Chapter 93Argument Realization: Affix Indexing and Free NP Order

93.1 Overview

The predicate in Hokkaido Ainu carries obligatory person indexes that identify its core arguments: the sole argument S of an intransitive verb, and the agent A and patient O of a transitive verb. Overt noun phrases for those same roles are optional and, when present, stand in apposition to the index already on the verb rather than filling a case-marked argument slot. The result is a head-marking language in the sense of Nichols (1986): the predicate head encodes grammatical relations, and the dependent nominal does not. Satō (2025: 359–361) develops the contrast with dependent-marking languages such as Japanese, where the argument NP bears obligatory case particles. Bugaeva (2012: 461, 472) states the profile concisely: Ainu is agglutinating, polysynthetic, and head-marking, with verb-final constituent order and a mixed (basically tripartite) morphological alignment.

This chapter asks how S, A, and O are realised at the clause level: through bound indexes, through optional overt NPs, or through null. The person-affix paradigm itself — its cells, allomorphy, and the S/A/O distinctions — belongs to Chapter 62 (Architecture of the Personal-Affix System: The Four Persons and the S/A/O Paradigms) and the chapters that follow it. Morphological alignment is pursued in Chapter 72 (Tripartite, Nominative-Accusative, and the Central Alignment Debate). Pragmatic word order and topic fronting are treated in Chapter 92 (Basic Constituent Order and Head-Final Syntax) and Chapter 142 (Pragmatic Word-Order Permutation, Dislocation, and Argument Ellipsis). Reference tracking across clauses — zero anaphora, the fourth person in narrative, the absence of switch-reference morphology — is taken up in Chapter 139 (Reference Tracking and Argument Continuity).

93.2 Obligatory indexing; the verb alone is a complete sentence

Person indexes are not optional agreement controllers: they are the grammatical realisation of the argument itself. A finite verb without any overt NP is a complete, well-formed sentence. The intransitive inkar ‘look around’ with its first-singular prefix is self-sufficient as a one-word utterance:

Satō (2025: 359–360) states the principle directly: "grammatical relations (subject and object) … are not obligatory elements in Ainu; rather it is the personal affixes that are obligatory for the predicates." Bugaeva (2012: 472) formulates the same point as pro-drop with obligatory indexing: the language drops its overt NPs freely because the index already encodes the referent. A fuller transitive clause shows the same structure: without the NP cep 'fish', a=koyki 'catch' is a grammatically complete predication indexing a fourth-person agent and a third-person patient.

Independent personal pronouns — kani 'I', eani 'you' — are available for emphasis or contrast but are used more sparingly than their Japanese counterparts, since the verbal index already does the referential work Nakagawa (2024: 163–165); Bugaeva (2012: 472). They are a distinct word class from the bound indexes and are treated in Chapter 49 (Personal, Reflexive, and Emphatic Pronouns).

93.3 The structural status of overt NPs

When an overt NP does appear for a core role, its structural position relative to the verb is not that of a case-flagged argument filling a valency slot. Satō (2025: 363–365), working within Role and Reference Grammar, places the person index as the PRO inside the clausal CORE — the actual argument — and positions the co-referential NP outside the CORE as an optional, non-obligatory element. The Lakhota-parallel structure he gives for cep a=koyki has the same logical structure (LS) whether the NP is present or absent; the NP adds lexical specification without changing the underlying argument count.

An immediate formal consequence is that no case particle marks the S/A/O distinction on the NP itself. Ainu carries no markers corresponding to Japanese が or を for core roles Nakagawa (2024: 363); Bugaeva (2012: 472); Shibatani (1990: 22). Two NPs in the same clause — say, an agent and a patient — bear no formal distinction between them on the nominal. Role is readable from the verbal index and from contextual plausibility; a consequence explored in Chapter 92 (Basic Constituent Order and Head-Final Syntax) is that the preverbal NPs may appear in any sequence.

The same appositive status holds for possessor NPs: the possessee is obligatorily head-marked by a person prefix, so "pronominal possessor NPs are normally not used and even nominal possessor NPs may easily be omitted if contextually recoverable" Bugaeva (2012: 486). Ijäs (2023) captures the same pattern pedagogically, describing the verb as having obligatory "pockets" for its arguments and the overt NP as redundant: "you would need to convey the same information twice but that would be very uneconomical."

93.4 Null and zero arguments

"It is not necessary in Ainu for a noun phrase that is clear from the context to appear in a sentence, and such a noun phrase is not even represented by a pronoun; even if a verb takes two objects, it is normal for only one of them to be present" — Bugaeva (2022) (ch.14, before ex.75). Nakagawa (2024: 361) formalises this in the sentence template: a NP "need not be present in the sentence as long as it can be supplied meaningfully from context." The missing argument is read as a zero anaphor — not a phonologically null pronoun alongside the index, but the index itself satisfying the valency slot with no additional NP exponency.

A particularly clear case arises with three-place verbs. A verb hosts at most one subject index and one object index (Chapter 62 (Architecture of the Personal-Affix System: The Four Persons and the S/A/O Paradigms); Chapter 66 (Object Indexing: Monotransitive and Ditransitive Clauses)), so the third argument of a ditransitive — typically the theme — is never indexed and appears only as an optional bare NP or is null. Its reference remains unambiguous: "verbal valency guarantees the interpretation of anaphoric reference without any personal affix" Satō (2025: 368–369). The following clause is the second in a two-sentence passage; the preceding clause establishes the theme (a sweet). The second clause drops it entirely, leaving only the human recipient and the first-singular agent overt or indexed:

The third person is zero-marked throughout the paradigm: the bare verb stem without any affix expresses a third-person argument. Satō (2025: 369) argues that recognising a possessive prefix a= (fourth person) already commits the analyst to a zero third-person affix in the slot that a= contrasts with. Nakagawa (2024: 169) describes the same paradigm without explicitly positing a zero affix ‹contested›; the status of the zero is examined in Chapter 62 (Architecture of the Personal-Affix System: The Four Persons and the S/A/O Paradigms). A community observation corroborates the zero-3rd-person analysis: "the bare verb form = 3SG = citation/dictionary form" and "using a possessive already concedes a zero 3rd person" (nukopoli, aynu-corpora Discord, 2024-12-25, asserted) aynu-corpora Discord (2023–2026) ‹corpus-confirmed›.

93.5 Modes of argument realisation

Satō (2025: 371, 373–374) provides the master inventory of how a core argument can be realised in a head-marking Ainu clause. The five modes are not mutually exclusive — noun incorporation combines bound morphology with what would otherwise be an NP slot — but they represent the primary structural options:

Satō (2025: 371) draws a theoretical conclusion from this inventory: because argument fulfilment is "sometimes by syntactic means and sometimes by morphological means," the syntax/morphology boundary "is blurred in Ainu," a consequence of its head-marking character. Mode 4 in particular — the theme as bare NP without an index — "partly shows a dependent-marking characteristic" while remaining under head-marking control. Satō (2025: 366–367) further uses the attested A-incorporation pattern (ku=koy-yanke 'the waves wash me ashore') to argue against Baker's ((Baker 1988: 229–232)) syntactic head-movement theory of incorporation: since the person index already anchors the argument inside the verb, incorporation need not be derived by NP movement.

93.6 Are overt NPs arguments? The appositional-NP debate

Whether overt NPs that co-occur with verbal indexes should be analysed as true arguments of the verb or as appositives to pronominal arguments already residing on the verb is an open analytical question that the literature on Ainu explicitly engages ‹contested›.

The pronominal-argument position (associated with Jelinek 1984 and Baker 1988/1996, as framed in Bugaeva (2022) ch.1 §4.3) holds that in head-marking languages the bound indexes are the clause's actual arguments and co-referential NPs are mere appositives that lexically qualify them — adjuncts, not arguments. Applied to Ainu, this analysis predicts that an overt NP should be freely omissible (attested), freely ordered (attested), uncased (attested), and potentially discontinuous (attested for floating quantifiers; Chapter 92 (Basic Constituent Order and Head-Final Syntax)). As a theoretical classification it would place Ainu in the nonconfigurational company of Mohawk or Lakhota. The full battery of diagnostics is examined in Chapter 94 (Pro-Drop, (Non)configurationality, and the Pronominal-Argument Debate).

Bugaeva (2022) (ch.1 §4.3) names and entertains the pronominal-argument position but does not adopt it for Ainu. Her preferred account, aligned with Mithun (2003, cited in Bugaeva 2022 ch.1 §4.3), is shared argumenthood: bound pronouns and coreferential NPs jointly share argumenthood, neither alone being the sole argument. The Ainu-specific evidence she marshals is the location-class noun (see §6 below): when both A and O are third-person and therefore zero-indexed, what disambiguates the two roles is the semantic class of one of the NPs — specifically whether it is a locative-type noun. If NPs were pure appositives with no grammatical traction, their semantic class would have no leverage on role assignment; the fact that it does points toward retained argumenthood.

Satō (2025: 363–365), working in Role and Reference Grammar, gives a third structural description: the person index is the PRO inside the clausal CORE, and the co-referential NP sits outside the CORE — architecturally close to the pronominal-argument analysis but without endorsing the PAH label or a nonconfigurational classification. Satō does not invoke Jelinek's Pronominal Argument Hypothesis or describe Ainu as nonconfigurational; the account is head-marking with an optional external appositive.

The current consensus is partial. That Ainu is head-marking, pro-drop, without core case, and with freely ordered optional overt NPs is uncontested. Whether those NPs are appositive adjuncts to pronominal arguments (Jelinek/Baker line) or share argumenthood with the indexes (Mithun/Bugaeva line) is contested, and no Ainu specialist has published a dedicated pronominal-argument study; the framing reaches Ainu only through Bugaeva's and Satō's typological treatments, and Bugaeva's own preferred position argues against the pure appositive reading. The chapter-length treatment is in Chapter 94 (Pro-Drop, (Non)configurationality, and the Pronominal-Argument Debate).

93.7 The location-class noun as role disambiguation

When both the agent and the patient of a transitive clause are third person — zero-indexed, no case marking, no fixed order — the verbal indexes supply nothing to distinguish agent from patient. This is the empirical gap at the centre of Bugaeva's counter-argument to the pure appositive analysis. Nakagawa (2022) (ch.14) documents the resolution: what disambiguates the roles is the location-class status of a noun. Locative relational nouns such as or ‘place of’, ka ‘surface of’, and corpok ‘below’ — attached after an NP — mark that NP as a Location argument, leaving the other NP unambiguously as the theme or patient.

The disambiguation is lexical and semantic, not morphological: it depends on the inherent or augmented location-class status of one NP, not on a separate case affix. As Bugaeva (2022) (ch.1 §4.4) notes, the mechanism is "particularly relevant when one of the arguments is omitted" — when the non-location NP is null, the locative NP's class alone tells the listener what role the missing argument fills. The contrast with Nivkh is instructive: Nivkh also lacks case on S/O but fixes the object immediately preverbal and signals it by a consonant mutation; Ainu uses neither device, relying on indexing and the location class instead Nakagawa (2022). The locative noun system and its postpositional extensions are treated in Chapter 52 (Relational and Spatial (Locative) Nouns and Their Possessed Forms) and Chapter 53 (Postpositions, Local Case, Motion Events, Comitative, and Instrumental).

93.8 Reference tracking: zero anaphora and the fourth person

Because arguments are indexed on the verb and overt NPs are optional, participant continuity across a narrative rests primarily on zero anaphora plus the verbal indexes themselves; pronouns are not routinely redeployed to maintain reference. Overt NP re-mention is reserved for (re)introduction, contrast, or scene change Bugaeva (2022) (ch.14); Nakagawa (2024: 361).

The fourth person does additional tracking work in narrative. In oral texts it marks the protagonist's or quoted speaker's first person as distinct from both the plain third-person cast and the narrating speaker's first singular, functioning as an obviative-like "other first person" Nakagawa (2024: 177–179); Bugaeva (2008: 40–43). An observed instance: in an uwepeker telling, the narrator alternates a= and ku= to keep the in-story protagonist's speech separate from the narrator's own voice (thegodofneet, aynu-corpora Discord, 2024-07-04, asserted) aynu-corpora Discord (2023–2026). This alternation is consistent with Bugaeva (2008: 40–43)'s logophoric analysis of the fourth-person quotation use and with Nakagawa (2024: 174–179)'s narrative first-person account. The fourth person's full referential range and its interaction with topic-marking anakne ‘as for’ are treated in Chapter 67 (The Indefinite/Fourth Person: Forms, Reference, and Agent-Defocusing), Chapter 68 (Honorific and Logophoric Uses of the Fourth Person), and Chapter 150 (First-Person Narration, the Logophoric Fourth Person, and Reported Discourse); the wider reference-tracking apparatus — zero anaphora, clause chaining, and the absence of morphological switch-reference — is taken up in Chapter 139 (Reference Tracking and Argument Continuity) and Chapter 131 (Clause Linkage in Ainu: Typology and Inventory).