Determinism, Free Will, and Quantum Physics, Part 2

A New DevelopmentWerner Heisenberg,

1901-1976The 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 ObjectionYes, 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 ResponseBut some ordinary-size

structures can amplify quantum indeterminism

Example: a Geiger counterAnother 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


Special Status G. W. F.

Hegel, 1770-1831


Special Status Gottlob

Frege, 1848-1925


Special Status Ludwig

Wittgenstein, 1889-1951


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


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


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


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


Materialism says: the mind does have only material conditions

therefore it can be explained in purely material terms


Dualism says: the mind cannot be explained in purely material terms

therefore it must have some non-material enabling conditions


But a cube’s geometrical properties are not additional physical components alongside mass and chemical composition …


Mental phenomena are not non-material 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


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


Free will “software” can only run on indeterministic “hardware”

But the hardware is only an enabling condition, not a constitutive condition, of the software


But how do we make the quantum events happen?

By exerting a mysterious soul-force on our component particles?


No. Free will is not an additional enabling condition – it’s what gets enabled.

Our free choices don’t interfere with physical law.


Physical law determines only the probabilities of quantum events

Our free choices don’t alter those probabilities


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


But how do our free choices “make the quantum events happen”?

By exerting a spooky soul-force?


No. Can you move an atom without using special equipment? Yes. Just move your hand.


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

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Determinism, Free Will, and Quantum Physics, Part 2