Agent (grammar)
In linguistics
Linguistics is the scientific study of human language. Linguistics can be broadly broken into three categories or subfields of study: language form, language meaning, and language in context....

, a grammatical agent is the cause or initiator of an event. Agent is the name of the thematic role
Thematic role
Thematic role is a linguistic notion, which may refer to:* Theta role * Thematic relation...

 (also known as the thematic relation). The word comes from the present participle agens, agentis ("the one doing") of the Latin verb agere, to "do" or "make".

Typically, the situation is denoted by a sentence
Sentence (linguistics)
In the field of linguistics, a sentence is an expression in natural language, and often defined to indicate a grammatical unit consisting of one or more words that generally bear minimal syntactic relation to the words that precede or follow it...

, the action by a verb
A verb, from the Latin verbum meaning word, is a word that in syntax conveys an action , or a state of being . In the usual description of English, the basic form, with or without the particle to, is the infinitive...

 in the sentence, and the agent by a noun phrase
Noun phrase
In grammar, a noun phrase, nominal phrase, or nominal group is a phrase based on a noun, pronoun, or other noun-like word optionally accompanied by modifiers such as adjectives....


For example, in the sentence "Jack kicked the ball", Jack is the agent. In certain languages, the agent is declined
In linguistics, declension is the inflection of nouns, pronouns, adjectives, and articles to indicate number , case , and gender...

 or otherwise marked to indicate its grammatical role. In Japanese
Japanese language
is a language spoken by over 130 million people in Japan and in Japanese emigrant communities. It is a member of the Japonic language family, which has a number of proposed relationships with other languages, none of which has gained wide acceptance among historical linguists .Japanese is an...

, for instance, the agent is typically affixed with ga or wa (the hiragana
is a Japanese syllabary, one basic component of the Japanese writing system, along with katakana, kanji, and the Latin alphabet . Hiragana and katakana are both kana systems, in which each character represents one mora...

 が, は). Although Modern English
English language
English is a West Germanic language that arose in the Anglo-Saxon kingdoms of England and spread into what was to become south-east Scotland under the influence of the Anglian medieval kingdom of Northumbria...

 does not mark grammatical role, agency is informally represented using certain conventions; for instance, with the morpheme
In linguistics, a morpheme is the smallest semantically meaningful unit in a language. The field of study dedicated to morphemes is called morphology. A morpheme is not identical to a word, and the principal difference between the two is that a morpheme may or may not stand alone, whereas a word,...

s "-ing", "-er", or "-or", as in "eating", "user", or "prosecutor". (Cf. agent noun
Agent noun
In linguistics, an agent noun is a word that is derived from another word denoting an action, and that identifies an entity that does that action. For example, "driver" is an agent noun formed from the verb "drive". The endings "-er", "-or", and "-ist" are commonly used in English to form agent...


The notion of agency is easy to grasp intuitively but notoriously difficult to define: typical qualities that a grammatical agent often has are that it has volition
Volition may refer to:*Volition , the cognitive process by which an individual decides on and commits to a particular course of action...

, is sentient or perceives, causes a change of state, or moves. The linguist David Dowty
David Dowty
David Dowty is a linguist known primarily for his work in semantic and syntactic theory, and especially in Montague grammar and Categorial grammar. Dr. Dowty is a professor emeritus of linguistics at the Ohio State University.-Publications:...

 included these qualities in his definition of a Proto-Agent, and proposed that the nominal with the most elements of the Proto-Agent and the fewest elements of the Proto-Patient tends to be treated as the agent in a sentence. This solves problems that most semanticists have with deciding on the number and quality of thematic roles. For example, in the sentence His energy surprised everyone, His energy is the agent, even though it does not have most of the typical agent-like qualities such as perception, movement, or volition. Even Dowty's solution fails for verbs expressing relationships in time:

(1) April precedes May. vs: (2) May follows April.

Here what is agent and what is patient must be specified for each individual verb.

The grammatical agent is often confused with the subject
Subject (grammar)
The subject is one of the two main constituents of a clause, according to a tradition that can be tracked back to Aristotle and that is associated with phrase structure grammars; the other constituent is the predicate. According to another tradition, i.e...

, but these two notions are quite distinct: the former is based explicitly on its relationship to the action or event expressed by the verb
A verb, from the Latin verbum meaning word, is a word that in syntax conveys an action , or a state of being . In the usual description of English, the basic form, with or without the particle to, is the infinitive...

, whereas the latter is based on the flow of information
Information flow
In discourse-based grammatical theory, information flow is any tracking of referential information by speakers. Information may be new, just introduced into the conversation; given, already active in the speakers' consciousness; or old, no longer active...

, word order, and importance to the sentence. In a sentence such as "The boy kicked the ball", "the boy" is the agent and the subject. However, when the sentence is rendered in the passive voice
Passive voice
Passive voice is a grammatical voice common in many of the world's languages. Passive is used in a clause whose subject expresses the theme or patient of the main verb. That is, the subject undergoes an action or has its state changed. A sentence whose theme is marked as grammatical subject is...

, "The ball was kicked by the boy", "the ball" is the grammatical subject, but "the boy" is still the agent. Many sentences in English and other Indo-European languages
Indo-European languages
The Indo-European languages are a family of several hundred related languages and dialects, including most major current languages of Europe, the Iranian plateau, and South Asia and also historically predominant in Anatolia...

have the agent as subject.
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