Theta Theory addresses the specific semantic relationships within a sentence. These relationships are held between a verb, and the noun phrases, or arguments associated with the verb. The verb assigns a theta role to each of its arguments within the sentence. This theory shows that every verb and its chosen arguments share specific semantic properties.
The selection of arguments is based on the semantic properties of the verb and the noun phrase. These roles are predetermined by verb assignment in the deep structure of a phrase, and are not changed by transformations. Once a theta role is assigned, the role remains as such.
It is stated that every noun phrase argument of a verb MUST be assign a theta role. Similarly, only one theta role can be assigned to an argument. Meaning that you cannot have the same theta role for 2 arguments of the same verb.
- Agent: an entity that performs an intentional action of some kind
- John ate the apple.
- John intentionally bit into and consumed the apple.
- Experiencer: an entity that undergoes a perception, emotion, or a change in circumstance
- The cat felt sick.
- The cat is happy when he sees catnip.He undergoes an emotion, and experiences the characteristics of ‘happy’.
- Theme: entity immediately affected or changed by an action. Can also be a description in a copula structure.
- Jane finally cashed her paycheck.
- The paycheck is what is being affected by the verb, it is being cashed.
- Instrument: an entity used to perform an action
- John hit the baseball with the bat.
- The bat is what John uses to carry out the action of the verb.
- Benefactive: an entity which receives or benefits from the action of the verb
- Jeff bought his girlfriend
- His girlfriend is benefiting from this action, she is receiving the flowers from Jeff.
- Goal: an entity or direction towards which the action of the verb moves or is directed.
- Mary skipping to the cafeteria.
- The cafeteria is where Mary is skipping towards.
- Source: an entity from which the action of the verb moves.
- Bethany ran from my room to her room in no time.
- ‘my room’ is where she is moving form. The verb is moving from ‘my room’ to her room.
- Location: the place in which the action of the verb takes place
- I sunbathed on the beach.
- The beach is where I am carrying out the action of the verb, sunbathing.
- Temporal: the time at which the action of the verb occurs
- I finish my homework every week so I can relax when I don’t have classes.
- Every week is the recurring time that the action of the verb is being carried out.
Theta grids express the arguments of which are the minimum requirement by a verb. A theta grid is written next to the verb, and is enclosed in <>. Examine the following examples.
Buy <agent, theme>
As a transitive verb, buy requires some to do the action of buying (agent) as well as something that is being bought (theme). More theta roles could be added, such as Location or Benefactive, but only those arguments that are required are put in a theta grid.
Offer <agent, theme, benefactive>
Another transitive verb, offer, requires more than the previous example. This verb requires someone to carry out the act of offering (agent), something to be offered (theme), and an entity for the theme to be offered to (benefactive).
An intransitive verb, sleep, does not require much therefore the theta grid only consists of one role. Since the person sleeping cannot physically put themselves into a sleep state, the action of sleeping overcomes the them making them the experiencer.
Donavon Thomas (2016)