Editing Ergative–absolutive alignment (section)

===Optional ergativity===

Many languages with ergative marking display what is known as ''optional ergativity'', where the ergative marking is not always expressed in all situations. McGregor (2010) gives a range of contexts when we often see optional ergativity, and argues that the choice is often not truly ''optional'' but is affected by [[semantics]] and [[pragmatics]]. Unlike [[split ergativity]], which occurs regularly but in limited locations, optional ergativity can occur in a range of environments, but may not be used in a way that appears regular or consistent.

Optional ergativity may be motivated by:
* The [[animacy]] of the subject, with more ''animate'' subjects more likely to be marked ergative
* The [[semantics]] of the verb, with more ''active'' or ''transitive'' verbs more likely to be marked ergative
* The [[grammatical structure]] or [tense-aspect-mood]

Languages from Australia, New Guinea and Tibet have been shown to have optional ergativity.<ref>[[William B. McGregor|McGregor]] (2010) Optional ergative case marking systems in a typological-semiotic perspective. ''Lingua'' 120: 1610–1636</ref>