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1. The Flight from Dualism |
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The
Issue Between Dualism and Materialism Preliminary
characterization of the difference between dualism and materialism A
natural distinction between kinds of things: height, weight, colour,
genome, etc. vs. emotional state, thoughts, experiences, etc. Call
the former physical facts and the latter mental facts. Dualism
says full understanding of mental facts requires different elements than
will do for physical. Materialism
denies this. Everything is explicable in terms of matter.
Idealism Idealism
says everything is explicable in terms of mentality. Materialism and Idealism are both kinds of Monism Materialism is the consensus view today – but has
problems that keep other options alive Some
of the classic arguments for dualism Leibniz’s law and the arguments for dualism Leibniz’s
Law = indiscernibility of identicals If
x = y then any proprty of x is a property of y. Apply this to physical and
mental items. An empirical response We aren’t sure
that mental items don’t have those physical properties. An odd-seeming
truth is still true. Compare mass of light, movement wrt ground, shape of
space, etc.
What
explains the dualist intuition? Sensations
and physical states just seem very different. That’s how we came up with
the division What
explains away the dualist intuition? Sensations and physical states seem very different. But you are comparing your feelings on contemplating
sensation vs when contemplating the brain state of one having the
sensation. Those feelings are different so the two objects must be
different. Wrong. The same thing may cause different effects if
they are caused by it in different ways. A
Cartesian argument You
can doubt your body, but not your mind; therefore body != mind. A
reply to the cartesian argument There is a problem of opacity here. Doubt is a propostional
attitude, and therefore creates an opaque
context. You can’t substitute coreferential terms into an
opaque context salva veritate. Ortcutt = tallest spy. I can doubt Ortcutt is a spy,
but I can’t doubt the tallest spy is a spy. Machines
and the flexibility of rationality For
a materialist, we are machines, and machines are inflexible/determined
whereas we are not. A
response: determinism is wrong, the physical world is indeterministic. A
counter-response: ‘randomness’ won’t get us the rational flexibility
that we think we have. Would
ectoplasm help? The dualist doesn’t deny we are machines – just
that the machines are purely physical. We could be part ectoplasmic
machines. Would that help explain how we can be rationally flexible? No. Nowadays we know anyway that machines aren’t
necessarily that inflexible An
argument from mathematical logic Gödel’s Theorem:
Any sound formal system with arithmetic has theorems that are true but not
provable in that system. If
we are machines, then we are a formal system – S. If we are S, then
there are theorems T which we know are true but not provable in S. But we
can find these T. So we know they’re true. So we are stronger than S. So
we are not machines. QED. A
reply to the Gödel argument It’s not clear that we can find such T. It’s not clear that
S is sound. We have no idea how complex S might be. Two
kinds of dualism Substance
dualism and attribute dualism 1.
Substance dualism: physical and mental are different substances.
(E.g. Descartes.) 2.
attribute dualism: physical and mental are different kinds of properties
A
famous problem for substance dualism The nature of mental substance is mental activity.
What happens when no mental things are occurring in mental-us? Do we go
out of mental existence? No substance can exist without a nature. Response 1: we never stop being mental. Seems
unlikely. Response 2: there’s more to the non-physical than
just the mental. What? Upshot is that dualists these days tend to be
attribute dualists. The
causal problem for dualism There
is a causal link between mental states and behaviour Intentions
lead to actions, etc. What do mental attributes contribute to actions? Epiphenomenalism:
they have no causal role. (They are caused but cause nothing.) So
intentions don’t causally lead to actions. Who can believe this? The
evolutionary objection to epiphenomenalism
Mentality evolved. How could it be selected for if it has no causal
effect?
It could be that mentality is just a byproduct of really adaptive
features. The
epistemological objection to epiphenomenalism There can be no physical effect of epiphenomenal
attributes – so we have no good evidence for their existence. How can we remember them? If forming memories depends
upon changing physical states in the brain, and epiphenomena can’t
affect those states, then we can’t remember them. Parallelism Physical states don’t causally affect mental, nor
mental physical. Leibniz: there’s a pre-established harmony that
simulates causal connection. Dualist
interactionism Dualists
have to believe that the physical world is not causally closed, so that physical properties can give rise to
non-physical ones, and v.v. The
physical world is closed We have every reason to believe the world is
causally closed. Some
responses for the dualist Action
is different from behaviour Behaviour
(eg. your arm rises) is different from action
(eg. you signal a taxi.) Dualists
may say that the former is explicable physically, but not the latter. Yet
actions involve behaviours, so this won’t work. Overdetermination Overdetermination:
two occurrent causes are both sufficient for an event. (E.g. bullet OR
fall à death.) Do
mental and physical properties overdetermine
behaviours? Causal
explanations tend to exclude each other Eg. Rock wants to be near more rock is displaced
by rock is drawn by gravity. Pre-emptive
overdetermination If X would kill but Y kills first then X is pre-empted
by Y. But if mental is pre-empted by physical then mental
does nothing Partial
overdetermination Eg. bullet causes death, fall causes death. But
bullet also makes a hole and a fall makes broken bones. The effects in
total are different. Overdetermination is only of certain parts of the whole effect. Impossibility
of full overdetermination A dualist needs full overdetermination (any effects
not also caused by the physical factors are a problem) – but there are
no examples of this. Why suppose it is possible? Sequential
overdetermination Non-physical factors explain why the brain states
causing behaviours are the way they are. But to explain A as caused by X (physical) caused by
Y (physical) caused by … caused by Z (non-physical), just means that the
point we need to explain is moved. Overdetermination
by the non-distinct Eg. Death caused by heart attack / death caused by
organ failure. They are not distinct causes. As long as we can reduce one to the other there is no
problem – but the dualist denies this for M/P so the problem remains Indeterminism Quantum
mechanics suggest the world is indeterminate. Can mental facts affect
probabilities for physical facts? If
so then mental has an effect on the physical world. So world isn’t
causally closed. |