better*.  "Cartesian materialism,
>>the view that nobody espouses but almost everybody tends to think
>>in terms of" [Dennett] strikes again.
>
>Talk about distortions.  What has Hardin said to "clear his name", and
>where does Dennett reject those statements?

I didn't say that Hardin *had* said anything to clear his name.

>Whatever Dennett has done to
>annoy you, is it really necessary to invent charges from thin air 
>against him?

Look, *you* said "perhaps unconsciously".  That's what I was
responding to.  I don't know how Dennett accounts for it.
(I hope we're not going to launch into a metadiscussion here.)

>Pointing out an assumption that hasn't been explicitly stated or justified
>is not an evil thing-- it's a service, a step forward.  It means that the
>assumption can be critically examined, and either supported or rejected.

That may be part of what Dennett does.  But even if we confine
ourself to that, what assumption, exactly?  And does Dennett
show that anyone is making *that* assumption?

>Perhaps you think that people are always very clear on what they are or
>are not assuming about the world. 

No, I think nothing of the sort.

>>I think it's fairly clear what Dennett means by the Cartesian Theater,
>>and the pineal gland needn't be involved.  But he seems to take it for
>>granted that there's a Cartesian influence and doesn't spend much
>>(if any) time arguing that there is or explaining how it works.
>>(Does he ever say it's a meme?)  He sometimes refers to the Cartesian
>>Theater as the "traditional view".  That, plus talk of vestiges or
>>(from your earlier article) relics, tends to suggest that it's
>>something we've picked up (in attenuated form) from the past.  
>
>Again, you haven't said what it would take to "show" you that these views
>are relics of the Cartesian Theater.  So far as I can see, whatever I or
>Dennett say, you can respond "But that didn't convince me."  

Sure, I *could* respond that way.  I could also respond by saying
that blue cows can't cut green cheese.  Look, it's not a question
even of convincing me.  I might feel I had reasons for being skeptical
even if Dennet spent hundreds of pages on the development and
propagation of the "traditional view" he calls the Cartesian
Theater, on the history of terms such as "mind" and "consciousness",
and on explaining how someone can think in terms of a view they
would reject if it were stated to them.  And I might resist even
if Dennett discussed how members of other cultures (with different
traditional views) account for perception and experience (if they
even see things in such terms) and showed that their thinking
did not show any affinities with Descartes's.

If Dennett did things of that sort, then it would at least be
clear that he'd made a substantial effort.  But Dennett doesn't.
Instead, he seems to take it for granted that there's a Cartesian
influence.

Now, I take it that you see this differently.  But if you do think
Dennett has shown there's a Cartesian influence, where does he show
it and how?

>I think you're taking Dennett's rhetoric much too literally.  "The Cartesian 
>Theater" is just a convenient label; he refers to Descartes at all simply as 
>a rigorous and influential expositor of rational dualism; he doesn't claim 
>that the assumptions he is criticizing actually derive directly from
>Descartes.

Right.  He claims they're "vestiges" of the Cartesian Theater, which
he says is the traditional view.  And that's what I'm looking for him
to show, or at least make significant efforts to show.

Of course, he does spend some time on Descartes.  I'll have to
look at that section again.

>My reading of what he's doing is to point out assumptions that all of us,
>including himself, started out with, and to subject them to critical
>examination. 

Why do you say "all of us"?  Sure, Dennett seems to think so (e.g.
"Cartesian materialism, the view that nobody espouses but almost
everybody tends to think in terms of" -- and (re "almost everybody"
vs "all of us") I'm not insisting on there being no exceptions).  
But you seem to agree.  Why is that?  Did you already think something
along those lines was the case, or did Dennett convince you?  If the
latter, perhaps you can tell me what it is you found convincing.

>He of course ends up rejecting them.  After reading him,
>you may or may not agree; but if you don't agree you will have to come up
>with reasons for what may have previously been unexamined presuppositions.

Sure, if I *had* such presuppositions and still wanted to defend
them.

>His claim is not at all that Hardin et al. are dualists, or believe in
>figment, but that they've said things that seem to assume, without 
>justification, that the brain constructs a visual image out of what the eyes 
>see, for some other part of the brain to look at. 

Unless "look at" is taken metaphorically, like when a procedure
is said to "look at" a data structure, I'd be surprised if Hardin
and the others Dennett mentions hold any such view.

I agree that Dennett is not saying they're dualists.  He's saying
their thinking is influenced by what Dennett calls "Cartesian
materialism".

I'm not sure exactly what Dennett is saying about Hardin at al and
"figment".  Dennett does say things like this:

  So much for figment!  But then, what does "filling in" mean,
  what _could_ it mean, if it doesn't mean filling in with figment?

and this:

  So much for pigment.  But still, we may be inclined to think
  that there is something that happens in the brain that is in
  _some_ important way analogous to covering an area with
  pigment -- otherwise we wouldn't want to talk of "filling
  in" at all.

But, as I remarked before, Dennett doesn't actually say Hardin
believes in figment.  When he introduces figment (2nd quote above),
he resorts to "we".

> In the case of Hardin,
>as I've said, the case seems to be justified: Hardin's statements about
>filling in from adjoining retinal areas are not explicitly supported.

Here you are again arguing that Dennett is right about Hardin.
But I can't tell from _Consciousness Explained_ that he's right.
Perhaps Hardin does give explicit support.

In any case, it's not clear what Hardin has in mind when saying
that there's filling in from adjoining retinal areas.  But one
thing he might have in mind is filling in entries in what Dennett
calls a "bit-map".  That's something Dennett thinks is an empirical
possibility, and Dennett doesn't seem to think "fill in" can be about
something like that (see above).

>You seem to be worried that Hardin, if he read these passages in Dennett,
>would cry out, "I've been misinterpreted!"  That's possible; but he might
>equally decide to supply more backing for his statement, or modify his
>statements to make no theoretical presuppositions.   Frankly I find these
>possibilities more complimentary to Hardin.

No, that's not my worry at all.  My worry (if you want to call it
that) is that people may suppose that Dennett has shown various
things that he hasn't.  I'm "worried" that people will say things
like this:

  Dennett shows (in _Consciousness Explained_) that the notion that
  the brain fills in some detailed picture of what the eyes see, even
  neatly airbrushing over the blind spot, is a fantasy, a relic of the
  Cartesian Theater.

and that other people will suppose that this is an established
fact, established by Dennett.

Now, if Hardin was misinterpreted, he might well point this out *and*
"supply more backing for his statement, or modify his statements".
They're not exclusive.  However, he might find it difficult to
remove *all* theoretical presuppositions.  ^_^

-- jd



