1. Property dualism: objections
Michael Lacewing
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2. Substance and property dualism
Substance dualism: minds are not bodies nor parts of bodies, but distinct substances
Cartesian dualism: Minds can exist independent of bodies, and mental properties are properties of a mental substance
Property dualism: there is just one sort of substance, physical substance, but at least some mental properties are a fundamentally new kind of property that are not fixed by physical properties
Properties of phenomenal consciousness – qualia
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3. Rejecting physicalism
Physicalism: everything that exists is physical or depends on what is physical
The only kind of substance is physical
The only properties that are fundamental are physical properties – all other properties depend on physical properties
Property dualism: some properties of consciousness are not ontologically dependent on physical properties
There are natural laws that correlate mental properties with physical ones, but it is metaphysically possible for these correlations to be different
© Michael Lacewing

4. Mental causation Do mental properties have ‘causal powers’?
E.g. Do thoughts cause bodily movements and other thoughts?
Property dualism doesn’t face the problem that substance dualism does, because mental properties are properties of physical substance
But how do mental properties cause physical effects?
This is no objection: any fundamental causal relationship can’t be further explained (e.g. how does mass bend space?)
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5. Property dualism and science
Objection: if mental properties cause physical effects, this is incompatible with science, esp. neuroscience
We don’t have good evidence of this
Some interpretations of quantum mechanics support the idea that consciousness has effects
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6. Epiphenomenalism
It is appealing to think that every physical event has a sufficient physical cause
This is compatible with property dualism if mental properties make no causal difference to the world – epiphenomenalism
Physicalism is right about causation, but wrong about what exists
© Michael Lacewing

7. Counter-intuitive Objection: Epiphenomenalism is very counterintuitive
Reply 1: it is only some mental properties – qualia – that are epiphenomenal
Reply 2: it seems like mental states (e.g. pain) cause physical effects (e.g. crying) because a brain process causes both
So the mental state is correlated with the effect, but doesn’t cause it
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8. Natural selection
Objection: how and why would epiphenomenal properties evolve?
The traits that evolve are ones that causally contribute to survival and reproduction
Reply: epiphenomenal mental properties are by-products of traits (brain processes) that make a difference to survival
Not all properties are selected for, e.g. a polar bear needs a warm coat, and this turns out to be heavy, but the heaviness doesn’t contribute to survival
It’s just a fundamental law of nature that some brain processes are correlated with consciousness
© Michael Lacewing

9. An objection from introspection
I know I am in pain, because my belief that I am in pain is caused by my pain.
If epiphenomenalism is true, my pain causes nothing.
If epiphenomenalism is true, I will believe that I am in pain if my brain processes are the same, even if I am not in pain.
So if epiphenomenalism is true, my belief that I am in pain is unreliable, and not knowledge.
© Michael Lacewing

10. Reply Knowledge doesn’t require direct causation
Suppose the brain state that causes pain also causes the belief that I am in pain
Then I wouldn’t (normally) have the belief without the pain – so my belief is reliable
So I know when I’m in pain
© Michael Lacewing

11. A ‘category mistake’
Category mistake: To treat a concept as belonging to a different logical category from the one it actually belongs to
E.g. Oxford University; team spirit
Ryle: Substance dualism wrongly thinks that the mind is another ‘thing’
It is not a distinct, complex, organised unit, subject to distinct relations of cause and effect (to lose your mind and lose your keys is not to lose two things!)
Mental concepts (of ‘states’ and ‘processes’) do not operate like physical concepts
The ‘para-mechanical hypothesis’:
since physical processes can be explained in mechanical terms, mental concepts must refer to non-spatial, non-mechanical processes
This is a category mistake
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12. A ‘category mistake’
This applies to property dualism – it thinks of mental properties as part of the same metaphysical framework as physical and functional properties, only different
Experiences are not a ‘something’ with peculiar properties of ‘what it is like’
‘What it is like’ to see red is given by describing what we see when we attend to a red object
‘Red’ is the colour of the object, not a property of experience
Differences between experiences (‘what it is like to see red is different from what it is like to see blue’) are simply differences between physical objects
© Michael Lacewing