Philosophy and Cognitive SciencePhilosophy and Cognitive Science

Conceptual Role Conceptual Role SemanticsSemantics

Joe LauJoe Lau

PhilosophyPhilosophy

HKUHKU

ReadingsReadings

Robert CumminsRobert Cummins Excerpts on reserve at main office.Excerpts on reserve at main office.

Ned BlockNed Block Online article.Online article. ““Advertisement for a theory of Advertisement for a theory of

semantics”, on reserve.semantics”, on reserve.

TopicTopic

Some closely related theoriesSome closely related theories Conceptual role semantics (CRS)Conceptual role semantics (CRS) Computational role semanticsComputational role semantics Functional role semanticsFunctional role semantics Procedural semanticsProcedural semantics

Three questions about Three questions about a representational a representational systemsystem Which are the Which are the

representations?representations? What do the representations What do the representations

mean?mean? What makes a representation What makes a representation

mean what it does? mean what it does?

Q1 : Identifying Q1 : Identifying representationsrepresentations

Which Which physical propertiesphysical properties / / statesstates / / objectsobjects are used to are used to encode information / carry encode information / carry meaning?meaning?

Which are the symbols?Which are the symbols? Information encoded by single Information encoded by single

neuron in the brain, or groups of neuron in the brain, or groups of neurons? In what form?neurons? In what form?

Structured? Pictorial? Linguistic?Structured? Pictorial? Linguistic?

Q2 : What do they Q2 : What do they mean?mean?

Identifying their content / what Identifying their content / what the symbols represent.the symbols represent. ““insalata” means insalata” means saladsalad in Spanish. in Spanish. The firing of this neuron represents The firing of this neuron represents

the boundary of a surface.the boundary of a surface.

Q3 : theory of Q3 : theory of meaningmeaning

Questions that remains even Questions that remains even after the meaning of a after the meaning of a representation is known.representation is known. Given that X means Y, what Given that X means Y, what

explains the fact that X means Y?explains the fact that X means Y? What is it for something to have a What is it for something to have a

particular meaning?particular meaning?

Comparing Q2 and Comparing Q2 and Q3Q3

Q2Q2 Specifically about Specifically about

a system of a system of representation.representation.

An empirical An empirical question to be question to be resolved by resolved by empirical empirical investigations.investigations.

Q3Q3 A general question A general question

about the nature about the nature of meaning.of meaning.

A philosophical A philosophical question about question about how the concept how the concept of representation of representation is to be is to be understood.understood.

CRSCRS

A theory of meaning that A theory of meaning that proposes an answer to the third proposes an answer to the third question.question.

Better : a very rough and Better : a very rough and incomplete framework for incomplete framework for answering the third question.answering the third question.

Intrinsic vs. Intrinsic vs. relational propertiesrelational properties An An intrinsicintrinsic property of X : a property of X : a

property that depends only on property that depends only on those properties internal to X.those properties internal to X. Example : the mass of an objectExample : the mass of an object

A A relationalrelational property of X : a property of X : a property of X that depends on property of X that depends on objects that exist externally of objects that exist externally of X.X. Example : being a fatherExample : being a father

Meaning as a Meaning as a relational propertyrelational property

Being meaningful, having a Being meaningful, having a particular meaning are relational particular meaning are relational properties of representations.properties of representations. The intrinsic properties of a The intrinsic properties of a

physical object is not enough to physical object is not enough to determine its meaning.determine its meaning.

The meaning of a representation The meaning of a representation can change without changing its can change without changing its intrinsic properties.intrinsic properties.

A unitary theory?A unitary theory?

Is there one single theory of Is there one single theory of meaning that applies to :meaning that applies to : meaningful expressions in natural meaningful expressions in natural

languageslanguages meaningful mental representationsmeaningful mental representations

Meaning as Meaning as covariationcovariation

The meaning of a mental The meaning of a mental representation X depends on representation X depends on what X covaries with.what X covaries with. X covaries with Y = X causally X covaries with Y = X causally

correlates with Y correlates with Y

ExampleExample

Hubel and Wiesel : orientation Hubel and Wiesel : orientation selectivity in the primary visual selectivity in the primary visual cortex (area V1)cortex (area V1)

Activity of cells represent the Activity of cells represent the presence of bars or boundaries presence of bars or boundaries at a certain orientation.at a certain orientation.

CriticismCriticism

At best : works for “detector” At best : works for “detector” representations that indicate representations that indicate proximate stimulus.proximate stimulus. Still : such representations might Still : such representations might

covary with lots of things.covary with lots of things. But not the higher cognitive But not the higher cognitive

representations.representations. Inaccurate covariationInaccurate covariation Non-existent covariationNon-existent covariation

Functional role Functional role semanticssemantics

Functionalism : Mental states are Functionalism : Mental states are defined by their functional role.defined by their functional role. Role vs. occupantRole vs. occupant Intentional mental states are Intentional mental states are

defined by (a) type (e.g. belief) and defined by (a) type (e.g. belief) and (b) content (e.g. that snow is white)(b) content (e.g. that snow is white)

So the content of intentional mental So the content of intentional mental states are defined and explained by states are defined and explained by their functional role.their functional role.

Functional role = ???Functional role = ???

A relational property; role within A relational property; role within the functional organization of the the functional organization of the mindmind

Conceptual role semantics Conceptual role semantics (CRS) (CRS) Content defined by the role of a Content defined by the role of a

representation in cognition, e.g. representation in cognition, e.g. reasoning, decision, perception, reasoning, decision, perception, memory. memory.

ExampleExample

Consider these inferential transitions Consider these inferential transitions between the beliefs of an agent :between the beliefs of an agent : P*QP*Q P P P*QP*Q Q Q P, Q P, Q P*Q P*Q

Interpretation : “*” represents Interpretation : “*” represents conjunction (“and”).conjunction (“and”). Meaning determined by role in reasoning.Meaning determined by role in reasoning.

Advantages of CRSAdvantages of CRS

Explain differences in meaning Explain differences in meaning despite sameness of reference.despite sameness of reference. Lee : “I have a lot of money.”Lee : “I have a lot of money.” Lee : “Lee has a lot of money.”Lee : “Lee has a lot of money.”

Computational-RSComputational-RS

CompRS = CRS + CompRS = CRS + ComputationalismComputationalism

Computionalism : cognition is Computionalism : cognition is explained by computations.explained by computations.

Mental content defined by Mental content defined by

conceptual role conceptual role Mental content Mental content defined by computational role (role defined by computational role (role of representation in the mind’s of representation in the mind’s program)program)

CRS and FRSCRS and FRS

CRS is one version of FRSCRS is one version of FRS CRS is true CRS is true FRS is trueFRS is true

FRS is true not FRS is true not FRS is trueFRS is true There might be aspects of There might be aspects of

functional role which are not functional role which are not computational.computational.

e.g. role in interacting with some non-e.g. role in interacting with some non-computational system.computational system.

CRS and covariationCRS and covariation

Internal conceptual role might Internal conceptual role might not determine all aspects of not determine all aspects of meaning.meaning.

External causal connections have External causal connections have a role in determining which a role in determining which particular object a representation particular object a representation is about.is about.

Tung-1 Tung-2

Two factor CRSTwo factor CRS Which is more important? Internal or Which is more important? Internal or

external factorexternal factor Is this plausible?Is this plausible?

Internal factor imposes constraints on Internal factor imposes constraints on what the representation can be aboutwhat the representation can be about

External factor determines which External factor determines which particular object or property is particular object or property is represented.represented.

But perhaps some content is determined But perhaps some content is determined entirely by the internal factor (e.g. “and”).entirely by the internal factor (e.g. “and”).

Narrow vs. wide Narrow vs. wide contentcontent

Narrow content : content that depends only on what is inside the head.

Wide content : content that depends also on objects outside the head.