A passive voice construction is a grammatical voice construction that is found in many languages. In a clause with passive voice, the grammatical subject expresses the theme or patient of the main verb - that is, the person or thing that undergoes the action or has its state changed. This contrasts with active voice, in which the subject has the agent role. For example, in the passive sentence "The tree was pulled down", the subject (the tree) denotes the patient rather than the agent of the action. In contrast, the sentences "Someone pulled down the tree" and "The tree is down" are active sentences.
Typically, in passive clauses, what is usually expressed by the object (or sometimes another argument) of the verb is now expressed by the subject, while what is usually expressed by the subject is either deleted or is indicated by some adjunct of the clause. Thus, turning an active verb into a passive verb is a valence-decreasing process ("detransitivizing process"), because it turns transitive verbs into intransitive verbs. This is not always the case; for example in Japanese a passive-voice construction does not necessarily decrease valence.
Many languages have both an active and a passive voice; this allows for greater flexibility in sentence construction, as either the semantic agent or patient may take the syntactic role of subject. The use of passive voice allows speakers to organize stretches of discourse by placing figures other than the agent in subject position. This may be done to foreground the patient, recipient, or other thematic role; it may also be useful when the semantic patient is the topic of on-going discussion. The passive voice may also be used to avoid specifying the agent of an action.
Different languages use various grammatical forms to indicate passive voice.
In some languages, passive voice is indicated by verb conjugation, specific forms of the verb. Examples of languages that indicate voice through conjugation include Latin and North Germanic languages such as Swedish.
|V?num ? serv? port?tur.||Vinet bärs av tjänaren.||"The wine is carried by the waiter." (passive voice)|
|Servus v?num portat.||Tjänaren bär vinet.||"The waiter carries the wine." (active voice)|
Norwegian (Nynorsk) and Icelandic have a similar system, but the usage of the passive is more restricted. The passive forms in Nynorsk are restricted to only be accompanied by an auxiliary verb, which is not the case in Swedish and Danish.
In Latin, the agent of a passive sentence (if indicated) is expressed using a noun in the ablative case, in this case serv? (the ablative of servus). Different languages use different methods for expressing the agent in passive clauses. In Swedish, the agent can be expressed by means of a prepositional phrase with the preposition av (equivalent here to the English "by").
English, like some other languages, uses a periphrastic passive. Rather than conjugating directly for voice, English uses the past participle form of the verb plus an auxiliary verb, either be or get (called linking verbs in traditional grammar), to indicate passive voice.
If the agent is mentioned, it usually appears in a prepositional phrase introduced by the preposition by.
The subject of the passive voice usually corresponds to the direct object of the corresponding active-voice formulation (as in the above examples), but English also allows passive constructions in which the subject corresponds to an indirect object or preposition complement:
In sentences of the second type, a stranded preposition is left. This is called the prepositional passive or pseudo-passive (although the latter term can also be used with other meanings).
The active voice is the dominant voice used in English. Many commentators, notably George Orwell in his essay "Politics and the English Language" and Strunk & White in The Elements of Style, have urged minimizing use of the passive voice, but this is almost always based on these commentators' misunderstanding of what the passive voice is. Contrary to common critiques, the passive voice has important uses, with virtually all writers using the passive voice (including Orwell and Strunk & White).  There is general agreement that the passive voice is useful for emphasis, or when the receiver of the action is more important than the actor.
Merriam-Webster's Dictionary of English Usage refers to three statistical studies of passive versus active sentences in various periodicals, stating: "the highest incidence of passive constructions was 13 percent. Orwell runs to a little over 20 percent in "Politics and the English Language". Clearly he found the construction useful in spite of his advice to avoid it as much as possible".
In the field of linguistics, the term passive is applied to a wide range of grammatical structures. Linguists therefore find it difficult to define the term in a way that makes sense across all human languages. The canonical passive in European languages has the following properties:
The problem arises with non-European languages. Many constructions in these languages share at least one property with the canonical European passive, but not all. While it seems justified to call these constructions passive when comparing them to European languages' passive constructions, as a whole the passives of the world's languages do not share a single common feature.
Dixon acknowledges that this excludes some constructions labeled as passive by some linguists.
In some languages, including several Southeast Asian languages, the passive voice is sometimes used to indicate that an action or event was unpleasant or undesirable. This so-called adversative passive works like the ordinary passive voice in terms of syntactic structure—that is, a theme or instrument acts as subject. In addition, the construction indicates adversative affect, suggesting that someone was negatively affected.
In Japanese, for example, the adversative passive (also called indirect passive) indicates adversative affect. The indirect or adversative passive has the same form as the direct passive. Unlike the direct passive, the indirect passive may be used with intransitive verbs.
Hanako-ga tonari-no gakusei-ni piano-o asa-made hika-re-ta.
Hanako-NOM neighbor-GEN student-DAT piano-ACC morning-until played-PASS-PFV
"Hanako was adversely affected by the neighboring student playing the piano until morning."
Yup'ik, from the Eskimo-Aleut family, has two different suffixes that can indicate passive, -cir- and -ma-. The morpheme -cir- has an adversative meaning. If an agent is included in a passive sentence with the -cir passive, the noun is usually in the allative (oblique) case.
"That beautiful piece of dry fish got moldy."
In some languages, for example English, there is often a similarity between clauses expressing an action or event in the passive voice and clauses expressing a state. For example, the string of words "The dog is fed" can have the following two different meanings:
The additions in parentheses "force" the same string of words to clearly show only one of their two possible grammatical functions and the related meaning. In the first sentence, the combination of the auxiliary verb "is" and the past participle "fed" is a regular example of the construction of the passive voice in English. In the second sentence, "is" can however be interpreted as an ordinary copula and the past participle as an adjective.
Sentences of the second type are called false passives by some linguists, who feel that such sentences are simply confused with the passive voice due to their outward similarity. Other linguists consider the second type to be a different kind of passive - a stative passive (rarely called statal, static, or resultative passive), in contrast to the dynamic or eventive passive illustrated by the first sentence. Some languages express or can express these different meanings using different constructions.
The difference between dynamic and stative passives is more evident in languages such as German that use different words or constructions for the two. In German, the auxiliary verb "sein" marks static passive (German: Zustandspassiv, rarely statisches Passiv, in referring to German also called sein-Passiv or Sein-Passiv), while "werden" marks the dynamic passive (Vorgangspassiv or Handlungspassiv, rarely dynamisches Passiv, in referring to German also called werden-Passiv or Werden-Passiv or simply Passiv or Passivum). The English string of words "the lawn is mown" has two possible meanings corresponding to the example "the dog is fed" above. It can be used in the following two different senses:
German uses two different grammatical constructions for these sentences:
Further examples and explanations:
A number of German verbs such as bedecken ("cover"), erfüllen ("fill"), and trennen ("separate"), when used as stative verbs, usually only form static passives.
In English, the passive voice expressed with the auxiliary verb "get" rather than "be" ("get-passive") expresses a dynamic rather than a static meaning. But when the auxiliary verb "be" is used, the main verb can have either a dynamic or static meaning as shown below (including copies of some examples from above):
Verbs that typically express static meaning can show dynamic meaning when used in the passive formed with get, for example be known (static) vs. get known (dynamic):
All good writers use the passive voice.
There is general agreement that the passive is useful when the receiver of the action is more important than the doer[...] The passive is also useful when the doer is unknown, unimportant, or perhaps too obvious to be worth mentioning.