[lit-ideas] Re: The Causal Theory of Perception
- From: Jlsperanza@xxxxxxx
- To: lit-ideas@xxxxxxxxxxxxx
- Date: Wed, 5 Feb 2014 09:00:17 -0500 (EST)
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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