In nominative-accusative languages (like English) the agent of a transitive verb and the solitary argument of an intransitive verb are treated alike. They are both called the subject and they have a syntactic/morphological parity which might be word order or grammatical case (nominative). The object of a transitive verb (patient) is treated differently (accusative).
- We run marathons. We sleep.
- They remember us.
In ergative-absolutive languages (e.g. Basque) it is the solitary argument of an intransitive verb and the object of a transitive verb that are treated the same (morphologically or syntactically). In languages with case, solitary argument of an intransitive verb and the object of a transitive verb would have absolutive case. The agent of a transitive verb is treated differently (ergative case).
Some languages have both ergative and accusative morphology.
