||It has been suggested that this article be merged into Ergative verb. (Discuss) Proposed since March 2013.|
In linguistics, an unaccusative verb is an intransitive verb whose (syntactic) argument is not a (semantic) agent; that is, it does not actively initiate, or is not actively responsible for, the action of the verb; or that treats the argument like the accusative argument of a transitive verb. Unaccusative verbs thus contrast with unergative verbs. An unaccusative verb's subject is semantically similar to the direct object of a transitive verb, or to the subject of a verb in the passive voice. English unaccusative verbs include die and fall, but not run or resign, which are unergative. They are called unaccusative because, although the subject has the semantic role of a patient, it is not assigned accusative case.
In nominative–accusative languages, the accusative case, which marks the direct object of transitive verbs, usually represents the non-volitional argument (often the patient). But for unaccusative verbs, the subject is non-volitional and yet is not marked by the accusative.
Deriving unaccusativity 
The derivation of the core properties of unaccusative constructions from a set of principles is one of the topmost issues of the agenda of modern syntax since the seminal work by Perlmutter 1978 (cf. Burzio 1986 and Hale-Keyser 2003 for landmark proposals). More specifically, the first approach arrived at an important consequence constituting an analogy between English passive voice constructions and unaccusative constructions whereas in the second approach a more radical theory was proposed based on the analysis of expletive there stemming from the sentences with the copula suggested in Moro 1997.
From unaccusative constructions it is possible to derive unaccusative transitive constructions complete with ergative morphology:
- मौसम फिर पलटा → मौसम ने फिर पलटा खाया
- mausam phir palaTā → mausam ne phir palTā khāyā
- weather again flipped → weather ERG again flip ate
- 'The weather flipped again.'
Tests for unaccusativity 
As mentioned above, the unaccusative/unergative split in intransitive verbs can be characterized semantically. Unaccusative verbs tend to express a telic and dynamic change of state or location, while unergative verbs tend to express an agentive activity (not involving directed movement). While these properties define the "core" classes of unaccusatives and unergatives, there are intermediate classes of verbs whose status is less clear (for example, verbs of existence, appearance, or continuation, verbs denoting uncontrolled processes, or motion verbs).
A number of syntactic criteria for unaccusativity have also been identified. The most well-known test is auxiliary selection in languages that use two different temporal auxiliaries (have and be) for analytic past/perfect verb forms (e.g. German, Dutch, French, Italian; even Early Modern English). In these languages, unaccusative verbs combine with be, while unergative verbs combine with have.
- unaccusative: Je suis tombé. lit. "I am fallen." (= "I have fallen.")
- unergative: J'ai travaillé. "I have worked."
- unaccusative: È arrivato. lit. "[He] is arrived." (= "He has arrived.")
- unergative: Ha telefonato. "[He] has phoned."
From one language to another, however, synonymous verbs do not always select the same auxiliary, and even within one language, a single verb may combine with either auxiliary (either depending on the meaning/context, or with no observable semantic motivation, sometimes depending on regional variation of the language). The auxiliary selection criterion therefore also identifies core classes of unaccusative and unergatives (which show the least variation within and across languages) and more peripheral classes (where variation and context effects are observed).
Other tests that have been studied involve passivization (see Impersonal passive voice), ne/en cliticization in Italian and French, and impersonal, participial, and resultative constructions in a wide range of languages. In Japanese, the grammaticality of sentences that appear to violate syntactic rules may signal the presence of an unaccusative verb. According to transformational models of grammar, such sentences contain a trace located in the direct object position that helps to satisfy the mutual c-command condition between numeral quantifiers and the noun phrases they modify (Tsujimura, 2007).
Unaccusativity in English 
Modern English only uses one perfect auxiliary (have), although archaic examples like "He is fallen/come" reflect the use of be with unaccusative verbs in earlier stages of the language.
The identification of unaccusative verbs in English is therefore based on other criteria. For example, many unaccusatives alternate with a corresponding transitive construction where the unaccusative subject appears in direct object position:
- The ice melted. ≈ The sun melted the ice.
- The window broke. ≈ The golf ball broke the window.
Unaccusative past participles can be used as nominal modifiers with active meaning, while unergative past participles cannot:
- unaccusative: the melted snow, the departed guests, the fallen soldiers
- unergative: *the shouted victim, *the slept child, *the hesitated leader
Finally, unaccusative subjects can generally be modified by a resultative adjunct. This is a property shared by direct objects and passive subjects, but not shared by the subjects of unergative and transitive verbs.
- unaccusative subject: The vase broke into pieces.
- direct object: John broke the vase into pieces.
- passive subject: The vase was broken into pieces.
- unergative subject: *John dined full/to death/two pounds heavier.
- subject of transitive verb: *John ate the brownies full/to death/two pounds heavier.
- Lexicon of Linguistics (Utrecht institute of Linguistics)
- Burzio, Luigi (1986). Italian Syntax: A Government-Binding Approach. Dordrecht: Reidel.
- Everaert, M.; van Riemsdijk, H; Goedemans, R. (eds) 2006 The Blackwell Companion to Syntax, Volumes I–V, Blackwell, London. See "copular sentences" and "existential sentences and expletive there" in Volume II
- Hale, K.; Keyser, J. (2002) Prolegomena to a theory of argument structure, Linguistic Inquiry Monograph, 39, MIT Press, Cambridge, Massachusetts.
- Levin, Beth; Malka Rappaport-Hovav (1994). Unaccusativity: At the Syntax-Semantics Interface. Cambridge, MA: MIT Press.
- Moro, A. 1997 The raising of predicates. Predicative noun phrases and the theory of clause structure, Cambridge Studies in Linguistics, Cambridge University Press, Cambridge, England.
- Perlmutter, David M. (1978). "Impersonal passives and the Unaccusative Hypothesis". Proc. of the 4th Annual Meeting of the Berkeley Linguistics Society. UC Berkeley. pp. 157–189.
- Sorace, Antonella (2000). "Gradients in auxiliary selection with intransitive verbs". Language (Linguistic Society of America) 76 (4): 859–890. doi:10.2307/417202. JSTOR 417202.
- Tsujimura, Natsuko (2007). An introduction to Japanese linguistics (second edition). Malden, MA: Blackwell.
See also 
- Unaccusative verb
- Unergative verb — opposite of unaccusative
- Reflexive verb
- Deponent verb
- Impersonal passive voice