Physicalism
FROM LAST TIME: ABDUCTIVE
ARGUMENT FOR MATERIALISM
The Abductive Argument
Here’s an argument against Berkeley:
“Look, the existence of a mind-independent
reality is the best explanation for our
experiences. If tables and chairs etc. were ‘just
ideas’ that wouldn’t explain why everyone
looking in the same place sees the same thing.”
Reply: This requires that
the physical objects cause
our ideas. But no-one has
any clue how physical-tomental causation is
supposed to work. So this
can’t be the best
explanation.
Furthermore, according to corpuscularianism,
our ideas are caused (mysteriously) by the shape
size and motion of the corpuscles acting on our
sensory organs. But:
(a) Shape, size, and motion are ideas
(b) Ideas are passive: they cannot cause a
change in other ideas.__________________
(c) Therefore, shape, size, and motion can’t
cause a change in our ideas.
Outstanding Issues
OK, but how can Berkeley explain:
• The fact that our experiences are regular and
lawful.
• The fact that our experiences are intersubjectively verified.
• The fact that there’s a difference between
hallucination, imagination, and sensing.
• The fact that tables and chairs exist even
when no one is perceiving them.
Berkeley’s Metaphysics
Regularity
Inter-Subjectivity
Hallucination
Persistence
Why Believe It?
(a) Ideas can’t cause ideas; they are passive
(b) Physical substances can’t either; they don’t
exist_________________________________
(c) Presumably, then, a mental substance must
be the cause.
The Mind is Not Me
It is clear that I produce some of my ideas, as in
imagination.
But most of my ideas are not produced by my
own will; so they must be produced by the will
of another.
The Mind is Wise and Benevolent
Sense ideas (a) are more strong, lively, and
distinct than the ideas of imagination and (b)
have a steadiness, order, and coherence lacking
in the latter.
Berkeley says these facts testify to the “wisdom
and benevolence of [their] author”
RECEPTION
Samuel Johnson (1709-1784)
Samuel Johnson was a poet and essayist in
Britain, one of the most important British
literary figures, and a contemporary of Berkeley.
James Boswell, his biographer, conveys the
following story in Life of Samuel Johnson.
Samuel Johnson vs. Berkeley
“After we came out of the church, we stood talking
for some time together of Bishop Berkeley's
ingenious sophistry to prove the nonexistence of
matter, and that every thing in the universe is
merely ideal. I observed, that though we are
satisfied his doctrine is not true, it is impossible to
refute it. I never shall forget the alacrity with which
Johnson answered, striking his foot with mighty
force against a large stone, till he rebounded from it
– “I refute it thus.””
REDUCTIONISM
Life Force
Most cultures throughout
history have believed in
some sort of “life force.”
Qi in China, prana in India,
or élan vital in the West.
Vitalism
“Vitalists hold that living organisms are
fundamentally different from non-living entities
because they contain some non-physical
element or are governed by different principles
than are inanimate things.”
--“Vitalism,” Routeledge Encylopedia of
Philosophy
Vitalism
After the advent of chemistry in the West,
“vitalism” was associated with testable scientific
claims. For example:
• No organic material can be made from only
inorganic components.
• Certain processes (e.g. respiration,
fermentation) require living organisms to take
place.
Molière’s The Imaginary Invalid
1st DOCTOR:
Most learned bachelor
Whom I esteem and honor,
I would like to ask you the cause and reason why
Opium makes one sleep.
ARGAN:
...The reason is that in opium resides
A dormitive virtue,
Of which it is the nature
To stupefy the senses.
The Wöhler Synthesis
In 1828, German chemist
Friedrich Wöhler
synthesized the organic
chemical urea from
inorganic materials.
(Now we know how to
synthesize them all.)
The Periodic Table
41 years later, Dmitri
Mendeleev published a
periodic table of the
elements. It wasn’t the
first such table, but it was
the first to rearrange
elements out of strict
atomic-weight order and
to leave gaps where the
known elements didn’t fit.
Quantum Mechanics
Subsequently, the development of quantum
mechanics in physics allowed us to explain the
periodic chemical features that appear in the
table in terms of the physical properties of each
element.
Reductions
Biological
↓
Chemical
↓
Physical
Reductions
Mental? Moral? Modal?
↓?
Biological
↓
Chemical
↓
Physical
DEPENDENCE
Physicalism
Physicalism says that only physical objects and
only physical properties exist.
Does that mean that the three spooky M’s don’t
exist? What is it for everything to be physical?
Modality
There are ways that the world is. For example,
donkeys are not, in fact, capable of speech.
But there are also ways that the world could
have been. Donkeys could have been able to
talk, even though in fact they can’t.
Could Have Existed
Possible Worlds
Philosophers like to talk about “possible worlds.”
In this way of talking, every way that our world
could have been is a way that some world is.
So, for example, there’s a possible world where
donkeys talk
It could have been true that P
=
In some world it is true that P
Seurat, La Seine á La Grande-Jatte
Seurat, La Seine á La Grande-Jatte
Supervenience
The A-properties supervene on the B-properties
=def any two possible worlds with the same Bproperties have the same A-properties.
Problem
Ectoplasmic goo
Physicalism
So we might say that physicalism is the following
claim:
All properties supervene on physical properties.
Any two worlds with all the same physical
properties have all the same properties.
WHAT IS “PHYSICAL”?
Physicalism says that only physical objects and
only physical properties exist.
But what does it mean for something to be
physical?
First Pass
A property or object is physical =def that
property or object appears in the laws of physics
(as they now stand).
The Standard Model
Things That Might Be Missing
• A theory of gravity. Some physicists believe
there are particles called gravitons.
• A theory of dark matter. Our best guess is that
this will involve WIMPs: weakly interacting
massive particles.
• Supersymmetry: although there’s no evidence,
a lot of our physical theory would be
simplified if some of the standard particles
had “superpartners.”
Main Issue
Main issue: standard physics is either wrong or
only partly right. There are things (though we
don’t know what) that it does not talk about.
If the physical things are the things physics talks
about, then physicalism is false: not everything
is a thing physics talks about.
Second Pass
Suppose that we have an extremely long time to
investigate the universe, and that we’re all really
committed (and good) scientists, and that we
have unlimited funding and manpower for our
investigations. Eventually we come to a
satisfying physical theory that every one of us
agrees to. Call this the Ideal Final Theory.
Second Pass
A property or object is physical =def that
property or object appears in the Ideal Final
Theory.
Main Issue
Isn’t it possible that the Ideal Final Theory =
Subjective Idealism? If Subjective Idealism
counts as physicalism, then everything counts as
physicalism.
Hempel’s Dilemma
Either (a) we define physicalism as the thesis
that everything is something that current
physics talks about OR (b) we define it as the
thesis that everything is something that physics
should or would (in an ideal situation) talk
about.
Hempel’s Dilemma
If (a), then physicalism is probably false.
If (b), then physicalism is true, but trivially so:
it’s true no matter what the facts are.
False Dilemma
But it’s not true that those are the only ways to
define physicalism. In fact, those are bad
definitions.
Surely there are possible worlds that have
nothing but physical things in them, but don’t
have any of the things our world has in it.
Or Are There?
Or maybe there’s no sense to be made of a
physical/ non-physical distinction.