causativealternation

Causative alternation is a linguistic phenomenon in which a subset of verbs can appear in two related syntactic forms: a transitive causative construction and an intransitive anticausative (or inchoative) construction. In the anticausative use, the subject undergoes a change of state or a event without an overt external causer. In the causative use, an external agent causes the event to occur, producing a sentence in which the patient names the affected object and a distinct causer is added as the agent.

Across languages, the two forms often share the same verb root but differ in argument structure and semantics. The same event is interpreted as either self-initiated (the patient acts upon itself) or caused by an external force. This alternation provides insight into event structure, valency (the number and type of arguments), and the relationship between lexical meaning and syntax.

Examples in English illustrate the pattern:

- The door opened. The waiter opened the door.

- The ice melted. The sun melted the ice.

- The window broke. The child broke the window.

In English, causative alternation is largely lexical and syntactic rather than morphologically marked. In other languages, the alternation may be encoded with dedicated causative or anticausative morphology, verb-specific patterns, or changes in voice or valency. Causative alternation is a central topic in the study of diathesis alternations, event structure, and the syntax–semantics interface.