Thematic roles are crucial for understanding sentence meaning beyond grammar. They describe how participants relate to predicates, like who does what to whom. These roles help us grasp sentence semantics regardless of syntax.

Case grammar, proposed by Charles Fillmore, uses thematic roles to explain sentence meaning. It focuses on semantic relationships between predicates and arguments, not just syntax. This theory influenced later ideas about semantic roles and argument structure.

Thematic Roles

Thematic roles and semantic relationships

• Thematic roles are semantic categories that describe the relationship between a predicate (verb) and its arguments (noun phrases) in a sentence
• Capture the underlying semantic roles played by the arguments in the event or state described by the predicate, such as who does what to whom, where, when, and how
• Help identify the participants in a situation and their roles (agent, patient, theme), regardless of their syntactic position (subject, object)
• Provide a way to represent the semantic structure of a sentence, independent of its surface syntactic structure (active vs passive voice)
• Important for understanding the meaning of a sentence beyond its grammatical form and word order

Assignment of thematic roles

• Agent: participant that intentionally initiates or carries out the action expressed by the predicate ("John kicked the ball")
• Patient: participant that undergoes a change of state or is affected by the action expressed by the predicate ("The vase was broken by the cat")
• Theme: participant that is moved, changed, or located as a result of the action expressed by the predicate ("Mary gave the book to John")
• Experiencer: participant that experiences a sensory, cognitive, or emotional state expressed by the predicate ("Sarah loves chocolate")
• Location: place where the action or state expressed by the predicate occurs ("The cat is sitting on the mat")
• Instrument: object or force used to perform the action expressed by the predicate ("He cut the rope with a knife")
• Recipient: participant that receives something as a result of the action expressed by the predicate ("John gave the book to Mary")

Thematic vs grammatical roles

• Grammatical roles (subject, direct object, indirect object) are syntactic categories that describe the function of a noun phrase in a sentence based on its position and morphological marking
• Thematic roles are semantic categories that describe the relationship between a predicate and its arguments based on the meaning of the predicate and the semantic roles of the participants
• The same thematic role can be assigned to different grammatical roles in different sentences ("John (agent, subject) kicked the ball" vs "The ball (patient, subject) was kicked by John")
• The same grammatical role can be assigned to different thematic roles in different sentences ("John (subject, agent) kicked the ball" vs "John (subject, experiencer) loves Mary")

Case Grammar and Thematic Roles

Case grammar and thematic roles

• Case grammar is a linguistic theory proposed by Charles Fillmore in the 1960s that aims to describe the underlying semantic structure of sentences using thematic roles (also called semantic cases or deep cases)
• Posits that the meaning of a sentence is determined by the semantic relationships between the predicate and its arguments, rather than by the syntactic structure alone
• Each predicate is associated with a set of semantic cases (thematic roles) that its arguments can fill, considered to be universal and innate rather than language-specific
• Semantic cases in case grammar are similar to modern thematic roles:
  • Agentive case (agent role)
  • Dative case (recipient or experiencer role)
  • Locative case (location role)
  • Objective case (patient or theme role)
• Provides a way to represent the semantic structure of a sentence independently of its syntactic structure (active vs passive voice)
• Case frames specify the semantic cases required by a particular predicate, regardless of their syntactic realization
• Has influenced later theories of semantic roles and argument structure (theta theory, neo-Davidsonian event semantics)