Split ergativity

Nominative-accusative languages (including European languages, with the notable exception of Basque) treat both the actor in a clause with a transitive verb and the experiencer in a clause with an intransitive verb in the same way grammatically. If the language uses case markers, they take the same case. If it uses word order, it is parallel.

For example, consider these two English sentences:

• Jane was chasing John.
• Jane was sweating.

The grammatical role of "Jane" is identical. In both cases, "Jane" is the subject.

In ergative-absolutive languages (including the Basque, Georgian, Greenlandic and Mayan languages), there is a different pattern. The patient (or target) of a transitive verb and the experiencer of an intransitive verb are treated the same grammatically. If the two sentences above were expressed in an ergative language, "John" in the former and "Jane" in the latter would be parallel grammatically. Also, a different form (the ergative) would be used for "Jane" in the first sentence. (There is no easy way to represent that construction in English.)

In split ergative languages, some constructions pattern with nominative-accusative, and others with ergative-absolutive.

The split is usually conditioned by one of the following:

1. The presence of a discourse participant (a first or second person) in the proposition. The Australian language Dyirbal behaves ergatively in all morphosyntactic contexts unless one of those is involved. When a first- or second-person pronoun appears, however, it is marked according to a nominative–accusative pattern (with the least-marked case, when it is the agent or intransitive, or with the most marked case, when it is the patient). That can be explained in terms of the high animacy of a first- or second-person speaker in the animacy hierarchy.
2. The use of certain tenses and/or aspects in the verb. The Indo-Iranian family, for example, shows a split between the perfective and the imperfective aspect. A verb in the perfective aspect causes its arguments to be marked by an ergative pattern, and the imperfective aspect triggers accusative marking. (Both related languages and others tend to associate the past tense and/or perfect aspect with ergativity.)
3. The type of marking involved. Some languages (including various Austronesian languages of New Guinea such as Sinaugoro) have an ergative–absolutive pattern with respect to the marking of case marking but a nominative–accusative pattern with respect to agreement.
4. The agentivity of the intransitive subject. In languages like Dakota, arguments of active verbs, such as to run, are marked like transitive agents, as in accusative languages, but arguments of inactive verbs, such as to stand are marked like transitive objects, as in ergative languages. Languages with such a marking are known as split-S languages and are formally a subtype of active languages.
5. Pragmatic considerations or for emphasis, contrast, or clarity. In certain Tibeto-Burmese languages, elicited data has consistent ergative, aspectually split-ergative or active-stative case marking pattern, and in natural discourse the “ergative” marking is found only in some clauses, often a minority, usually with some pragmatic sense of emphasis or contrast (DeLancey, 2011).[2]