Transcript The Knowledge Argument - Vienna University of Technology

The Knowledge Argument
A-Consciousness and
P-Consciousness (cont.)
Review
Access Consciousness: a state wherein
informational mental content is available to
reasoning and rational control of action
Phenomenal Consciousness: qualia, raw feels,
“what it is like”
Possible relationship between A- and P-Consciousness
1)
They are distinct in concept and separable in reality
There are actual cases of P- without A-Consciousness or Awithout P-Consciousness, e.g. blindsight, background noise
2)
They are conceptually distinct but empirically
inseparable
In humans, P and A consciousness always go together, but we
can imagine in other creatures they could come apart, e.g.
zombies (A without P) and floaters (P without A)
3)
They are not even conceptually distinct
P-consciousness is a necessary component of A-consciousness.
A-consciousness necessarily feels the way it does. Zombies are
inconceivable.
Other Characterizations of
Consciousness
1) Self-Consciousness
Sometimes consciousness is defined as self-consciousness.
In other words, it is claimed that consciousness is an
awareness of the world in relationship to one’s self, so
that a concept of self is necessary for consciousness.
“Perhaps consciousness arises when the brain’s simulation
of the world becomes so complete that it has to include
a model of itself” (Dawkins 1981)
Self-consciousness = a higher-order consciousness
Self-Concept:
self vs. environment
self vs. others
A kind of Access Consciousness
Can a creature have P-consciousness without
self-consciousness?
Block says, obviously yes.
Most people say yes. Some rare philosophers say no.
Mirror test for self-consciousness:
Meant to show if animal/person is self-conscious.
Spot put on forehead of dog/chimp/baby and dog/chimp/baby
put in front of mirror.
If they react to mirror appropriately, e.g. touch their own
forehead, they are said to be self-conscious.
Dogs, cats, birds fail.
Chimps, elephants, dolphins pass.
Babies pass after 1½ years old.
Are dogs nevertheless conscious?
2) Monitoring-Consciousness
Consciousness is internal monitoring (proposed by Lycan)
Consciousness consists of a scanning of internal
mechanisms that monitor perception, psychological
states, etc. and integrating the information received
What about laptop computer that contains internal
monitoring program?
Lycan: consciousness is a spectrum. Laptop computers are
a little bit conscious.
Block: This is only A-consciousness, not P-consciousness
Thought Experiments about
Color Consciousness
Philosophers of consciousness love to talk about color.
Experience of color perception is
a prime example of qualia.
The experience of color is
P-consciousness, but the ability
to discriminate color is a function
of A-consciousness
But, these thought experiments are really about consciousness
-- color is just an example.
These thought experiments could be reformulated to be about
tastes, smells, sensations or sounds.
1) The Inverted Spectrum
A precursor to the knowledge argument.
First proposed by John Locke in 17th century
Imagine that you see colors in exactly the
opposite way as I do.
Where I see green, you see red,
where I see yellow, you see blue, etc.
You and I still use color words in exactly the same way – we agree
that the sky is blue, even though we experience the color of the sky
differently.
Color discrimination functions the same in both of us.
Argument against functionalism:
Since color perception in both of us is functionally the same, but
our qualia is different, functionalism about qualia must be wrong.
Argument against physicalism:
If no physical investigation can show that our color experience is
different, physicalism must be wrong.
Objection to the inverted spectrum scenario:
Is it really possible for color experience to be inverted with
no behavioral (functional) differences?
Consider: The sky appears “orange” (as you see orange) to
me, but I say that the color of the sky is cool, soothing
and peaceful, and it reminds me of refreshing water,
bluebells and bluebirds.
Can I really see “orange” and have this response?
What is it like for me to see “orange” for blue? Is it like
seeing orange is for you, or is it like seeing blue is for
you?
Dennett: “qualia” is no more than the combination of
physiological responses, associations and reactive
dispositions caused by a stimulus.
2) The Knowledge Argument
Frank Jackson
“Epiphenomenal Qualia”
1982
“Qualia freak”
Argues that physicalism is false, and qualia is
epiphenomenal.
What “physicalism” means:
Everything is physical
All (correct) information is physical information.
All facts are physical facts.
Remember: supervenience
The mental supervenes on the physical.
Thoughts, feelings, ideas, qualia all supervene on the
physical.
What “physicalism is false” means:
There are non-physical facts.
OR
There are non-physical properties.
Jackson’s claim:
Qualia is non-physical.
Anything non-physical can have no effect on the physical
world (because of causal closure)
Hence, qualia is epiphenomenal
Fred
The knowledge argument has two parts:
1)
2)
Fred
Mary
Fred is the lesser known.
Fred can distinguish two completely distinct colors in objects
that we call “red”. He calls them red1 and red2.
For Fred, these colors are as distinct as blue and yellow are
for us.
He can use this ability to sort (e.g.) tomatoes reliably into two
categories. The categories look the same to us (i.e. red),
but he can always tell them apart.
We are colorblind with regard to red1 and red2.
We can never know (except by direct experience, i.e. a
partial brain transplant) what red1 and red2 are like.
Physical investigation cannot tell us what red1 and red2 are
like, so these concepts are non-physical.
Is this the same as we cannot tell what it is like to be a bat?
No. We share most types of subjective experience with
Fred, but we cannot know what this particular subjective
property is like to experience. We cannot even know
what it would be like for us to see red1 or red2.
Two possible class-level graphs for Fred’s red qualia
Color
Blue
Red
Yellow
Red1
John
distinguish
distinguish
Red2
Fred
Color
Blue
Yellow
Red1
Red2
Mary
Mary is the second and more famous part of the Knowledge
Argument.
Mary Imprisioned
Mary is imprisoned in a black-and-white room
with a black and white TV
Mary’s skin, blood, etc. dyed grey?
let’s just say Mary is colorblind
Mary is a brilliant scientist.
She learns all the physical facts
about colors and the neurophysiology
of vision (how we see color), including:
• which wavelength combinations from the sky stimulate
the retina (Jackson’s example)
• how the stimulation of our eyes causes the brain state
changes that result in the speech act “the sky is blue”
(Jackson’s example)
• what changes in brain states occur when we see or
imagine color and how these changes affect all other
brain states (Inglis’ elaboration)
Mary freed
When Mary comes out of the room (or has surgery
to give her color vision), she sees colors for the
first time.
Is she surprised?
“Oh, that’s what blue looks like!”
Does she learn something?
Jackson: Yes, obviously she learns something!
The Argument
P1 Mary knew all the physical facts about color vision
P2 Mary learned something new about color vision
Conclusion: What she learned was not a physical fact.
Hence: There are non-physical facts.
Facts about qualia are non-physical facts.
Modal-level graph for Mary’s new fact
all physical facts
subClassOf
know
not subClassOf
all physical facts about color vision
Mary
some fact about color vision
learn
Responses
1)
Mary doesn’t learn anything new
Jackson is begging the question.
Jackson says Mary knew all the physical facts, and yet
learned something new. Obviously, this presupposes
that all physical facts do not cover all possible facts.
You can object that P1 is impossible. It is impossible for us
to learn all the facts about human visual processing
Or, if you accept P1 and you don’t beg the question and
you assume that there are only physical facts, then
you conclude P2: Mary doesn’t learn anything new.
If Mary doesn’t learn anything new, why does it seem like she
would learn something new?
It is very hard to understand what it would be like to know all
the physical facts about the perception of color in human
beings.
Because we cannot imagine what it is like to know all the
physical facts, our intuition lets us down.
We cannot now imagine what complete physical knowledge of
visual processing will allow us to understand in the future.
Perhaps brain fMRI studies can detect differences between
colorblind people and people with normal color sight
(also see http://www.ugr.es/~setchift/docs/2006-phantom_colors_in_color_blind_synaesthete.pdf).
If there are significant differences, then once Mary sees
colors, her fMRI should change to the ‘normal’ category.
2) The ability response
Mary does learn something new, but what she learns is not
a fact.
Mary learns know-how.
Not all knowledge is factual knowledge. Some knowledge
is know-how, e.g. how to ride a bicycle.
Mary learns how to recognize colors, how to imagine and
remember them.
Perhaps this could again be detected by brain fMRI studies.
3) Mary doesn’t learn any new facts, but she learns old
facts under a new presentation.
Mary learns no new facts about color.
She learns to experience old facts in a new way.
Knowing from a subjective point-of-view and knowing from
an objective point-of-view are two different ways of
knowing, but can both be knowledge of the same facts.
Mary could objectively know how fMRIs look like for
people with normal color sight, yet not subjectively know
color qualia until after her surgery.
Related argument: subjective facts are also physical facts,
but can only be known subjectively. So, she does learn
new facts, but physicalism is not false.
Jackson’s change of heart
In 1982, Jackson thought that the knowledge argument
proved that qualia was non-physical and supported
epiphenomenalism.
Later, he changed his mind. He decided that physicalism is
most likely correct, and the knowledge argument is
misleading, but still interesting as a challenge to be
answered – how can it be wrong and yet seem so right?
In 2003 (http://consc.net/neh/papers/jackson.htm), he wrote:
“Most contemporary philosophers given a choice between
going with science and going with intuitions, go with science.
Although I once dissented from the majority, I have
capitulated and now see the interesting issue as being
where the arguments from the intuitions against
physicalism—the arguments that seem so compelling—go
wrong.”
Readings for next week
Focus:
Daniel Wegner (2003), “The mind's best trick: How we experience
conscious will”. http://web.gc.cuny.edu/cogsci/private/wegner-trick.pdf
Zelazo & Thompson, “Is Thought Unconscious?”, in The Cambridge
Handbook of Consciousness, pp. 357-359.
http://books.google.com/books?id=o9ZRc6FDg8C&printsec=frontcover&dq=The+Cambridge+Handbook+of+Cons
ciousness#PRA1-PA1,M1
Extra:
Levy, Neil, (2005), “Are Zombies Responsible? The Role of Consciousness
in Moral Responsibility”.
http://au.geocities.com/neil_levy/Documents/articles/consciousness_MR.pdf