Introduction to Cognitive Science Philosophy Nov 2005 :: Lecture #1 :: Joe Lau :: Philosophy HKU.

Introduction to Cognitive Science

Philosophy

Nov 2005 :: Lecture #1 :: Joe Lau :: Philosophy HKU

Topics for today The role of philosophy in cognitive science A brief history of cognitive science Philosophical theories of the mind

Next week The computer model of the mind Challenges to the computer model

Why philosophy?

Methodology of philosophy - reasoning Logic and conceptual analysis Not experimentation.

Cognitive Science is a science. So why is philosophy relevant to cognitive science?

The relevance of philosophy Systematic description

Making things clear, systematic, and logical. Explain the basic concepts and assumptions.

Explaining representation, consciousness, etc. Describe the big picture.

What is cognitive science? Critical reflection

Evaluate experiments and arguments. Constructive speculation

Propose theories and concepts.

Cognitive science again Cognitive science = Science of the mind Features

Different areas – perception, language, … Different levels – task, representation and

algorithm, hardware implementation Inter-disciplinary Computational explanations of information

processing

Before cognitive science Philosophers

Plato, Aristotle, Descartes, Hume, Kant, …

The beginning of psychology Wilhelm Wundt (1832-1920)

First psychology laboratory William James (1842-1910)

The Principles of Psychology

Emergence of cognitive science (1950s)

Reaction to behaviorism in psychology Pavlov, Skinner, Thorndike, Watson, etc.

What is behaviorism? Scientific psychology should

focus only on observable behavior.

Behavior to be explained in terms of conditioning.

The ongoing “cognitive revolution”

Rejection of behaviorism in psychology Psychological explanations must take into account internal m

ental states that are not directly observable. George Miller (1956) “The Magical Number Seven, Plus or Min

us Two” Chomsky (1957) Syntactic Structures Chomsky (1959) “A Review of B. F. Skinner's Verbal Behavior”

The start of modern computing and AI Mathematical definition of computation (Turing, Church, …) Electronic computers - The beginning of AI

John McCarthy, Marvin Minsky, Allen Newell, Herbert Simon

Developments in neurophysiology Brain functions and information processing in neurons

Penfield, Hubel and Wiesel, Sperry, Melzack and Wall

Necessity of interdisciplinary research

Philosophy Emotions and moods Emotions and rationality

Psychology How emotions affect decisions

Linguistics Emotional words in different cultures

Neurophysiology Emotions and hormones The effect of brain damage

http://www.hku.hk/fmri/

Topics for today The role of philosophy in cognitive science A brief history of cognitive science Philosophical theories of the mind

What is the mind? Mind = the subject of mental states. What are mental states?

Intentional mental states Examples: beliefs and desires Mental states with content.

Emotions Anger, jealousy, …

Bodily sensations Pains, itches, …

Perceptions Seeing a tree, hearing a sound, …

Commonality Either intentional or conscious.

Substance dualism The mind = a spiritual substance.

Only a soul can have mental states. Animals are unconscious machines. Motivation: immortality & religious beliefs.

Three problems with dualism Evidential problem

Any evidence for the existence of the soul? Causal interaction problem

Mental states cause and are caused by physical states. How does the soul interact with the brain?

Explanatory problem The soul does not help us explain the nature of the mind.

Materialism / Physicalism The mind is a physical system.

Mental states are physical states. Pain = activation of area X of the brain.

Two versions of physicalism Token physicalism

Every mental state token is a physical state token. Type physicalism

Every mental state type is a physical state type.

How many letters are there in the box?

A A A A A

Type vs. Token physicalism Token physicalism

Joe’s belief that 1+1=2 at noon = activity of area A of Joe’s brain at noon.

Peter’s belief that 1+1=2 at 3pm= activity of area B of Peter’s brain at 3pm.

Type physicalism The belief that 1+1=2 = activity of brain area X.

Type physicalism and multiple-realization Is the identity statement true of every creature wit

h that belief?

Functionalism Mental state types are defined by functional

role. A mental state token of type T is the

physical state that is the occupant of role T. Role and occupant

The winning ticket = (Roughly) A ticket whose owner is entitled to obtain a prize in some competition, draw, or game.

Pain in humans can be physically different from pain in other animals belief even though they play the same role.

Defined by typical causes and effects.

Functionalism applied to pain X has pain = X is in a state that is typically

caused by bodily injury or disturbances, which causes avoidance behavior and the belief that one is in pain, and the desire to eliminate the pain.

The computer model of the mind How is it related to functionalism?

The computer model of the mind

Weak version - Computations are necessary for explaining mental processes. The mind has a computational level of

description.

Strong version - Computations are necessary and sufficient for explaining mental processes. Implication - The right kind of computation will be

sufficient for the existence of a mind.

A cruise missile Computations necessary

For self-guided navigation.

Computations sufficient?

Functionalism about the mind

Strong version of the computer model Computations are necessary and sufficient

for having a mind. Mental state types are defined by their role

in a program / functional organization. Program

For F = 1 to 10 Print F Next F

Implications of functionalism

Computational copying is sufficient for mental duplication. If X is computationally the same as Y, and X has

a mind, then Y also has a mind.

Material implementation is not directly relevant for having a mind. It does not matter what Y is made of, as long as

the computations can be implemented in the hardware.

Chinese Nation exampleNed Block (1978) “Troubles with

Functionalism”