Philosophy of Mind: The Mind-Body Problem

1. Philosophy of Mind: • The Mind-Body Problem PHIL 101 – Fall 2009 Instructor: Dan G. Jenkins TA: Paul J. Kelly

2. The Ontological Problem • What is the nature of mental states and mental properties? • Main solutions: • Dualism • Materialism

3. Main Points of Last Class Dualism • What is dualism? • What is the difference between substance dualism and property dualism? • What is the Interaction Problem?

4. Main Points of This Class Materialism • What is materialism? • What are the three main types of materialism? • How are they different from one another?

5. Opening Discussion Questions • Could a computer ever become conscious? • Could you ever directly experience another person’s pain? • What makes one theory better than another? • What is an umbrella made of?

6. What is Materialism? • Materialism is the view that only the physical exists. • Materialists claim that minds are entirely physical. • Materialists believe that non-physical minds do not exist.

7. Types of Materialism • Type-Identity Theory • Functionalism • Eliminative Materialism

8. Type-Identity Theory • Each type of mental state is identical to some type of physical state in the nervous system. (types of mental states = types of brain states) • Other examples of theoretical identities: • Sound = longitudinal compression waves • Light = electromagnetic radiation • Heat = mean molecular kinetic energy

9. Arguments in Support of Type-Identity • Physical origins of individuals • Physical origins of species • Neural dependence

10. Arguments from Physical Origins • Physical origins of individuals • We can adequately describe the development of an individual from the moment of conception to birth without an appeal to the non-physical. • Physical origins of species • We can adequately describe the development of species from the first single celled organism to complex multi-celled organisms without an appeal to the non-physical.

11. Argument from Neural Dependence • Empirical research has shown the neural dependence of all known mental phenomena. • This is precisely what one should expect if the identity theory is true (but is also consistent with property dualism).

12. Argument Against Type-Identity • Multiple Realizability: • It seems that a single mental state can be realized by a variety of different physical states. • What is important is not the material a creature is made of, but the functions that material sustains. • The identity theory is going to be hard pressed to produce a one-to-one match-up between types of mental states and types of physical states.

13. Functionalism • Mental states are functional states, and are defined by their causal relations to other functional states, sensory inputs, and behavioral outputs. • Consequently, whenever a functional state exists the corresponding mental state must also exist.

14. Arguments Against Functionalism • Inverted Spectrum • Absent Qualia

15. Inverted Spectrum • We can imagine two individuals with inverted spectrums but who remain functionally equivalent. • Functionalism would say both are in the same mental state, but we can imagine that they aren’t.

16. Absent Qualia • What would happen if everyone in China was given a walkie-talkie and was asked to simulate the action of one neuron in a conscious brain? • Would this functional arrangement have a mind and conscious experiences?

17. Types of Materialism • Type-Identity Theory • Functionalism • Eliminative Materialism

18. Inter-theoretic Reduction/Elimination • When one theory becomes outdated and a new one replaces it, the concepts from the first theory are either reduced or eliminated. • Some examples of elimination are: • Caloric fluid => Molecular Kinetic Theory of Heat • Phlogiston => Oxidization • Crystalline Sphere => Modern Astronomy • Demonic Possession => Schizophrenia Complete Reduction Complete Elimination

19. Current Conception of the Mind • Thoughts • Beliefs • Fears • Hopes • Desires • Sensations • Memories • Emotions • The will • Imagination • The unconscious • Raw experience (qualia)

20. Folk-Psychology • The pre-scientific theoretical framework that seeks to describe human psychology. • Folk psychology embraces everyday concepts like beliefs, desires, fears, hopes, etc.

21. Folk-Psychological Anomalies • Split Brain Patients • Phantom Limbs • Blindsight and Blindness Denial

22. Anomaly #1: Split Brain Patients • When an image is displayed to the right of the patient’s visual field he can report what he sees. • When an imagine is displayed to the left of the patient’s visual field, he reports that he sees nothing, but can reach out and grab the item from a collection of objects. • Why is this?

23. Split Brain Explanation • Visual information projected on the right side of the screen goes to the patient's left hemisphere, which controls language. • Visual information projected on the left side of the screen goes to the patient's right hemisphere, which does not control language, but excels at nonverbal and spatial tasks.

24. Split Brain Explanation • The physical act of severing the corpus callosum resulted in a mental division in the person’s mind.

25. Anomaly #2: Phantom Limbs • An individual with an amputated left arm says his phantom hand is painfully clenched and won’t release. • He also states that he can feel movement on his phantom hand when touching his left cheek. • Why is this?

26. Phantom Limb Explanation • Our internal body image does not faithfully represent external locations and proportions. • When the neurons representing his left hand stopped receiving input, the neurons representing his face invaded the hand area causing the overlap in sensations.

27. Phantom Limb Explanation • Furthermore, the pain from the clenched phantom limb is the result of the brain not receiving the proper feedback from the limb informing it that the hand had relaxed. • Utilizing what we now know about visual feedback and pain, the patient’s clenched phantom hand can be released by using a “mirror box.”

28. Anomaly #3: Blindsight/Blindness Denial • Blindsight • Having no conscious awareness of an object, but still being able to describe it. • Blindness Denial • Being blind, but maintaining that one can still see. • Why is this?

29. Blindsight/Blindness Denial Explanation • Blindsight • There are actually two main visual pathways in the brain. One is associated with conscious awareness while the other is associated with unconscious reflexes (usually focusing on movement and location). • Blindness Denial • The main language area connected with the visual cortex has become disconnected and receives no information regarding vision. Consequently, the language area confabulates reasons why it makes mistakes and refuses to accept that it is blind. Even though the brain cannot see, it does not know that it cannot see.

30. What do these examples tell us? • Our commonsense intuitions concerning the mind aren’t infallible. • Perhaps as we come to learn more about the brain we will be forced to modify our conception of the mind, the self, consciousness, etc.

31. Eliminative Materialism • Our ordinary, common-sense understanding of the mind is deeply mistakenand some or all of the mental states in our folk-psychologydo not actually exist. • As neuroscience matures we might want to reconceive our mental experiences in material terms.

32. Arguments for Eliminative Materialism 1) Failures of Folk-Psychology 2) The Fate of Earlier Folk-Theories

33. Failures of Folk-Psychology • Folk-psychology is unable to tell us: • Why we sleep, how we learn, how we remember, why there are differences in intelligence, the cause of mental disorders and how to cure them, etc. • However, recent work in the neurosciences has shed light on all these issues.

34. The Fate of Earlier Folk-Theories • Folk-theories concerning light, the nature of fire, the cause of tides, planetary motion, etc. all turned out to be radically mistaken. • “It would be a miracle if we had got [folk-psychology] right the very first time, when we fell down so badly on all the others.”

35. Arguments Against Eliminative Materialism • Introspection • Exaggerates the Defects in Folk-Psychology

36. Argument from Introspection Argument: • Pains, beliefs, desires, and fears obviously exist. Therefore eliminative materialism must be false. Objection: • The eliminative materialist isn’t arguing that such experiences don’t exist, but that the categories we currently apply to them are non-referential. • When we stopped believing in the crystalline sphere the stars didn’t disappear. We just came to understand our visual experiences through a more accurate conceptual framework.

37. Exaggerates the Defects in Folk-Psychology Argument: • While folk-psychology may have its faults, it’s still pretty good at explaining human behavior and intentions. Response: • If this is true, then perhaps only some concepts will be eliminated, while others will be successfully reduced. • Only empirical research will be able to tell which concepts will survive and which won’t. Complete Reduction Complete Elimination

38. Questions?