Philosophy: Carruthers

Front 1

Mind-Brain Identity Thesis

Back 1

Every mental state type is identical with a brain state type

Front 2

Causal Argrument for the Mind-Brain Identity Thesis

Back 2

1. Our mental states (thoughts, feelings, desires, etc.) often cause bodily movements.

2. Bodily movements are physical events

3. All physical events have physical causes.

4. If mental states cause bodily events, then mental states must be physical (they must be brain states)

Therefore: Mental states are identical with brain states

Front 3

Objection based on the certainty of the mental

Back 3

1. I can be absolutely certain about my own conscious experiences of my mental states.

2. I cannot be absolutely certain about what is going on in my brain

Therefore: my mental states are not identical with brain states

Front 4

Mind-Brain Identity Theorist's Reply

Back 4

Leibniz's Law does not apply to intentional properties (properties having to do with the way in which a thing is represented (though about or known))

Front 5

Objection based on the privacy of the mental

Back 5

1. Conscious states are private to the person who has them (directly accessible to the person via introspection, but only indirectly accessible to others)

2. Brain states are not private, since others can have objective scientific knowledge of a person's brain states

Therefore: Conscious states (mental states) are not identical with brain states

Front 6

Mind-Brain Identity Theorist's Reply

Back 6

It mistakenly applies Leibniz's Law to an intentional property (a property having to do with the subject's mode of representing mental states as directly and immediately accessible via introspection)

Front 7

Objection based on the normativity (morally assessing something) of the mental

Back 7

1. Conscious states are appropriate objects of normative assessment (it is appropriate to make moral judgments about a person's conscious states)

2. Purely physical states (brain states) are not appropriate objects of normative assessment.

3. Therefore: Conscious states (mental states) are not identical with brain states.

Front 8

Objection based on qualia (inner feelings)

Back 8

1. Experiences have distinctive qualitative feels (what it feels like to experience sadness)

2. Distinctive qualitative feels are not attributable to brain states (ex: serotonin levels aren't "cheerful")

Therefore: Experiences (mental states) are not identical with brain states

Front 9

Mind-Brain Identity Theorist's Reply

Back 9

The qualitative feel of an experience is not a property of the experience. Rather, the qualitative feel of an experience just is the experience itself. Experiencing sad feelings is no different from feeling sad. So the "Qualia Objection" fails to show that experiences have properties that brain states lack.

Front 10

Objection based on spatial position of physical objects

Back 10

1. All brain states have spatial location.

2. States of consciousness (mental states, such as beliefs, desires, feelings, etc.) do not have spatial location

Therefore: States of consciousness (mental states) are not identical with brain states)

Front 11

Mind-Brain Identity Theorist's Reply:

Back 11

States of consciousness (thoughts, for example) do have location. Thoughts are events, and these events take place at the exact location where the thinker is (in a particular region of the thinker's brain). As we gain a better understanding of how the brain works to produce thoughts, we will gain a better understanding of exactly where the thoughts and feelings occur in the brain.

Front 12

The Knowledge Objection

Back 12

1. Complete knowledge of the brain and central nervous system does not give us knowledge of what experiences feel like.

2. If experiences (mental states) were identical with brain states, then complete knowledge of the brain would yield complete knowledge of what experiences feel like.

Therefore: Experiences (mental states) are not identical with brain states)

Front 13

Mind-Brain Identity Theorist's Reply

Back 13

This argument trades on the ambiguity of the word "knowledge". "Knowledge" can mean "knowledge of the facts". This sort of knowledge is expressed by propositions (ex: serotonin and dopamine are neurotransmitters). Neuroscientific knowledge is factual or propositional knowledge. But the word "knowledge" can also refer to "recognitional" knowledge. This latter type of knowledge involves having practical skills, not knowing facts. Knowing what an experience feels like is not propositional knowledge, it is recognitional knowledge. Recognitional knowledge of feelings involve being able to recognize sad feelings and differentiate them from angry feelings. This sort of recognitional ability is a skill. Mind-Brain Identity Theory does not imply that complete propositional knowledge of how your brain works will make you better able to recognize and identify your feelings.