In grammar, the voice (also called diathesis) of a verb describes the relationship between the action (or state) that the verb expresses and the participants identified by its arguments (subject, object, etc.). When the subject is the agent or doer of the action, the verb is in the active voice. When the subject is the patient, target or undergoer of the action, the verb is said to be in the passive voice.
For example, in the sentence:
- The cat ate the mouse.
The verb "ate" is in the active voice, but in the sentence:
- The mouse was eaten by the cat.
The verbal phrase "was eaten" is passive.
- The hunter killed the bear.
The verb "killed" is in the active voice, and the doer of the action is the "hunter". To make this passive:
- The bear was killed by the hunter.
The verbal phrase "was killed" is followed by the word "by" and then by the doer "hunter".
In a transformation from an active-voice clause to an equivalent passive-voice construction, the subject and the direct object switch grammatical roles. The direct object gets promoted to subject, and the subject demoted to an (optional) complement. In the examples above, the mouse serves as the direct object in the active-voice version, but becomes the subject in the passive version. The subject of the active-voice version, the cat, becomes part of a prepositional phrase in the passive version of the sentence, and could be left out entirely.
The passive voice is employed in a clause whose subject expresses the theme or patient of the verb. That is, it undergoes an action or has its state changed.
In the passive voice the grammatical subject of the verb is the recipient (not the doer) of the action denoted by the verb.
The Spanish language and the English language use a periphrastic passive voice; that is, it is not a single word form, but rather a construction making use of other word forms. Specifically, it is made up of a form of the auxiliary verb to be and a past participle of the main verb. In other languages, such as Latin, the passive voice is simply marked on the verb by inflection: librum legit "He reads the book"; liber legitur "The book is read".
Some languages (such as Albanian, Bengali, Fula, Tamil, Sanskrit, Icelandic, Swedish and Ancient Greek) have a middle voice. This is a set of inflections or constructions which is to some extent different from both the active and passive voices. The middle voice is said to be in the middle between the active and the passive voices because the subject often cannot be categorized as either agent or patient but may have elements of both. For example it may express what would be an intransitive verb in English. For example, inThe casserole cooked in the oven, cooked is syntactically active but semantically passive. In Classical Greek, the middle voice often has a reflexive sense: the subject acts on or for itself, such as "The boy washes himself", or "The boy washes". It can be transitive or intransitive. It can occasionally be used in a causative sense, such as "The father causes his son to be set free", or "The father ransoms his son".
In English there is no longer a verb form for the middle voice, though some uses may be classified as middle voice, often resolved via a reflexive pronoun, as in "Fred shaved", which may be expanded to "Fred shaved himself" – contrast with active "Fred shaved John" or passive "John was shaved by Fred". This need not be reflexive, as in "my clothes soaked in detergent overnight". English used to have a distinct form, called the passival, which was displaced over the early 19th century by the passive progressive (progressive passive), and is no longer used in English. In the passival, one would say "the house is building", which is today instead "the house is being built"; likewise "the meal is eating", which is now "the meal is being eaten". Note that the similar "Fred is shaving" and "the clothes are soaking" remain grammatical. It is suggested that the progressive passive was popularized by the Romantic poets, and is connected with Bristol usage.
Topic-prominent languages like Mandarin tend not to employ the passive voice as frequently. Mandarin-speakers construct the passive voice by using the coverb 被 (bèi) and rearranging the usual word order. For example, this sentence using active voice:
Note: the first line is in Traditional Chinese while the second is Simplified Chinese.
狗 咬了 這個 男人。 狗 咬了 这个 男人。 Gǒu yǎo-le zhège nánrén. dog bite-PERFECT this man "A dog has bitten this man."
corresponds to the following sentence using passive voice. Note that the agent phrase is optional.
這個 男人 被 (狗) 咬了。 这个 男人 被 (狗) 咬了。 Zhège nánrén bèi (gǒu) yǎo-le. This man BEI dog bite-PERFECT. "This man was bitten (by a dog)."
In addition, through the addition of the auxiliary verb "to be" (shì) the passive voice is frequently used to emphasise the identity of the actor. This example places emphasis on thedog, presumably as opposed to some other animal:
這個 男人 是 被 狗 咬了。 这个 男人 是 被 狗 咬了。 Zhège nánrén shì bèi gǒu yǎo-le. This man to be BEI dog bite-PERFECT. "This man was bitten by a dog."
Although a topic-prominent language, Japanese employs the passive voice quite frequently, and has two types of passive voice, one that corresponds to that in English and an indirect passive not found in English. This indirect passive is used when something undesirable happens to the speaker.
彼 は 泥棒 に 財布 を 盗まれた。 Kare wa dorobō ni saifu o nusumareta. He TOPIC thief AGENT wallet OBJECT steal-PASSIVE-PAST "His wallet was stolen by a thief." 僕 は 彼女 に 嘘 を つかれた。 Boku wa kanojo ni uso o tsukareta. I TOPIC her AGENT lie OBJECT tell-PASSIVE-PAST. "I was lied to by her." (or "She lied to me.")