Substance Dualism

Substance Dualism

1. There are two ontologically distinct substances that make up a human being: mind and body

   • mind is a substance that possesses mental properties
     • beliefs
     • memories
     • thoughts
     • emotions
   • body is a substance that possesses physical properties
     • height
     • mass

2. Arguments for Dualism

   • doubt
     • I cannot doubt I am a thinking thing
       • cogito ergo sum
       • But I can doubt the existence of my body
         • Leibniz' Law: what I cannot doubt cannot be the same as what I can doubt
           • Therefore mind and body cannot be the same
     • other differences between mental and physical properties
       • mental states are private
       • mental properties possess qualia - they are subjective
         • what is subjective cannot be reduced to what is objective
   • Indivisibility
     • body is divisible - mind is not
       • body has the attribute of extension, and what is extended in space is divisible
       • mind is non-extended and does not physically exist in space therefore it is indivisible
         • Descartes: "it is one and the same mind that wills, and understands and has sensory perceptions"
           • Is Descartes simply being misled by the seductive grammatical use of 'I' to describe a unitary individual?
             • Counter to indivisibility
               • division of the unconscious and the conscious
               • multiple personality disorders

3. Arguments against Dualism

   • Mind-body problem
     • human experience is of one unitary embodied mind
     • substance dualism cannot give an adequate account of mental causation
     • Counter
       • Descartes would argue the relationship between mind and body is merely causal
         • the mind does need the brain to function but that does not mean it is not logically distinct from it
           • analogy - the body needs oxygen to function yet the body is a completely separate substance from oxygen
   • Leads to Solipsism
     • Mental substances are private and therefore could be different from anyone else's
     • Experience refers solely to my experiences
     • How can I know anyone else has a mind if I cannot have any phenomenological experience of other people's mental states
     • Counter
       • Argument from analogy
         • i have a mind, by analogy, its logical to think other people do to
       • experience presupposes other minds
         • it is human nature to observe behaviour and attribute mental states
         • I couldn't have thoughts without other minds existing