INTRODUCTION Identity Theory

The Identity Theory The Identity Theory: Mental states identical to physical states of the brain. To be in pain is for your c-fibers to be firing. The Token-Identity Theory: Every mental state token is identical to some token physical state of the brain. The Type-Identity Theory: Every mental state type is identical to some type of physical state of the brain.

Saul Kripke

The Necessity of Identity The Necessity of Identity: For any x and y, if x is identical to y, then x is necessarily identical to y. x is necessarily F iff x is F and x couldn’t have existed without being F (i.e., x is essentially F). x is contingently F iff x is F and x could have existed without being F (i.e., x is accidently F). Leibniz’s Law: For any x and y, if x is identical to y, then x and y have all of the same properties.

Kripke’s Argument 1) x is identical to y.[assume for CP] 2) y is necessarily identical to y. 3) [So] x is necessarily identical to y. 4) [So] If x is identical to y, then x is necessarily identical to y. 5) [So] For any x and y, if x is identical to y, the x is necessarily identical to y.

The Modal Argument 1) If the Identity Theory is correct, then pain is identical to the firing of C-fibers. 2) If pain is identical to the firing of C-fibers, then pain is necessarily identical to the firing of C-fibers. 3) If pain is necessarily identical to firing of C-fibers, then pain could not have existed without the firing of C- fibers. 4) Pain could have existed without the firing of C-fibers. 5) [So] The Identity Theory is not correct.

The Parody Argument 1) If current chemical theory is correct, then water is identical to H2O. 2) If water is identical to H2O, then water is necessarily identical to H2O. 3) If water is necessarily identical to H2O, then water could not have existed without H2O. 4) Water could have existed without H2O. 5) [So] Current chemical theory is not correct.

Textbook Kripkeanism Textbook Kripkeanism: The Walt Disney Principle is true. Apparent counterexamples involve the misdescription of a genuine possibility.

Textbook Kripkeanism When someone says, inaccurately, that heat might have turned out not to be molecular motion, what is true in what he says is that someone could have sensed a phenomenon in the same way we sense heat… even though that phenomenon was not molecular motion. He means, additionally, that the planet might have been inhabited by creatures who [got the sensation we got from heat]… in the presence of something else… even though it would not be molecular motion (and therefore not heat!), which was causing the sensation. (N&N, pp., )

Textbook Kripkeanism When someone says, inaccurately, that water might have turned out not to be H2O, what is true in what he says is that someone could have interacted with a substance in the same way we interact with water… even though that substance was not H2O. He means, additionally, that the planet might have been inhabited by creatures who got the sensations we get from water—the taste, the feel, etc.– in the presence of something else… even though it would not be H2O (and therefore not water!), which was causing the sensations.

The Parody Argument 1) If current chemical theory is correct, then water is identical to H2O. 2) If water is identical to H2O, then water is necessarily identical to H2O. 3) If water is necessarily identical to H2O, then water could not have existed without H2O. 4) Water could have existed without H2O. 5) [So] Current chemical theory is not correct.

The Modal Argument 1) If the Identity Theory is correct, then pain is identical to the firing of C-fibers. 2) If pain is identical to the firing of C-fibers, then pain is necessarily identical to the firing of C-fibers. 3) If pain is necessarily identical to firing of C-fibers, then pain could not have existed without the firing of C- fibers. 4) Pain could have existed without the firing of C-fibers. 5) [So] The Identity Theory is not correct.

Textbook Kripkeanism When someone says, inaccurately, that pain might have turned out not to be C-fibers firing, what is true in what he says is that someone could have sensed a phenomenon in the same way we sense pain… even though that phenomenon was not C-fibers firing. He means, additionally, that the planet might have been inhabited by creatures who [got the sensation we got from pain]… in the presence of something else… even though it would not be C-fibers firing (and therefore not pain!), which was causing the sensation.