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LIN 1080 Semantics
Lecture 13
Albert Gatt
In this lecture
 We take a look at argument structure and thematic roles
 these are the parts of the sentence that correspond to the
participants in the situation described
 thematic roles help to classify the kinds of relations between
entities (people, things, places) in a situation
Part 1
Classifying thematic roles
Some distinctions
Mary hit John.
 Syntactic functions:
 Surface subject: Mary
 Surface object: John
 Thematic roles:
 Mary is the AGENT in the situation
 John is the PATIENT
Some distinctions
John was hit by Mary.
 Syntactic functions:
 Surface subject: John
 Surface prepositional object: Mary
 Thematic roles:
 Mary is still the AGENT in the situation
 John is still the PATIENT
 Arguments with specific roles have typical syntactic
functions, but roles stay constant when the surface order
changes.
Thematic roles: AGENT
 doer or initiator of an action
 capable of “volitional” behaviour
 typically animate
Silvia cooked dinner.
The cat climbed the wall.
 Related to: ACTOR
 conceived as a more general role
 AGENT is a kind of ACTOR
 ACTOR does not need to display volition:
The car ran over the hedgehog
Thematic roles: AGENT (cont)
 Some tests have been proposed for AGENT-hood
 Jackendoff (1972):
 to test if a participant is an agent, try adding some phrase that
makes volition explicit
 John opened the letter deliberately
 John opened the letter in order to read it
 ?John received the letter in order to read it
Thematic roles: PATIENT
 undergoes the effect of some action
 often changes its state
 can be animate or inanimate
The sun melted the ice.
Thematic roles: PATIENT
 Jackendoff (1990) proposes the following test:
 if it makes sense to ask What happened to X? then X is probably the
patient.
Sue slapped John.
What happened to John? (He got slapped)
The book was in the library.
What happened to the book? (Anomalous!)
What happened to the library? (Anomalous!)
Thematic roles: THEME
 Entity which is moved by an action or whose location or state
is described
 need not be animate
The book is in the library.
 Some authors treat THEME and PATIENT as the same role.
Thematic roles: EXPERIENCER
 Used for entities that display some awareness of an action/
sensation/state
 not volitional, unlike AGENT
I feel sick.
Jack saw the lion in the bushes.
Thematic roles: BENEFICIARY
 entity for whose benefit the action was performed
 typically realised as complement of a for-PP
Jackson painted a picture for his wife
Thematic roles: INSTRUMENT
 the means by which an action is performed
 often realised as complement of a with-PP
He burst the door with a sledgehammer
Thematic roles: LOCATION
 place where something is
 place where action takes place
 typically realised as complement of a locative PP (under, in,
on)
The tiger hid behind the curtain
Thematic roles: GOAL
 thing towards which something moves
 can be literal or metaphorical movement
John gave the letter to Mary
She told the Joke to her friends
 NB: some theorists refer to certain GOALs as RECIPIENTs
 especially in the case of give and similar verbs
Thematic roles: SOURCE
 the entity from which something moves or originates
 can be literal or metaphorical
 typically realised in a from-PP
I got the idea from Jason.
I come from Malta.
Problems with these classifications
 Different authors have different views about what qualifies as
what
 e.g. to some, there is no distinction between PATIENT and
THEME
 There are some ambiguous cases:
Margarita received a gift.
 GOAL? RECIPIENT? BENEFICIARY?
Dealing with the ambiguity
 Jackendoff (1990):
 some roles are more primary than others
 different roles belong to different levels of interpretation
 thematic tier: describes spatial relations
roles include THEME, GOAL, SOURCE, LOCATION
 action tier: describes ACTOR-PATIENT type relations
 main roles are therefore ACTOR/AGENT and PATIENT,
EXPERIENCER, BENEFICIARY, INSTRUMENT

 Sentences receive an interpretation on both levels
Jackendoff (1990)
 Sue hit Fred.
 thematic tier: THEME (Sue) GOAL (Fred)
 action tier: ACTOR (Sue) PATIENT (Fred)
 Bill entered the room.
 thematic tier: THEME (Bill) GOAL (the room)
 action tier: ACTOR (Bill)
 N.B. not all arguments need to be represented at both
levels!
Difficulties with thematic roles
 Intuitively, they are there, but they are very difficult to
delimit
 Classifications like AGENT/PATIENT etc must allow for a lot of
variation in what qualifies.
 e.g. the child cracked the mirror
 is the mirror a PATIENT?
 More serious problem: how to define each role.
 there needs to be some semantic motivation
 i.e. we need to show that the distinctions capture meaningful
distinctions in a semantic theory
Dowty (1991)
 Attempt to deal with the problem of defining thematic roles
correctly.
 Example: What does x have in common in:
 x murders y,
 x nominates y
 x interrogates y
 Dowty:
 they have a set of entailments in common
 x does a volitional act
 x causes an event to take place involving y
 x moves or changes externally
 NB. These entailments are carried by all the above sentences,
and they all feature the role of x
Dowty (1991)
 Proposed to view roles as prototypes
 rather than define several roles, each crisply delimited, he
proposed two basic prototypes: Proto-Agent, Proto-Patient
 each prototype has a list of characteristic entailments
 arguments in a sentence qualify as one or the other to different
degrees
Dowty (1991)

1.
2.
3.
4.
Proto-Agent
volitional involvement in the
event or state
sentience / perception
causes an event or a change of
state in another participant
movement relative to the
position of another participant
 Proto-Patient
1. undergoes a change of state
2. incremental theme
3. causally affected by another
participant
4. stationary relative to movement
of another participant
Degrees of thematic role-hood
 Under Dowty’s conception, some arguments will be more
Proto-Agent-like than Proto-Patient-like
 John cleaned the house
 has all the entailments of the Proto-Agent
 John dropped the suitcase
 lacks volition, but has sentience
 The storm destroyed the house
 lacks sentience and volition
Part 2
Why thematic roles?
Thematic roles and argument selection
 There seem to be systematic ways in which roles typically map to
grammatical functions
 e.g. EXPERIENCER is usually the subject
 PATIENT is usually the object
 Roles therefore allow us to predict how arguments are linked to the verb
given its semantics.
 Often, a theta-grid for a verb is proposed
 Crack: <AGENT, PATIENT, INSTRUMENT>
 underlined role maps to subject
 order of roles allows prediction of grammatical function
Dowty’s Argument Selection Principle
 if a verb takes a subject and an object
 the argument with the greatest number of Proto-Agent properties will be
the one selected as subject;
 the one with the greatest no. of Proto-Patient properties will be selected
as object.
Dowty on argument selection
 Corollary 1 of the ASP:
 if two arguments have roughly equal numbers of Proto-Agent
and Proto-Patient properties, either one or both may be the
direct object
 Corollary 2 of the ASP:
 with a 3-place predicate (e.g. give), the direct object will
probably be the argument with the greatest number of ProtoPatient properties
The rationale
 Dowty’s model seems to have high predictive power.
 e.g. In describing a shoot event, involving <John, the dog, the
gun>, we are likely to map John to subject, the dog to object,
the gun to a PP
 John has the highest no. of Proto-Agent roles
 out of the dog and the gun, dog has higher no. of Proto-Patient
roles
Other thematic roles
 Proto-Agent and Proto-Patient are the basic prototypes in
Dowty’s model
 the idea is to then view other roles like EXPERIENCER etc
as sharing some of the properties of a Proto-Agent/Patient,
but not all
Dowty’s thematic role hierarchy
 Dowty’s principles are meant as (violable) constraints on how
arguments of a verb are linked to it syntactically.
 They also allow us to speak of candidacy for subjecthood by
“degrees”
 Proposed hierarchy:
AGENT >
INSTRUMENT
EXPERIENCER
> PATIENT >
SOURCE
GOAL
 elements higher up have more Proto-Agent properties, so more likely
to be subjects
Summary
 Thematic roles are a crucial linking feature between syntax
and semantics
 In models like Dowty’s, some attempts are made to predict
syntactic features (subject, object etc) from underlying
semantics