Transcript Lecture 9: Consciousness

The Mind-Body Problem
&
What it is like to be a bat
Minds and Bodies
What is the connection between minds and bodies?
Are they made of the same stuff?
Three possibilities:
1) Physicalism: everything is physical
2) Dualism: there are two kinds of stuff, physical
and mental; or there are two properties of stuff,
physical properties and mental properties
3) Idealism: everything is mental
Dualism
Motivation for dualism: the inexplicability of the
mental arising from the physical
How can purely physical stuff possibly give rise to
our mental life: to consciousness, emotions and
intelligence?
Doesn’t it seem obvious that our minds are more
than our brains? Don’t we have souls? Aren’t we
“ghosts in the machine”?
Dualism in the west is primarily descended from the
Judeo-Christian tradition.
Types of dualism
1) Substance dualism
There are two types of stuff: mental stuff and physical
stuff. Our minds are composed of mental stuff. Everything
else in the universe is composed of physical stuff.
2) Property dualism
There is only one type of substance, but stuff has two
types of properties: mental properties and physical
properties.
Substance Dualism
Rene Descartes (1596-1650 )
The universe contains two types of substance, matter
(physical substance) and mind (mental substance).
Matter
Mind
Spatially extended
Divisible
Mechanistic
Does not think
Dubitable
not spatially extended
indivisible
indeterministic
thinks
indubitable
Descartes
“I am a thinking thing”
A version of Descartes’s argument:
P1 I know I am a thinking thing (a mind)
P2 I do not know that I am a body
C Therefore, mind and body are different things.
But compare:
P1 I know Clark Kent is my friend
P2 I do not know Superman is my friend
C Therefore, Clark Kent and Superman are different things
A modern argument for dualism
David Chalmers
Contemporary Australian philosopher
b. 1966
The conceivability of zombies
– David Chalmers (1996), The Conscious Mind: In Search of a
Fundamental Theory
A zombie is an imaginary creature
that is physically identical to us but
which has no conscious mind. It
behaves exactly like we do, but has
no feelings, no inner life.
The claim is that if zombies are
conceivable then the physical is
distinct from the mental, i.e.
dualism is true.
Problems: is conceivability enough
to prove possibility?
Are zombies really conceivable?
The interaction problem of dualism
If mind and matter are two completely different
substances (or properties), how can they
interact? To affect matter, it would seem that
mind must have some physical properties, and
vice versa.
Objections to dualism
1) Intuitive appeal to consistency: why should the
world inside our heads be different from everything
outside our heads?
2) Interaction problem
3) No evidence
4) Ockham’s razor
–
–
In explanations, entities should not be multiplied
unnecessarily
i.e. the simplest explanation is generally to be preferred.
5) Lack of explanatory power
Physicalism
Definitions of physicalism
Physicalism: the belief that the only kinds of things are
physical things and the only kinds of properties are
physical properties
Physicalism is the belief that everything in the universe can
be explained in terms of physics (thus, there is no
mysterious non-physical stuff that does not follow
physical laws)
All mental phenomena can be explained in terms of nonmental phenomena
Physicalism with regard to the mind
The mind is a biological machine (maybe like a
computer).
If we understand how the mind works physically, we
can understand thoughts, feelings, consciousness
A computer or robot could theoretically
have a mental life (i.e. consciousness)
The Hard Problem
of Consciousness
Easy and hard problems of consciousness
Distinction proposed by David Chalmers
The easy problems:
• finding the neural correlate of consciousness
• explaining the ability to apply information to thinking and
behavior
• explaining the ability to focus attention, recall items from
memory, integrate perceptions, etc.
The hard problem:
Why does consciousness feel the way it does? Why does it feel
like anything?
Why the problem is hard
“You can look into your mind until you
burst, and you will not discover neurons
and synapses and all the rest; and you
can stare at someone’s brain from dawn
till dusk and you will not perceive the
consciousness that is so apparent to the
person whose brain you are so rudely
eye-balling.“ (McGinn 1999)
“The problem of consciousness, simply put, is that we cannot understand
how a brain, qua gray, granular lump of biological matter, could be the
seat of human consciousness, the source or ground of our rich and varied
phenomenological lives. How could that ‘lump’ be conscious – or,
conversely, how could I, as conscious being, be that lump?” (Akins 1993
What is it like to be a bat?
Thomas Nagel
One of the most famous
papers in all of philosophy!
(1974)
We can never know what it feels like to be a bat.
Why a bat?
There is something
it is like to be a bat.
Compare:
Cloud, rock, tree – nothing it is to be like
Mosquito, frog, computer – who knows? People have
different intuitions.
Bats are mammals. Most people agree they have experiences –
they are conscious.
But, their consciousness is alien to us:
They “see” by sonar.
They fly and hang upside-down.
They lust for other bats.
We might be able to imagine what it would be like for us to live
and behave like a bat.
But we can’t imagine what it is like for a bat to be a bat.
Problem of subjectivity?
Nagel: not a problem of subjectivity
e.g. “no one can catch my catches”
It’s not that we cannot experience bat token
experiences, e.g. Billy the bat’s sonar qualia.
Bat qualia are mental types that other subjects could
also experience. But we cannot learn what these
types are like objectively.
Bat’s experience is subjective.
Consciousness = having a point of view
Scientific knowledge is objective.
“The view from nowhere.”
Example: lightning
– subjective: looks like a flash of light
– objective: electrical discharge
Study of objective science can never reveal the
character of subjective experience.
Is this the same as the problem of other minds?
Not quite.
What is it like to be an eskimo?
What is it like to be Tom Cruise?
Nagel: we can answer these questions fairly well by using our
imagination. But, the answer is accessible to us only because we
base our imagination on our own experiences. We need the
subjective experience of being human to imagine the experience of
others.
Objective science alone could not give us these answers.
A Martian could not learn from objective facts what it is like to be
human.
Science cannot explain consciousness in physical terms.
“I have not defined the term 'physical'. Obviously it does not apply
just to what can be described by the concepts of contemporary
physics, since we expect further developments. Some may think
there is nothing to prevent mental phenomena from eventually
being recognized as physical in their own right. But whatever else
may be said of the physical, it has to be objective.” (Nagel 1974)
Physical facts are objective.
Consciousness is subjective.
So consciousness can never be explained by physical facts.
Question: Is this right? Are only objective facts physical? Are the
objective and the subjective irreconcilable?
Is physicalism about mental states wrong?
Nagel: not necessarily
“It would be a mistake to conclude that physicalism must be false…. It
would be truer to say that physicalism is a position we cannot understand
because we do not at present have any conception of how it might be
true.” (Nagel 1974)
Example: we saying “mind is brain” is like pre-Socratic philosopher saying:
“matter is energy”
“Strangely enough, we may have evidence for the truth of something we
cannot really understand.” (Nagel 1974)
Example: caterpillar  butterfly
Readings
Read at least one of the following:
Andrew Morton, “Free Will” in Philosophy in Practice, Ch. 14.4-14.5, on
UMMoodle
Thomas Nagel, “Free Will” in What Does It All Mean?, Chapter 6, on
UMMoodle
Stephen Law, “Do We Ever Deserve to Be Punished” in The Philosophy Gym,
Chapter15, on UMMoodle