Mind-Brain Theory Peter Carruthers, Slides of Philosophy of mind

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“The Mind is the Brain”

Peter Carruthers

Mental States vs. Brain States

“Mental States?”

• This term sometimes confuses some students.
• A “mental state” is just a “state” or condition some “mind” might be in, like “seeing,” or “thinking,” “being in pain,” etc. - So, thoughts, pains, desires, beliefs, etc., are all “mental states.”
• We will use this term in a “neutral” way, that is, without presupposing either dualism or materialism. - We need to have some way of talking about these things that doesn’t “takes sides” in the dispute.

The Options

• According to the dualist, mental states are

states of an immaterial mind or soul.

• There are different varieties of materialism:
  • According to the Identity Theory (which Carruthers supports) mental states are identical to brain states.
  • According to eliminative materialism (which we are not reading), there are no such things as mental states.

Mind/Body (or “ Substance ”) Dualism

• Descartes held that mind and body were

fundamentally different.

• Minds are thinking, but non-spatial
• Bodies are spatial, but non-thinking.
• This is known as Substance (or Metaphysical )

Dualism.

• That is, the universe is composed of two, fundamental, and ultimately distinct, kinds of “stuff,” i.e., two distinct (kinds of) “ Substance .”

Dualism vs. Monism

• The alternative to Substance Dualism is

Substance Monism.

• No one seems to hold that there more than two ultimate kinds of stuff.
• Substance Monism claims there is only one

fundamental kind of substance.

• This implies that everything is ultimately “composed of” and/or explained in terms of a single basic kind of “stuff.”

Two Varieties of Materialism:

The Identity Theory:

• Mental states (thoughts, sensations, etc.), are identical to states of the brain and/or central nervous system: - In the way in which water is identical to H 2 O, or lightning is identical to discharges of electricity in the atmosphere. Eliminative Materialism: - There really are no such things as “mental states” (“thoughts,” “sensations,” etc.): - Like ghosts or “caloric,” we used to believe in them. We haven’t learned what they “really” are (what they are “identical to”): rather, we have learned that they really aren’t , i.e., that there are no such things.

Dualism vs. Materialism

Dualism

• Dualism claims that there is a mental substance, a mind or soul.
• For the dualist, “thoughts,” “feelings,” and other “mental states” are states of this mental substance. Materialism
• Materialism claims that there is no mental substance.
• For the Identity Theory (a version of materialism), what we call “mental states” are real, but what they really are (what they are identical to) are brain states, and/or events in the central nervous system.
• For Eliminative Materialism (another version of materialism), there simply are no such things as mental states. They don’t exist, and so there is nothing they are identical to.

The Identity Theory

• The Identity Theory rejects Dualism, and is a

form of Materialism.

• It claims that everything that exists is,

ultimately, material.

• The identity theory accepts that mental states

are, in some sense, “real.”

• But it claims that what they really are are

states of brain and/or central nervous system.

A Problem for Dualism

Problem: How could mind causally interact with matter?

Mind/Body Causal Interaction?

An Argument For Identity

Strategy

• Carruthers turns a criticism of mind/body dualism into an argument for the identity theory.
• Dualism says that my choosing to move my arm is something that happens in my non-material mind. - The problem is explaining how this “mental event” can cause a physical event—the movement of my arm. - This is a problem because it seems that physical events can only be caused by other physical events.
• So, Carruthers concludes, if my arm moving is actually caused by my choosing (a “mental event”), then, since only a physical event can cause a phyiscal event, my choosing to move my arm must be (identical to) a physical event.

The Argument

• 1. At least some mental events (like

choosing to do something) cause physical

events.

• 2. But only physical events can cause

physical events.

• 3. So, at least some mental events must be

physical events.

• i.e., at least some mental states are identical to brain states.