Intermediate Syntax
Theta Roles
Linguistics 322
Intermediate Syntax
Theta roles are the names of the participant roles associated
with a predicate: the predicate may be a verb, an adjective, a preposition,
or a noun. The participant is usually said to be an argument of the predicate.
In the following sentence, John is the argument of die. John is a participant; he is the one who dies. If one
undergoes an experience denoted by the verb, the theta-role is called an
experiencer:
(1) John died.
Here, John has experienced death. WE may represent this argument in propositional form:
(2) [TENSE [+Past] < DIE <theme: JOHN>>].
If an object is in motion or in a steady state as the speakers
perceives the state, or it it is the topic of discussion, it is called a
theme:
(3) The book is blue.
(4) The ball rolled away.
(5) Did you see Molly?
In (3) the book is the theme, in (4) the ball is the theme, and in (5), Molly is the theme. In the latter case Molly is the topic of conversation; you is an experiencer. The theme does not imply a information processing unit (IPU)--see next two sections.
(6) [TENSE [-Past] < BLUE <theme: BOOK> >].
(7) [TENSE [+Past] < ROLL <theme: BALL> <AWAY> >].
(8) [TENSE [+Past] < SEE <theme: MOLLY> <experiencer: YOU> >].
If the participant is causing something to happen or
is in some way responsible for something happening or has conscious control
over something happening, the participant is called an agent:
(9) Bill is building a house.
(10) Mary bought a beat up car.
(11) The dog is running away.
The subject in each of these sentences is an agent. The progressive aspect is not represented in the following grammatical propositional forms:
(12) [TENSE [+Past] < BUILD <goal: HOUSE> <agent: BILL> >].
(13) [TENSE [+Past] < BUY <theme: CAR> <agent: MARY> >].
(14) [TENSE [+Past] < RUN <theme: DOG> <agent: DOG> <AWAY> >].
We claim here that an agent deals with the submission of information. The agent sends out information to a certain form that is responsible for causing an event to occur. The immediate source of this information we will call an Information Processing Unit (IPU). We will look at three different scenarios.
In the first one image a circular wormhole. In this wormhole there is one worm that constantly moves through this wormhole. The worm constantly sends out information to that part of his body that accounts for his movement. The worm keeps moving never stopping or doing anything else. This is as simple a situation as can be imagined which involves information transmission. Note that we are overlooking the death/alive factor. In the simplest scenario, this is not a factor. Here, the worm is an agent. It is sending out information by means of its IPU. The entire worm is a theme as it is moving with no observable internal change.
In the second scenario, suppose a human is crawling through the wormhole instead of a worm. All we are interested in here is the fact that the human sends a message by means of its IPU to certain muscles that induce the motion which English speakers refer to as 'crawl.' Only one message is sent out. Note that the IPU of humans and all higher organisms is called a brain. There is no formal difference between these first two scenarios--the only difference is in what we perceive of as a worm or as a human.
In the third scenario, suppose that a a minicomputer is in the wormhole. It is sending out only one bit of information repeatedly by means of its IPU to a some part of it that causes the minicomputer to move through the wormhole. The IPU of a computer is not called a brain. In the definition of agent adopted here, the computer is an agent. (We ignore here the interesting and often discussed issue of what differentiates a human, from a worm, from a computer.)
Nevertheless, the three scenarios are the same. Each movable form has an IPU that sends out one b it of information to some form that is the direct cause of movement. The IPU is the agent. In normal language, we refer to the entire body containing the IPU as the agent:
As long as the human brain functions and sends information to the hands and feet, we say that the human is the agent as in (15). The human body is the theme of the motion, not the brain. Note that in (4) the subject is not an agent. The subject we discuss in the following section.
Now, let us change the above three-part scenario to
the following. The wormhole is not circular but is straight and has two
ends. The worm still moves through the wormhole. But when it reaches the
end, it can no longer move. Suppose that contact with the end wall of the
wormhole sends a message to the IPU of the worm. And suppose that the worm
is now able to send one of two message to its body. Move and Reverse Movement.
When the worm receives the information that it has reached the end (usually
through the sense of touch), it send the message to its body to reverse
the direction. When the worm reaches the other end, it receives the same
message it sends another message to reverse direction and it then continues
to the send the message Move.
We call the IPU an experiencer when it receives information and an agent when it submits information. The body is still a theme. Thus, we now have two events: Move and agent, Reverse Movement, agent, and experiencer. The term predicate is used to refer to Move and and Reverse Movement, and the term argument is used to refer to agent, theme, and experiencer as a property of the predicate.
The experiencer is distinct from the agent. It is possible for the IPU to receive information and not respond to it. For example, consider:
(16) is ambiguous. In the intended reading John is experiencing being cold. John is the experiencer. Something is sending him the information that he is experiencing this condition. But in (18) John is doing nothing about it. John is an experiencer only in (17). In the second reading, John feels cold to the touch. That is someone else is experiencing John's coldness. John's body is cold. We do not know if John is experiencing being cold or not. John could be dead, in which case his IPU (brain) is not function and it is neither receiving messages or submitting messages:
(17) [TENSE [+Past] < DIE <experiencer: JOHN> <state <COLD> >].
(18) [TENSE [+Past] < DIE <theme: JOHN> <state <COLD> >].
Normally, we perceive of animals and humans as experiencers but not computers. The computer is an experiencer in the following situation. When the minicomputer reaches the end bumping into it, a message is sent to the IPU of the computer that the end has been reached. The computer then sends out a message to some mechanism (an instrument) that reverses the direction of it. Then the computer sends out the message 'Move.'
In (5) above seeing is an experiential event. The seer is receiving information: the object seen. The object seen is the theme. The seer is not sending out information--he is not an agent.
The theta role possessor refers to an object that
one has, owns, possesses, or belongs to someone:
(19) John has a book.
Book must be a theme. It sends out no messages and it receives no messages, and it does not undergo a change of state (see patient below):
(20) [TENSE [-Past] < HAVE <possessor: JOHN> <theme: <BOOK> >].
Another common theta role is the patient. The patient
is something or somebody that undergoes a change specifically implied by
the verb. Note that John in (1) is a
also a patient in that he underwent a change in state. Other patients include:
(19) Mary burned the scallops.
(20) Kelly painted the fence.
In (19) the scallops is the patient, since it underwent a change; in (20) the fence is a patient since it underwent a change (in colour). A patient occurs in the following slot:
In the above wormhole scenario there is no patient. There does not undergo an observable internal change. Suppose that the worm has a mouth and can eat a bit of the end of the wormhole and then reverses his direction. As a result of eating a bit of the end of the wormhole, the worm grows a millimeter. The worms is a patient in the sentence:
Of course, the worm is an agent in
And the wormhole end is also a patient. Note that the verb eat does not refer directly to an experience. The experience is inferred. When the worm reaches the end of the wormhole, it receives the information that it has reached the end, and then the worm sends out information to the proper organ to eat a bit of the end.
Let us suppose that this particular species of worm has
teeth. When the worm reaches the end of the wormhole, it receives that message,
and then it sends a message to the tooth muscles (or whatever) to bite into
the end, tear off a a bit of the end, and then consume it. The teeth and
associated organs are an instrument (perceptually, we humans often see the
teeth as the instrument, passing over the muscles involved):
The instrument has no IPU. It receives a message, but it cannot process it. If the message comes in, the teeth must sink into the end of the wormhole. In this way we distinguish between agent and instrument. In a sentence such as:
it is assumed that the wind has no IPU. If true, then the wind is an instrument, not an agent. It has been noted in the literature that the following sentence is ambiguous:
In one reading Bill is the agent. In the other (uncommon) reading, Bill's body is an instrument in that somehow it went through the window, but Bill had nothing to do with it. Bill did not send out a message to some part of his body to propel his body through the window. Or, Bill broke the window when he fell through it.
John is an instrument here unless he intentionally fell through the window with the intent of breaking it. The instrument occurs as the direct object of the verb use:
Other theta roles include goal, source, and path.
The first three occur with events denoting specific motion:
Let us illustrate with the worm. In the simplest scenario, the worm is the agent. No reference had been made to the wormhole. In the following sentence:
The wormhole refers to the path of the movement of the worm. The wormhole bears the theta role path. Since the wormhole is circular, there is no source or goal. The worm just keeps moving. In the second case, there are two ends of the wormhole. The worm moves from one end to the other. Thus, one end is the source, and the other is the goal. Note that without tense, it would be impossible to determine which end is the goal and which is the source. Bring in the factor of tense, the source is the end in the past tense, and the goal is the end in the future:
Another theta role is reason. The English words because
and since mark reason:
Now, let us look at the wormhole scenario. In the simplest case, the worm moves through the wormhole without end. There is no cause and effect. That it moves seems to be the case without cause and effect. It is not evident to the casual observer that the worm may be programmed to do so. It is like the universe: it is because it is.
Next let us look at the second scenario. The worm bumps into the end. A message is sent to its IPU. Then the worm send out the message Reverse Movement. There is a cause and effect relation ship here. The first message is the cause of the second message--the effect.
Theta roles play an important role in NP raising and Case
theory (topics for L322). The above is a sketch of theta roles. Theta roles
are closely tied to the meaning of the predicate that assigns the theta
role of each argument.
Go to raising.
Go to case.theory
Go to tense.aspect.
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