Thematic role

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Thematic role is the semantic relationship between a predicate (e.g. a verb) and an argument (e.g. the noun phrases) of a sentence. Thematic roles include:

Agent: deliberately performs the action (e.g. Bill ate his soup quietly)
Experiencer: receives sensory or emotional input (e.g. The smell of lilies filled Jennifer's nostrils).
Theme/Patient: undergoes the action (e.g. The falling rocks crushed the car).
Instrument: used to carry out the action (e.g. Jamie cut the ribbon with a pair of scissors).
Cause: mindlessly performs the action (e.g. An avalanche destroyed the ancient temple).
Location: where the action occurs (e.g. Johnny and Linda played carelessly in the park).
Goal: what the action is directed towards (e.g. The caravan continued on toward the distant oasis).
Source: where the action originated (e.g. The rocket was launched from Central Command).

Features

Thematic roles are the same in sentences that are paraphrases.
Thematic roles may remain the same in sentences that are not paraphrases.
Thematic roles have sometimes been associated with a theory known as Case theory, as in many languages thematic roles are reflected in the case which the noun assumes. However, nowadays most linguists deny the grammatical visibility (i.e. the morpho-syntactic marking) of thematic roles, as most languages do not mark thematic roles homomorphically: For example, in German Nominative can realize Agent, Experiencer, or THEME. In contrast, other languages (like Thai) have no such markings at all and others (like English) employ word regularities to express the thematic constellations of a sentence.
Theta-criterion: in a sentence, each thematic role is assigned to a single noun phrase, and each noun phrase bears a unique thematic role. This is a proposed universal principle of grammar. (See also Universal grammar.) This feature is known as bi-uniqueness.
Thematic roles separate neoplastic (dummy) noun phrases, which lack a thematic role, such as it in it is going to rain, from meaningful noun phrases, which have one.