Lecture 20 Theories of Consciousness, Consciousness and the
Mind-Body Problem Slide 2 THEORIES OF CONSCIOUSNESS Slide 3
Dennetts Multiple Drafts Model Dennetts Multiple Drafts Model is
the conjunction of several theses. The Parallel Processing Thesis:
All mental states result from parallel processing, i.e., from many
simultaneous, interacting sub-processes. Example: you see red,
black and silver, as well as rectangular and circular shapes. Your
mind processes all these elements simultaneously, producing a
perception of a car. Slide 4 Dennetts Multiple Drafts Model, cont.
The Multiple Drafts Thesis: At any given time, ones parallel
processing system produces a variety of drafts, i.e., of sequences
of events that one could become conscious of. Example: You have a
conversation while driving. Your parallel processing system
produces two drafts: one consisting of the conversation and the
other consisting of the passing scenery. Slide 5 Dennetts Multiple
Drafts Model, cont. The No Editor-in-Chief-Thesis: There is no
mental faculty (editor-in-chief) that selects some drafts for
consciousness (publication) while rejecting others. The drafts that
we seem to be conscious of are typically those that have been
probed. Example: You have no memory of the passing scenery, but
only of the conversation. This might suggest that the conversation
draft was selected for publication and the scenery draft was not.
However, if someone were to probe your memory, you would remember
bits of the scenery. Slide 6 Dennetts Multiple Drafts Theory and
the Phi Effect (To view the experiment, go into Slide Show mode.)
The Phi Phenomenon is when a succession of still images produces a
perception of motion. At certain combinations of spacing and timing
of the two images, the perceiver will report that a dot moves from
left to right and that, half way through its motion, changes color.
(In this case, from green to red.) Slide 7 Dennetts Multiple Drafts
Theory and the Phi Effect, cont. Clearly, the brain uses the
information about the green and red dots and mistakenly infers that
the red light moved and changed color. Problem: If the brain uses
the information in this way, why do we not see the green light,
then the red light, and then the motion and color change? Slide 8
Dennetts Multiple Drafts Theory and the Phi Effect, cont. Two
Theories of the Phi Effect: The Stalinesque Theory: The perceptual
input is revised and the memory held fixed. We become conscious
only after the perceptual input has been revised. The Orwellian
Theory: We initially have conscious experiences of stationary dots.
However, our memory of our conscious experiences gets revised so
that we only have conscious experience of a moving dot. The two
theories differ over whether consciousness enters the scene before
or after the revisions. According to Dennett, there is no fact of
the matter as to which theory is correct; there are no fixed facts
of consciousness apart from probing, and no probing could favor one
of these theories over the other. Slide 9 CONSCIOUSNESS AND THE
MIND- BODY PROBLEM Slide 10 Nagel on Physicalism and Objectivity
Remember: physicalism is the thesis that only the entities studied
by the physical sciences, or entities composed of such entities,
exist. The physical sciences are objective in that they abstract
away from particularities. Example: F=ma abstracts away from the
color, etc., of the objects it describes. Nagels Contention: We
cannot reconcile the paricular, subjective features of experience
with physicalism. Slide 11 What Its Like to Be a Bat According to
Nagel, there is something that it is like to be a particular
conscious being. Example: There is something that its like to be a
bat. This what its like cannot be captured by objective physical
laws. Example: Full understanding of bat physiology will not give
us full knowledge of what its like to be a bat. Slide 12 Responses
to Nagel Does Nagel just mean that one conscious being cannot have
anothers experiences? If so, then his claim is trivially true, and
physicalism can explain its truth. Slide 13 Jacksons Knowledge
Argument Imagine Mary, who has been raised by perverse scientists
in a black and white room and who knows everything about the
neurophysiology of perception. Eventually she leaves the black and
white room and sees a bright red sunset. Jackson argues as follows:
1.When Mary sees the sunset, she comes to know that its like this
(pointing at a red object) to see redness. (Premise) 2.Mary
previously did not know that its like this to see redness.
(Premise) 3.Mary previously knew all the physical facts about
perception. (Premise) 4.That its like this to see redness is a
non-physical fact about perception. (From 1- 3) 5.There are
non-physical facts, and physicalism is false. (From 4, definition
of physicalism)
