Editing Nominative–accusative alignment (section)

==Relevant theory==

===Optimality theory===
	One of the ways in which the production of a nominative–accusative case marking system can be explained is from an [[Optimality Theory|Optimality Theoretic]] perspective. Case marking is said to fulfill two functions, or constraints: an identifying function and a distinguishing function.<ref name=hoopALM>de Hoop, Helen and Malchukov, Andrej L. (2008) "Case-marking strategies". ''Linguistic Inquiry''.</ref> The identifying function is exemplified when case morphology encodes (identifies) specific [[semantics|semantic]], thematic, or [[pragmatics|pragmatic]] properties or information about the nominal argument. Accusative case in the position of the direct object, for example, can be a strong identifier of [[patient (grammar)|patienthood]]. The distinguishing function is used to distinguish between the core arguments, the subject and the object, of a transitive clause. [[Helen de Hoop]] and [[Andrej Malchukov]] explain the motivation and need for the distinguishing function in "Case marking strategies":
{{blockquote|When a two-place predicate R(x,y) is used to describe an event involving two participants, usually an agent and a patient, it is of utmost importance to avoid ambiguity as  to which noun phrase corresponds to the first argument  x  (the agent) and which to the second argument  y (the patient). For this purpose, case can be used to mark one of the arguments. If one argument is case marked, this already suffices for the purpose of disambiguation. Thus, from the distinguishing perspective, there is no need to case mark both arguments. Neither would it be necessary to case mark the one and only argument of a one-place (intransitive) predicate. Indeed, it has been argued that in many nominative–accusative case systems only the y is case marked (with accusative case) while the x  remains morphologically unmarked.<ref name=hoopALM/>}}
It is rare for case to serve only the distinguishing function, which overlaps greatly with the ‘identify’ function. Other ways of disambiguating the arguments of a transitive predicate (subject agreement, word order restriction, context, intonation, etc.) may explain this cross-linguistic observation. De Hoop and Malchukov argue that case systems that are completely based on the identification function must be richer in case morphology compared to languages based mainly on the distinguishing function.

===Functional pressure===

One theory that has been posited to account for the occurrence of accusative systems is that of functional pressure. When applied to languages, this theory operates around the various needs and pressures on a speech community. It has been suggested that languages have evolved to suit the needs of their users.These communities will develop some functional system to meet the needs that they have. So, it has been proposed that the accusative system arose from a functional pressure to avoid ambiguity and make communication a simpler process.<ref name=bates>Bates, E., & MacWhinney, B. (1982) ''Functionalist approaches to grammar''. In E.Wanner, & L. Gleitman (Ed.), ''Language acquisition: The state of the art''. New York:
Cambridge University Press.</ref><ref name=fedz>Fedzechkina, Maryia & Jaeger, T. Florian & Newport, Elissa L. (2011) "Functional Biases in Language Learning: Evidence from Word Order and Case-Marking Interaction". ''Cognitive Science''.</ref>

It is useful for languages to have a means of distinguishing between subjects and objects, and between arguments A, S, and O. This is helpful so that sentences like "Tom hit Fred" cannot be interpreted as "Fred hit Tom." [[tripartite language|Tripartite]] alignment systems accomplish this differentiation by coding S, A and O all differently. However, this is not structurally economical, and tripartite systems are comparatively rare, but to have all arguments marked the same makes the arguments too ambiguous. Alongside the principle of distinguishability seems to operate a principle of economy. It is more efficient to have as few cases as possible without compromising intelligibility. In this way the dual pressures of efficiency and economy have produced a system which patterns two kinds of arguments together a third separately. Both accusative and ergative systems use this kind of grouping to make meaning clearer.

<!---Preliminary kept here for further use in other articles
==Sociolinguistics and nominative–accusative alignment==  
{{Off topic|date=May 2020}}
===Collapse of English second-person pronouns===
{| align=left class="wikitable" style="margin-right:2em"
! Case
! Old English
! Early Modern English
! Modern English
|-
! SG <small>[[Nominative case|NOM]]</small>
| þu || thou || you
|-
! SG <small>[[Accusative case|ACC]]</small>
| þe || thee || you
|-
! SG DAT
| þe || thee || you
|-
! SG GEN
| þin || thy/thine || your
|-
! PL <small>[[Nominative case|NOM]]</small>
| ge || ye || you
|-
! PL <small>[[Accusative case|ACC]]</small>
| eow || you || you
|-
! PL DAT
| eow || you || you
|-
! PL GEN
| eower || your || your
|}

Because pronominal reference systems to the speaker, addressee, and a third person are so common (some argue [[universal grammar|universal]]) cross-linguistically, it would seem that pronoun systems are quite stable. However, the changes involved in [[grammatical person|second-person]] pronouns in English call this stability into question and highlight the significance of social forces in language development. The spread of [[feudalism|feudalistic]] ideology caused many European languages to develop two sets of second-person singular pronouns in order to reflect hierarchy. Therefore, pronouns encoded not only person or number, but also the speaker's assessment of the addressee's status and the speaker-addressee relationship.

From the thirteenth century, the [[Middle English]] plural pronouns 'ye' (nominative) and 'you' (accusative) were used to address single individuals in upper-class or courtly contexts.<ref name=nau>Fitzmaurice, Susan. "Politeness in Early Modern English". http://jan.ucc.nau.edu/~eng121-c/politenessin%20AME.htm</ref> As a result, there were two sets of second-person singular pronouns, and the alternative singular pronouns 'thou' (nominative) and 'thee' (accusative) became increasingly associated with lower status. These distinctions had become established indices of social status by the fifteenth century, and they also developed as indicators of interpersonal relationships at this time: 'you' might show emotional distance or be used in a public setting, 'thou' familiarity/intimacy in a private setting.<ref name=nau/> We see vestiges of this distinction in languages like German or French that have retained the [[T-V distinction]], but second-person pronouns in these languages, as well as in Italian, Serbo-Croatian, and Swedish, have also begun to undergo change.<ref name=feminist>Cameron, Deborah. (1998) ''The feminist critique of language: a reader''. Psychology Press.</ref>

Under the pressure of social structural changes and movement towards [[egalitarianism|egalitarian]] ideology, the English second-person singular pronouns later collapsed to a single term, 'you'.<ref name=feminist/> This contraction erased all visible morphological distinction between nominative and accusative case in the second person, effectively sacrificing distinguishability for economy.--->