1. Test Recap Time
What does it mean to suggest that mental properties are emergent (3 marks)
Explain the criticism that whilst P-Zombies are conceivable, they may not be possible (5 marks)
Outline the knowledge argument and one possible response (12 marks)
Read through the feedback given on your test.
Pick a question to rewrite (green pens!).
Use your notes (from last lesson) and the feedback to help you construct the perfect answer.
Help people around you if they need it (and you have the correct information).

2. Homework
Read through the passage on the sheet. Identify: What problem Elisabeth has with the theory of Substance Dualism as put forward by Descartes. Why she suggests it is a problem (what reasoning she gives for her issue). Extension: Research and identify the answer that Descartes gives to this problem.

3. What problem Elisabeth has with the theory of Substance Dualism as put forward by Descartes.
Given that the soul of a human being is only a thinking substance, how can it affect the bodily spirits, in order to bring about voluntary actions?

4. Why she suggests it is a problem (what reasoning she gives for her issue).
The question arises· because it seems that how a thing moves depends solely on (i) how much it is pushed, (ii) the manner in which it is pushed, or (iii) the surface-texture and shape of the thing that pushes it. The first two of those require contact between the two things, and the third requires that the causally active thing be extended.
Your notion of the soul entirely excludes extension, and it appears to me that an immaterial thing can’t possibly touch anything else.

5. Extension: Research and identify the answer that Descartes gives to this problem.

6. Interactionism – What is it?
The idea that the mind and body interact.
A mental act or volition causes physical actions to occur in my body.
Similarly physical actions and states in my body cause particular mental states to occur in my mind.
These mental states then cause me to form various other mental states / beliefs or further physical actions.
This is the most common way of seeing the different dualistic theories – known as interactionism.

7. Interactionism – Why Support It?
It just seems common sense! If I decide to reach out for my cup of tea then (under normal circumstances) my arm will move and my hand will grasp the handle. My mental act of volition seems to have caused a physical action to occur in my body.
This causal relationship also works in the other direction. If I sip my tea, the contact between the warm liquid, and the inside of my mouth causes various tea-like sensations to occur in my consciousness. Here, physical changes or events seem to have caused mental events.

8. Descartes Interactionism
For Descartes it was obvious that our mind and body interact constantly. We feel ourselves as a complete, embodied being rather than a separate mind and body. Although separate substances (for Descartes) the mind and body are in an “intimate union” ‘Nature also teaches me … that I am not merely present in my body as a sailor is present in a ship, but that I am very closely joined and, as it were, intermingled with it, so that I and the body form a unit.’
He even identified part of the brain he thought was responsible for this interaction – the pineal gland. A small organ right in the centre of the system.

9. “I further notice that the mind does not receive the impressions from all parts of the body immediately, but only from the brain. Or perhaps it does this even from one of its smallest parts, namely, from that in which the common sense is said to reside, which, whenever it is disposed in the same particular way, conveys the same thing to the mind, although meanwhile the other portions of the body may be differently disposed, as is testified by innumerable experiments which it is unnecessary here to recount.” - Descartes

10. Why might a ghost driving a car present a problem for dualism?
But… Some Issues…
Why might a ghost driving a car present a problem for dualism?

11. The A Priori Problem of Interaction
One problem for Descartes (and indeed any version of dualism) when it comes to interactionism is their apparent inability to explain how a non-physical mind can causally interact with a physical body.
Usually for two things to interact they must share at least one of the same properties (extension in space being the primary one). The mind and body do not have this similarity.

12. “Given that the soul of a human being is only a thinking substance, how can it affect the bodily spirits, in order to bring about voluntary actions? ... Your notion of the soul entirely excludes extension, and it appears to me that an immaterial thing can’t possibly touch anything else.” – Princess Elisabeth of Bohemia

13. One Possible Response:
Descartes responds by suggesting that the Princess has misunderstood how things move. She claims that for one thing to move another, they must touch each other. But Descartes points out that we can understand how the weight of a rock combined with gravity causes the rock to fall downwards without thinking that the weight actually pushes the rock. So we can understand the mind to affect the body in the same way – involving no surface to surface contact.

14. One Possible Response:
For Descartes the mind-body union is a “basic notion” and “should only be understood through itself.” By this he means we shouldn’t try and make sense of it through anything else. We certainly shouldn’t be assuming it is like the physical interactions we see in the world every day. But is this just a bit of a cop out?

15. An Unlikely Defence
One person who actually defends a causal interaction between the mind and body (somewhat surprisingly) is David Hume. He argues that we can only make judgements about what is causally related through empirical investigation. Simply identifying the properties of something is not enough.
Could you identify how this bread was caused just by looking at it’s properties?

16. Does this really explain anything though?
An Unlikely Defence
Instead we should just accept that there is a causal relation between the mind and body, because that is what we repeatedly experience. As long as we constantly experience a connection of will and actions, this is the only basis we have for assuming a causal connection.
Does this really explain anything though?

17. A Second Problem of Interaction
A secondary issue is to consider why a particular mind is linked to a particular body.
If minds have no physical location in space:
Why do we connect minds to a single body?
Why not someone else's body?
Why not multiple bodies?
If minds have no physical location in space it is unclear why they seem to follow around particular bodies.

18. Quick Questions What is interactionism?
Make sure you have these answers somewhere in your notes (if you’ve done the homework you may be able to skip some):
What is interactionism?
Outline the A Priori problem of interaction.
How does Descartes respond to these problems?
How does Hume answer the problem of interaction?
Why might the fact that my mind is connected to my body alone present a problem for interactionism?

19. The Empirical Problem of Interaction
The law of the conservation of energy
This scientific principle states that:
There is a transfer of energy from cause to effect
The total amount of energy in the universe always remains the same
Why does this present a problem for interactionist dualism?

20. The Empirical Problem of Interaction
The law of the conservation of energy
This scientific principle states that:
There is a transfer of energy from cause to effect
The total amount of energy in the universe always remains the same
Suppose that an event in a mind causes an event to occur in a body. According to 1 there is a transfer of energy, therefore the body gains energy. But the mind, having no physical characteristics cannot lose energy. So there is a gain in the total amount of energy in the universe, which violates 2. This also works for physical things causing mental.

21. The Empirical Problem of Interaction
The physical universe is a closed system.
In any closed system energy must be conserved.
Mind and body causally interact.
But causation involves a transfer of energy.
Therefore either the mind must be physical, or it must not causally interact with the body.

22. Possible Response: Redistribution
One possible response is to say that the mind does not inject new energy into the body but instead redistributes already existing energy. Our mind effectively “steers” how our body will make use of any pools of energy we have left.

23. Possible Response: Redistribution
But this seems to clash with the science again, energy can only be redistributed by using energy.
We don’t steer a car using only the power from the engine for example, we have to add energy to the steering wheel to turn it.
So if our mind does indeed steer our body, then it must use some energy (however small) to do so, but as a non-physical thing where is this coming from?

24. Possible Response: Cancellation
Interactionism could be defended by arguing that the overall amount of energy in the system can remain constant since the effects of mind and body on each other cancel each other out.
Perhaps when I add energy too my body through some act of mental volition, energy also escapes through some hidden wormhole thus keeping the amount constant.
But without proof to support this idea, or without some explanation as to why they should balance each other exactly, this solution seems more like wishful thinking than a solid response.

25. A Final Point
It’s worth remembering here that the criticisms covered today are not evidence against dualism as a whole, but evidence against there being a causal interaction between the mind and the body (interactionism). Accordingly there have been other suggestions as to the mental-physical relationship that we will cover next lesson.

26. Quick Questions Continued
Make sure you have these answers somewhere in your notes:
Why does what we know of physics present a problem for interaction?
Identify two ways a dualist who wants to support interactionism might respond to the empirical issue with interaction. Do these responses work? If not, why not?