Editing Igbo language (section)

== Grammatical relations ==
Igbo does not mark overt case distinctions on nominal constituents and conveys grammatical relations only through [[word order]]. The typical Igbo sentence displays subject-verb-object (SVO) ordering, where the subject is understood as the sole argument of an intransitive verb or the agent-like (external) argument of a transitive verb. Igbo thus exhibits [[Nominative–accusative language|accusative]] [[Morphosyntactic alignment|alignment]].

It has been proposed, with reservations, that some Igbo verbs display ergativity on some level, as in the following two examples:<ref name=":0" />

{{interlinear|number=(4)
|Nnukwu mmīri nà-ezò n'iro.
|big water AUX-fall PREP-outside
|'Heavy rain is falling outside.'}}

{{interlinear|number=(5)
|Ọ nà-ezò nnukwu mmīri n'iro.
|it AUX-fall big water PREP-outside
|'Heavy rain is falling outside.'}}

In (4), the verb has a single argument, ''nnukwu mmīri'', which appears in subject position, and in the transitive sentence (5), that same argument appears in the object position, even though the two are semantically identical. On this basis, authors such as Emenanjuo (2015) have posited that this argument is an absolutive and that Igbo therefore contains some degree of ergativity.

However, others disagree, arguing that the relevant category is not alignment but underlying argument structure; under this hypothesis, (4) and (5) differ only in the application of a transformation and can be accounted for entirely by the [[Unaccusative verb|unaccusative]] hypothesis and the [[Extended Projection Principle]];<ref name=":3">{{Cite journal|last=Nwachukwu|first=P. Akujuoobi |date=September 1987 |title=The Argument Structure of Igbo Verbs |journal=Lexicon Project Working Papers |volume=18 |archive-url=https://web.archive.org/web/20231221030515/https://manfredi.mayfirst.org/Nwachukwu1987MIT.pdf |archive-date=2023-12-21 |url=https://manfredi.mayfirst.org/Nwachukwu1987MIT.pdf}}</ref> the nominal argument is generated in object position, and either it is raised to the subject position, as in (4), or the subject position is filled with a [[pleonastic pronoun]], as in (5).