[lit-ideas] Re: The Causal Theory of Perception
- From: Omar Kusturica <omarkusto@xxxxxxxxx>
- To: "lit-ideas@xxxxxxxxxxxxx" <lit-ideas@xxxxxxxxxxxxx>
- Date: Wed, 5 Feb 2014 15:07:12 -0800 (PST)
The term 'illusion' can use some illumination. 'Illusion' usually refers to
experiences in which we perceive an actual object but perceive it inaccurately;
for instance, we perceive a real ship on the horizon but it appears to us
smaller than it is, or more distant than it is, or perhaps we are incorrect
about its shape or color etc. 'Hallucination' refers to cases in which we
actually perceive objects that are not there, and here it is possible to have a
visual hallucination and still retain an awareness that the perceived 'object'
is not real, and it is possible to believe that the perceived 'object' is real.
(Both cases are known medically.) The latter stronger case might be
characterized as a delusion, at least as a temporary delusion. Austin in Sense
and Sensibilia makes the point about Ayer's loose usage of 'illusion' and
'delusion', frequently making it sound as if they were interchangeable.
Well, just saying, I am not making any metaphysical points here, just trying to
distinguish the terms.
O.K.
On Wednesday, February 5, 2014 7:46 PM, Donal McEvoy
<donalmcevoyuk@xxxxxxxxxxx> wrote:
There is much more in the last post by JLS than is addressed here: for example,
we could detour into examining the so-called 'Argument from Illusion'.
I have tried to indicate that there is much that commonsense gets generally
right in this area - for example, the commonsense view that there is an
'internal world' (of experience) and an 'external world' (which is independent
of experience and which has causal affects on the 'internal world'). No one
with commonsense thinks that when they shut their eyes the "objects" that
disappear from view in their 'internal world' of experience disappear from the
'external world' (nor is it a misuse to speak of "objects" in this way in order
to make this point: it does not follow of course that the "object" as
experienced in the 'internal world' is
the same thing, for all purposes, as the "object" in the external world). Nor
is it commonsense to think there is only my 'internal world' and nothing
'external' to which it pertains and which causally affects it. All of this
important stuff commonsense gets right and there is no valid philosophical
challenge to commonsense here.
What happens is that in developing our theory of knowledge in commonsense terms
we start to get into a mess: we might think all knowledge is derived from
experience in some way, but then reflect that we only therefore have knowledge
of what we experience - and therefore only knowledge of an 'internal world',
for experience belongs in our 'internal world' not in any 'external world'.
Soon our commonsense empiricism (our theory of knowledge) is rendering
problematic whether there is any 'external world' as per our commonsense
realism.
It is notable that the main arguments
against commonsense realism are not based on anything like a convincing
argument that there is no distinction between an 'internal' and 'external'
world, but on arguments derived from making a mess in our theory of knowledge.
Popper's view is that this apparent clash between commonsense realism and a
commonsense theory of knowledge is real and unresolvable: and the solution is
to reject one or the other. In Popper's view, we should reject the commonsense
theory of knowledge as mistaken while accepting commonsense realism as
(largely) true (as far as it goes). This point is one of the major underlying
themes of "The Self and Its Brain": and Popper wishes to show not only how the
mind looks in the light of his epistemology but indicate how this epistemology
dovetails with everything we know about the workings of the brain and other
sense organs.
In this model, what is important is not 'causal role'
per se - for the processes are elaborate and multi-causal: what really matters
is that the processes work in the way of 'trial-and-error'. We can have much
more insightful discussion based on examining the details of this kind of model
than speaking in terms of mere 'causal role'.
Of course, we do not experience the vast 'trial-and-error' processes that are
involved when we open our eyes and experience 'seeing an object': we neither
experience the vast evolutionary 'trial-and-error' history that underpins the
eye we inherit from our ancestors nor do we experience the complex, rapid
'trial-and-error' processes involved when that inherited eye (and its brain)
springs into action when we raise our eyelid. But our models, including
scientific models, can throw much surprising light on all these processes -
much more light than we get by thinking about what it feels like when we
experience 'seeing an object', as our experience is far from
'transparent' as to how it is formed.
Our 'experience is not transparent as to 'causal roles' either, as these must
be allocated in terms of detailed understanding of the relevant processes.
Dnl
Ldn
On Wednesday, 5 February 2014, 14:00, "Jlsperanza@xxxxxxx" <Jlsperanza@xxxxxxx>
wrote:
Wittgenstein showed the drawing to a student:
"What do you see?"
"A rabbit".
"Well, it's a duck, you know."
Strictly, what is seen is a _drawing_ of a duck (or rabbit), rather than a
duck (or rabbit) itself. This is expanded by
http://books.google.com/books?id=r5s27wymdh0C&printsec=frontcover&dq=Wittgen
stein+theory+of+perception&hl=it&sa=X&ei=WUHyUrnkM6HXygGjIQ&ved=0CC4Q6AEwAA#
v=onepage&q=Wittgenstein%20theory%20of%20perception&f=false
C. Good, "Wittgenstein and the theory of perception", where Good expands on
Grice's correct analysis of 'see':
"I saw Elvis on television".
This Good contrasts with:
"I imagined Elvis on television"
because a causal link can be postulated between Good's having seen Elvis
Presley on television and Elvis Presley. Similarly, an editor of the Longman
Dictionary, one argued against including as an entry for 'horse':
horse: 1. a mammal. 2. representation of a horse, as in
a painting.
Still, it is not unfair to regard the Causal Theory of Perception as a
version of Representationalism, but then, as Grice notes, 'represent' is a
trick of a word (his favoured uses of 'represent' are cases as when we say
that
a cricket team 'represents' England in an international match).
Good regrets that Grice does not spend enough time on sensory evidence and
behavioural output as it relates to verbs like 'see', but Grice does. True,
in 1961, these references are merely sketchy, but in "Method in
philosophical psychology" (1975) he has attained the status of a Functionalist
(alla
D. K. Lewis) and he's more than ready to reformulate perceptual beliefs (as
we may call them) in terms of both sensory input and behavioural output.
His dismissing such an account in the earlier 1961 "Causal Theory" may thus
be explained by his
resistance to allow the last word to be the proponent
of an 'ideal' or 'more scientific' language than the ordinary language that
he finds himself articulating.
The nuances he discovers and makes explicit go well beyond the rough
generalisations of the type he was familiar with (and which were especially
popular at Cambridge, where he is reading "Causal Theory") to the effect that
meaning is use, which (as we can argue) is not. He therefore spends quite
some time in proposing counterexamples to alleged ordinary-language specimens
that would seem to refute the Causal Theory of Perception as it relies on
more or less transparent (and 'immune' or 'incorrigible') sense-datum
reports.
McEvoy has been exploring Grice's (and others') references to 'material
object' (that Grice symbolises as "M") having property "Phi" (or P) or
'possessing
property P', as Grice prefers, and their references in causal
accounts of verbs of perceiving such as 'see' and actual accounts of the
phenomena
involved. McEvoy distinguishes, properly, between the 'internal world' (I
think his phrase is) of the perceiving subject and the alleged 'external
world' (where "M" belongs). He prefers to rectify the causal theory of
perception via an evolutionary account that rules out more fine-grained
accounts
of the causal process involved as redundant for survival (or not).
In "The Causal Theory of Perception", Grice keeps mentioning the Sceptic,
and it should be borne in mind that his account provides a reason for the
sceptic's doubt. I'm less sure other versions of the causal theory do.
Grice mentions in passing, too,
http://www.hist-analytic.com/GRICE.pdf
for which I provide further material in ps, the argument from illusion (i)
and Moore's proof of an external world (ii). He rather concentrates on
different types of implication that attach (or fail to attach) to sense-datum
reports like "It looks to me as if there is a red tomato in the basket".
Cheers,
Speranza
---
(i) The argument from illusion is an argument for the existence of
sense-data. It is posed as a criticism of direct realism. Naturally occurring
illusions best illustrate the argument's points, a notable example concerning a
stick: I have a stick, which appears to me to be straight, but when I hold
it underwater it seems to bend and distort. I know that the stick is
straight and that its apparent flexibility is a result of its being seen
through
the water,
yet I cannot change the mental image I have of the stick as
being bent. Since the stick is not in fact bent its appearance can be
described
as an illusion. Rather than directly perceiving the stick, which would
entail our seeing it as it truly is, we must instead perceive it indirectly,
by way of an image or "sense-datum". This mental representation does not
tell us anything about the stick's true properties, which remain inaccessible
to us. With this being the case, however, how can we be said to be certain
of the stick's initial straightness? If all we perceive is sense-data then
the stick's apparent initial straightness is just as likely to be false as
its half-submerged bent appearance. Therefore, the argument runs, we can
never gain any knowledge about the stick, as we only ever perceive a
sense-datum, and not the stick itself. This
argument was defended by A. J. Ayer. A
critical argument would be as follows: Because the stick provides a
contrasting surface in the surrounding water, the bent appearance of the stick
is
evidence of the previously unaccounted for physical properties of the
water. It would be a mistake to categorize an optical effect resulting from a
physical cause as sensory fallibility because it results from an increase in
information from another previously unaccounted for object or physical
property. Unless the water is not taken into consideration, the example in
fact
reinforces the reliability of our visual sense to gather information
accurately. This criticism, which was most strongly voiced by J.L. Austin, is
that perceptual variation which can be attributed to physical causes does not
entail a representational disconnect between sense and reference,
owing to
an unreasonable segregation of parts from the perceived object. Further
arguments are based on the extended mind theory, which appeals to external
sources of mental items. For example, the theory holds that perception is the
result of a complex interaction of mind, body and the environment. This
would rule out internal items such as sense data as referred to in the
statement of the argument.
(ii) Here is one hand is a philosophical argument created by George Edward
Moore against philosophical skepticism and in support of common sense. The
argument takes the form: Here is one hand, And here is another. There are
at least two external objects in the world. Therefore an external world
exists. G. E. Moore (1873—1958) wrote A Defence of Common Sense and Proof of
an
External World. He posed skeptical hypotheses, such as "you may be
dreaming" or "the world is 5 minutes old", creating a situation where it is
not
possible to know that anything in the world exists. These hypotheses take the
following form:
The skeptical argument: Where S is a subject, sp is a skeptical
possibility, such as the brain in a vat hypothesis, and q is a knowledge claim
about
the world: If S doesn't know that not-sp, then S doesn't know that q; S
doesn't know that not-sp; Therefore, S doesn't know that q. Moore's response:
If S doesn't know that not-sp, then S doesn't know that q; S knows that q;
Therefore, S knows that not-sp. Moore does not attack the skeptical premise;
instead, he reverses the argument from being in the form of modus ponens
to modus tollens. This logical maneuver is often called a G. E. Moore shift
or a Moorean shift. Moore famously put the point into dramatic relief with
his
1939 essay Proof of an External World, in which he gave a common sense
argument against skepticism by raising his right hand and saying "here is
one hand," and then raising his left and saying "and here is another". Here,
Moore is taking his knowledge claim (q) to be that he has two hands, and
without rejecting the skeptic's premise, proves that we can know the
skeptical possibility (sp) to be not true. Moore's argument is not simply a
flippant response to the skeptic. Moore gives in Proof of an External World,
three requirements for a good proof. (1) the premises must be different from
the conclusion, (2) the premises must be demonstrated, and (3) the conclusion
must follow from the premises. He claims that his proof of an external
world meets those three criteria. In his 1925 essay A Defence of Common Sense
he argued against idealism and
skepticism toward the external world on the
grounds that they could not give reasons to accept their metaphysical
premises that were more plausible than the reasons we have to accept the
common
sense claims about our knowledge of the world that skeptics and idealists
must deny. In other words, he is more willing to believe that he has a hand
than believe the premises of a strange argument in a university classroom.
"I do not think it is rational to be as certain of any one of these ...
propositions". Not surprisingly, those inclined to skeptical doubts often
found Moore's method of argument not entirely convincing. Moore, however,
defends his argument on the surprisingly simple grounds that skeptical
arguments
seem invariably to require an appeal to "philosophical intuitions" that we
have considerably less reason to accept than we have for the
common sense
claims that they supposedly refute. The skeptical argument takes the form of
modus ponens: If A then B; A; Therefore B. Moore's argument flips the
modus ponens structure into a modus tollens: If A then B; Not B; Therefore not
A. This illustrates Fred Dretske's aphorism that "[o]ne man's modus ponens
is another man's modus tollens". Appeals of this type are subsequently
often called "Moorean facts". "A Moorean fact [is] one of those things that we
know better than we know the premises of any philosophical argument to the
contrary" The "here is one hand" idea, in addition to fueling Moore's own
work, deeply influenced Ludwig Wittgenstein, whose last writings were
devoted to a new approach to Moore's argument. These remarks were published
posthumously as On Certainty. See also: Samuel Johnson, to whom is attributed
the act of
hitting a rock with his foot as a "refutation" of immaterialism.
References: G. E. Moore," Internet Encyclopedia of Philosophy; Keith DeRose,
Responding to Skepticism; Dretske, F. (1995), Naturalizing the Mind,
Cambridge, Mass.: The MIT Press. Kelly, Thomas. "Moorean Facts and Belief
Revision, or Can the Skeptic Win?". Princeton University. Forthcoming in John
Hawthorne (ed.), Philosophical Perspectives, vol.19: Epistemology.
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