Grammatical functions (or grammatical relations) refer to syntactic relationships between participants in a proposition. Examples are subject, object, adjunct, complement. It is a role of a noun phrase or complement clause that determines syntactic behaviors such as the following:
1. Word position in a clause
2. Verb agreement
3. Participation and behavior in such operations as passivization
Before we discuss about grammatical relation that is morphosyntactic, let’s see semantic roles or thematic roles that are conceptual notions. Though, semantic roles do not correspond directly to grammatical relations, but they do show the arguments of the predicates that grammatical-relation constituents determined their syntactic behaviors for. Notice what varying semantic roles a grammatical subject can play:
Sentence Grammatical relation Semantic role
Bob opened the door with a key. Bob = SUBJECT Bob = AGENT
The key opened the door. The key = SUBJECT The key = INSTRUMENT
The door opened. The door = SUBJECT The door = PATIENT
The mapping between the grammatical relation of subject or object and the thematic role of agent or patient are clearly demonstrated by the existence of the English passive voice. Let’s analyze an example of a passive sentence:
This door was opened by Bob.
In this passive sentence, door is the grammatical subject or the semantic role of patient, and Bob is an oblique object. However, Bob has the semantic role of agent. Some theories of linguistics would call Bob the ‘logical subject’.
There are nine kinds of semantic roles that indentify arguments of the predicates:
Agents are arguments that bring about a state of affairs. The line between agents, on the one hand, and instruments or causes, on the other, can be fuzzy, but agents are (or are perceived to be) conscious or sentient, in a way that instruments or causes aren't.
1. Agent → My mother wrote me a letter.
2. Instrument → This key opens the door to the main office.
3. Cause → Hurricane-force winds demolished much of the town.
Experiencers are arguments that undergo a sensory, cognitive, or emotional experience.
4. Many people fear snakes.
Recipients are arguments that receive something (whether good or bad) in a situation.
5. They gave the workers a raise.
Recipients can be the endpoints of paths.
6. I'd like to send this package to my sister.
Locations are simply places; like recipients, they can serve as endpoints of paths.
7. We put the book on the shelf.
Measure or amount arguments express extension along some dimension (length, duration, cost, and so on).
8. The book costs ten dollars.
Theme refers to an argument undergoing motion of some sort, including motion in a metaphorical sense, such as a change of state.
9. This key opens the door to the main office.
Now, let’s take a look at the grammatical relation that can be defined as subject, first object and second object with all semantic roles they can perform:
1. Subjects are ordinarily the only argument to precede the predicate in English.
a. Agent: The lions devoured the wildebeest.
b. Instrument: This key opens the door to the main office.
c. Cause: Hurricane-force winds demolished much of the town.
d. Experiencer: The rhesus monkey had never seen snow before.
e. Recipient: The workers were given a raise.
f. Goal: The summit wasn't attained until years later.
g. Path: An unpaved road led up to the shanty.
h. Theme: The wildebeest was devoured by the lions.
2. First objects are the noun phrase argument that typically follows a transitive verb. Again, a wide variety of thematic roles can be expressed as first objects.
a. Instrument: You should use this key for the door to the main office.
b. Experiencer: The children's drawings pleased their parents no end.
c. Recipient: They gave the workers a raise.
d. Goal: We reached our hotel after a subway ride of less than ten minutes.
e. Path: We drove the scenic route.
f. Measure: The performance lasted two hours.
g. Theme: The lions devoured the wildebeest.
3. Second objects only occur with ditransitive verbs. Unlike the other grammatical relations, second objects are thematically very restricted---namely, to themes.
Theme: They gave the workers a raise.
Finally, it should be noted that most thematic roles are not restricted to being expressed as bare noun phrases, but can also be expressed as prepositional phrases.
a. Agent: The wildebeest was devoured by the lions.
b. Instrument: The door to the main office can be unlocked with this key.
c. Cause: Much of the town was demolished by hurricane-force winds.
d. Experiencer: Snakes are feared by many people.
e. Goal: I'd like to send this package to France.
f. Path: Lucky raced across the lawn to the edge of the forest.