Mind, Body & Soul

• Plato's dualism

  The view that the mind/soul and the body are different types of thing/existence
• Plato

  • Thinks the world of forms is the real world and this physical world, including our body, is not the real world
  • Believes we are really a soul, not a body
• Plato's argument from recollection

  1. We have ideas of perfect things like a perfect circle or perfect justice

  2. We have never seen a perfect circle or perfect goodness

  3. We must have got these ideas from the world of forms where there are perfect forms of circles and goodness

  4. There must be a part of us - our soul - which was in the world of forms before we were born
• • Arguably there is no such thing as perfect goodness – what someone thinks is good depends on their culture.
  • Perfect goodness will mean different things to different people.


  Critique of The Argument From Recollection
• • Hume claims we can actually invent the idea of perfection ourselves – even though we haven’t experienced it.
  • We take our idea of imperfect beauty or imperfect circles that we have experienced, and simply imagine them without the imperfection – to arrive at the idea of perfection. 
  • So, just because we haven’t experienced perfection, doesn’t require the existence of a soul or realm of forms to explain how we got the idea. 
  • So, Plato’s argument for the soul seems to fail


  Hume’s Critique of The Argument From Recollection
• Aristotle’s view of the soul

  • Aristotle is a materialist – thinks only one type of thing exists – material/physical things. 
  • But he still believes in a soul as part of our material body – the soul is the ‘form’ of the body.
  • The soul is what gives our body rational thought.
  • It’s not a separate thing to our body – it is the form of our physical body.


  What is Aristotle?

  What does he think only exists?

  What is the soul for our body?

  Does Aristotle believe our soul is separable?
• • Stamp in wax analogy – the body is like wax and the soul is like the imprint in wax left by the stamp. 
  • The imprint is not a separate unique thing itself – it is just the form the wax has. Same goes for the soul.


  Aristotle’s Example

  What is the body like?

  What is the soul like?

  True or false - the imprint is not a separate unique thing itself: it is just the form the wax has
• Modern scientists would reject Aristotle’s theory. They would say the body is just material structure – there it has no ‘form’.

  • Rational thought is just caused by brain processes, we don’t need the idea of form, so we don’t need the idea of a soul.


  Modern science’s rejection of formal causation

  What would modern scientists say about the body?

  What is rational thought caused by?

  What we don’t need the idea of?
• Descartes’ view of the soul

  • Descartes thought the mind and soul were the same thing.
  • Descartes was a dualist – a substance dualist – he thought that the mind and body were distinct substances – meaning distinct fundamental types of existence.
• • The Indivisibility argument
  • P1. Physical substance is divisible (since it’s extended).
  • P2. The mind is indivisible (since it’s non-extended).
  • P3. Leibniz’ law is that identical things must have the same properties.
  • C1. The mind therefore cannot be identical with any physical substance, such as the body.
• Leibniz’ law:

  Identical things must have the same properties. The physical has the property of being divisible but the mental does not. If the body and mind were identical, then that one identical thing would be both divisible and indivisible, which is impossible. Therefore, the mind and body are not identical.


  Leibniz’s Law
• Criticism of Descartes


  • The mind can be divided into feelings, thoughts, memories, etc.
  • Modern evidence of split-brain patients
• Split-brain patient Criticism

  • The human brain has two hemispheres which are connected by a single band of neurons
  • The right hemisphere controls the left arm, and the left hemisphere controls the right arm
  • Doctors sometimes cut the connecting neurons as a treatment for epilepsy, separating the two hemispheres
  • In patients who have undergone that procedure, it appears that their mind has been divided into two
• A stronger criticism of Descartes is the modern evidence of split-brain patients
• Descartes 2nd Argument: Conceivability


  • Things that are identical cannot be imagined as separate – e.g. you can’t imagine a triangle separate from three sides.
  • Descartes says he can imagine the mind without a body.
  • E.g. imagine being a ghost walking through walls
  • If we can imagine the mind without the body, that shows it’s possible for the mind to exist without the body.
  • So, the mind cannot be identical to the body.
  • So, the mind and body are separate.
• Category error

  Talking about a concept as if it belonged to a category that it doesn't belong to
• Descartes' arguments


  Saying the mind/soul is not like a physical thing, it's not divisible
• Descartes concludes


  The mind must be in the category of 'non-physical things'
• Ryle objects that Descartes assumes the mind must be a 'thing'
• Ryle's view


  The mind is not a thing, it is a set of dispositions towards certain behaviours
• Ryle's 'soft' behaviourism


  Language about the mind is only valid when explained in terms of behavioural dispositions
• Ryle rejects talking about the mind as if it were a 'thing' as unscientific nonsense
• Ryle's point


  They have mistakenly put 'university' into the category of 'individual buildings' when really the university is in the category of 'collection of buildings'