Stare at center of left frame for 1 min., then at right

The Identity Theory J.J.C. Smart Australian philosopher,

the Identity thesis Mental events, states and processes are (literally identical to) physical events, states and processes. Mental events, states and processes are (literally identical to) physical events, states and processes. Every mental event = some physical event. Every mental event = some physical event. Every mental state = some physical state. Every mental state = some physical state. Every mental process= some physical process. Every mental process= some physical process.

(The most a Dualist could say is) M ental events, states and processes are CORRELATED WITH physical events, states and processes. M ental events, states and processes are CORRELATED WITH physical events, states and processes. Every mental event is correlated with some physical event. Every mental event is correlated with some physical event. Every mental state is correlated with some physical state. Every mental state is correlated with some physical state. Every mental process is correlated with some physical process. Every mental process is correlated with some physical process.

Empirical discovery Water = H 2 O The stuff we've been drinking for thousands of years known as water turned out to be molecules of hydrogen oxide. The stuff we've been drinking for thousands of years known as water turned out to be molecules of hydrogen oxide. Strokes turn out to be, not God striking a person, but blood vessels bursting in the brain and causing lots of damage. Strokes turn out to be, not God striking a person, but blood vessels bursting in the brain and causing lots of damage.

Lightning = electrical discharge The optical phenomenon known as lightning we've seen for thousands of years turned out to be electrical discharge due to ionization of clouds of water vapor in the atmosphere.

Similarly Our sensations, emotions, beliefs and perceptions turn out to be brain events/states--contrary to what the ancient Egyptians thought. When they mummified someone, they threw out the useless brains, and carefully wrapped up the heart and put it back in the chest.

Pros No interaction problem whatsoever; No interaction problem whatsoever; No problem of other minds; No problem of other minds; Explains why Neuroscience is so important to mental states. Explains why Neuroscience is so important to mental states. Jives nicely with the current physicalism in science, which looks for and finds unbroken chains of physical and biochemical causes. Jives nicely with the current physicalism in science, which looks for and finds unbroken chains of physical and biochemical causes.

Occam’s Razor Identity Theory vs. Dualism Need only one substance Need only one substance Need only neuroscientific explanations Need only neuroscientific explanations Need two substances Need neuroscientific explanations plus causal explanations that explain how exactly mental phenomena (if they are non-physical) cause physical phenomena, and vice versa.

Objection #1 (that Smart considers) Any illiterate peasant can talk perfectly well about what he sees, how he feels, his aches and pains. He is directly and immediately aware of such things. Yet he may, like the Egyptians, know nothing about brain processes. Therefore, such conscious experiences cannot be brain processes.

Smart’s response The same sort of reasoning would show lightning isn’t electrical discharge. The same sort of reasoning would show lightning isn’t electrical discharge. Distinguish meaning from reference : Distinguish meaning from reference : “the Georgetown alumnus married to Hilary Clinton” does not mean “the 42 nd President of the US” yet both refer to Bill Clinton “the Georgetown alumnus married to Hilary Clinton” does not mean “the 42 nd President of the US” yet both refer to Bill Clinton “The morning star” means the heavenly body near the horizon in the morning; “ the evening star” means …Yet it was discovered 6 th C. BC by Pythagoras that both refer to Venus. “The morning star” means the heavenly body near the horizon in the morning; “ the evening star” means …Yet it was discovered 6 th C. BC by Pythagoras that both refer to Venus.

Objection #3 Even if there aren’t any irreducibly psychic processes, there are irreducibly psychic properties— such as yellow— yellowness of an after-image. [Think sense datum.] Philosophers call this a Quale; ( plural is Qualia) or a raw feel. Even if there aren’t any irreducibly psychic processes, there are irreducibly psychic properties— such as yellow— the yellowness of an after-image. [Think sense datum.] Philosophers call this a Quale; ( plural is Qualia) or a raw feel.

That is, A sensation (or perception) cannot be a brain process, since it has a phenomenal property (how it seems to us) (a quale) not possessed by brain processes—for example, the phenomenal property of the yellowness of the after-image, for example.

Smart’s response What is it to say that something is yellow? It means something like “a normal percipient would not easily pick it out of a clump of these petals:

(Smart tries to “analyze away” the Quale) When a person says they see a yellow after- image, they are saying something like: “ There is something going on which is like what is going on when I have my eyes open, am awake and am looking at this figure.”

Objection #4 When you stare at something purple for a while, after you stop you will experience a yellow after-image. The after-image is not in physical space; the brain process is. So the after-image is not a brain process. Response : misses the point, which is not that the after-image is a brain process, but that the EXPERIENCE of having one is. "There is, in a sense, no such thing as an after- image...”

Objection #6 Sensations are private--can only be had by one person; brain processes are public (at least in principle). Moreover, Sensations are private--can only be had by one person; brain processes are public (at least in principle). Moreover, I cannot be wrong about whether I’m seeing a yellow after image; anyone can be wrong about whether some brain process is taking place. Therefore, sensations are not brain processes. I cannot be wrong about whether I’m seeing a yellow after image; anyone can be wrong about whether some brain process is taking place. Therefore, sensations are not brain processes.

Smart’s response “The language of introspective reports has a different logic from the language of material processes. Until the brain- process theory is much improved and widely accepted there will be no criteria for saying ‘Smith has an experience of such-and-such a sort’ except Smith’s introspective reports.” (151)

Notice the form of most of these objections: (1)There are properties that mental events/states/processes have that brain events/states/processes do not. (1)There are properties that mental events/states/processes have that brain events/states/processes do not. (2)If X & Y do not have the same properties, then X ≠ Y. (2)If X & Y do not have the same properties, then X ≠ Y. (3)Mental events/states/processes are not brain events/states/processes. (3)Mental events/states/processes are not brain events/states/processes.

Premise (2) is Leibniz’ Law Recall that this principle does not apply to intentional properties, like Jocasta's property of being such that Oedipus wants to marry her (because Jocasta = Oedipus's mother, yet O wants to marry Jocasta, but does not want to marry his mother.) So this sort of argument, to be sound, must avoid using intentional properties. So, for example, being such that I can be wrong about it sounds like an intentional property. Think Freud.

Objection #7 7) I can imagine myself turned to stone and yet having images, aches, pains and so on. (Response: "I can imagine that the electrical theory of lightning is false, that lightning is some sort of purely optical phenomenon.")

Nice neuroscience lecture on how mind-brain works A A A A