A New Development
Werner Heisenberg,
1901-1976
The fundamental laws
of quantum physics
are probabilistic
Physics is not
deterministic!
Arthur Eddington, 1882-1944
We’re composed of
matter that obeys
physical laws
But the movement of
fundamental particles
is not deterministic
So we can have free
will after all!
So Epicurus Was Right!
“If an atom were
always carried along
by natural necessary
force, nothing would
be up to us, since the
mind would be
moved in whichever
way its atoms were.”
Determinist Objection
 Yes,
quantum physics is indeterministic
at the microscopic level
 But it’s fairly deterministic at the level of
ordinary objects
 Quantum effects mostly cancel each
other out at that level
 The motion of each particular particle is
uncertain, but not of an entire object
Indeterminist Response
 But
some ordinary-size structures
can amplify quantum
indeterminism
 Example: a Geiger counter
 Another example: the human
brain?
Determinist Counter-Response
 But
do quantum events cause our
choices, or do our choices cause the
quantum events?
 If quantum events cause our choices,
then we’re still being determined by
something outside our control.
 If our choices cause quantum events,
how? Aren’t we back to the spooky
unmeasurable soul-force?
Are Reductive Materialism & Dualistic
Spookiness Our Only Options?
It’s often said that the tendency
of scientific thought in the past
500 years is more and more to
undermine the special status
of human beings …
Copernicus and Galileo
Help! Our
planet isn’t at
the center of
the universe!
Charles Darwin
Help! We’re
descended
from apes!
Karl Marx
Help! We’re
controlled by
economic
forces!
Sigmund Freud
Help! We’re
controlled by
our
subconscious!
But Parallel Philosophical Trends Have
Been Reasserting Our Special Status
Immanuel Kant,
1724-1804
But Parallel Philosophical Trends Have
Been Reasserting Our Special Status
G. W. F. Hegel,
1770-1831
But Parallel Philosophical Trends Have
Been Reasserting Our Special Status
Gottlob Frege,
1848-1925
But Parallel Philosophical Trends Have
Been Reasserting Our Special Status
Ludwig
Wittgenstein,
1889-1951
But Parallel Philosophical Trends Have
Been Reasserting Our Special Status
John McDowell,
b. 1942
According to Post-Kantian Philosophy:
 The
truths of logic and mathematics do
not depend on the nature of matter
 So logical relations cannot be explained
in purely physical terms
 So nothing capable of grasping logical
relations can be explained in purely
physical terms either
 So human beings cannot be explained
in purely physical terms
A Crucial Distinction
Enabling
conditions:
those that make something’s
existence possible
Constitutive conditions:
those that determine
something’s identity
What makes something a cube?
What composition,
temperature, etc.,
are needed to keep
a cubical shape?
 A question for
physicists and
chemists
 A question about
enabling conditions
What makes something a cube?
What properties must
a thing have to
count as being a
cube?
 A question for
geometers
 A question about
constitutive
conditions
According to Post-Kantian Philosophy:
 Geometry
cannot be reduced to
physics and chemistry
 Constitutive conditions cannot be
reduced to enabling conditions
 Logic and psychology deal with the
constitutive conditions of mind
 Neurophysiology deals with the
enabling conditions of mind
According to Post-Kantian Philosophy:
The dualists are partly right:
the mind cannot be explained in
purely material terms
 The materialists are partly right:
to explain the mind we do not
need to posit a non-material
component

According to Post-Kantian Philosophy:
Both materialism and dualism
make the same mistake
 Both assume that if the mind
has only material enabling
conditions, then it can be
entirely explained in material
terms

According to Post-Kantian Philosophy:
Materialism says:
 the mind does have only
material conditions
 therefore it can be explained in
purely material terms
According to Post-Kantian Philosophy:
Dualism says:
 the mind cannot be explained in
purely material terms
 therefore it must have some
non-material enabling conditions
According to Post-Kantian Philosophy:
But a cube’s
geometrical
properties are not
additional physical
components
alongside mass
and chemical
composition …
According to Post-Kantian Philosophy:
Mental phenomena are not nonmaterial enabling conditions in
addition to the mind’s material
enabling conditions
 Mental phenomena are not
enabling conditions at all, they’re
constitutive conditions

So Are Reductive Materialism &
Dualistic Spookiness Our Only Options?
No!
How does this help with free will?
 Creatures
with minds are made of
matter
 Our physical properties have to be
compatible with our mental
properties
 Our physical properties do not have
to explain our mental properties
How does this help with free will?
 Indeterministic
quantum events
make free choices possible
 They’re enabling conditions of our
free choices
 But indeterministic quantum events
do not cause or explain our free
choices
How does this help with free will?
 Free
will “software” can only run on
indeterministic “hardware”
 But the hardware is only an
enabling condition, not a
constitutive condition, of the
software
How does this help with free will?
But
how do we make the
quantum events happen?
By exerting a mysterious soulforce on our component
particles?
How does this help with free will?
No.
Free
will is not an additional
enabling condition – it’s what
gets enabled.
Our free choices don’t interfere
with physical law.
How does this help with free will?
Physical law determines only
the probabilities of quantum
events
 Our free choices don’t alter
those probabilities

How does this help with free will?
Physical law determines how
likely the quantum events are
 We don’t make the enabling
conditions more likely
 We just make the enabling
conditions happen

How does this help with free will?
But how do our free choices
“make the quantum events
happen”?
 By exerting a spooky soulforce?

How does this help with free will?
No.
 Can you move
an atom without
using special
equipment?
 Yes. Just move your hand.

How does this help with free will?
We don’t cause quantum events
by exerting a spooky soul-force
 We cause them simply by
performing the actions which
have those events as underlying
enabling conditions

And so the debate continues …
The End