In grammar, voice is the relationship between the action or state expressed by a verb, and its arguments (subject, object, etc.).
When the subject is the agent or actor of the verb, the verb is said to be in the active voice. When the subject is patient, target or undergoer of the action, it is said to be in the passive voice. For example, "The cat ate the mouse" is active, but "The mouse was eaten by the cat" is passive.
In a passive voice sentence, the subject and the direct object switch places. The direct object is promoted to subject, and the subject is demoted to a complement (that may be left out).
In English, the passive voice is a periphrastic construction, i.e. it is modelled using an ad hoc phrase structure with a different word order, an auxiliary verb and a participle of the main verb. In other languages, such as Latin, the passive voice is simply marked on the verb as an inflection.
Some languages (e.g. Sanskrit and Classical Greek) have a "middle voice". An intransitive verb that appears active but expresses a passive action characterizes the English middle voice. For example, in "The casserole cooked in the oven", "cooked" is syntactically active but semantically passive, putting it in the middle voice.
Many deponent verbs in Latin are also survivals of the Indo-European middle voice; many of these in turn survive as obligatory pseudo-reflexive verbs in the Romance languages such as French and Spanish.
Some languages have even more grammatical voices. For example, in Classic Mongolian there are five voices: active, passive, causative, reciprocal and cooperative.
Ergative languages usually do not have a passive voice, since their syntactic structure does not agree with it; instead some have an antipassive voice that deletes the object of transitive verbs.
Topic-prominent languages like Mandarin and Japanese tend not to have a passive voice, or to use it only in very special cases.
Dynamic and static passive
In some languages there is a distinction between static passive voice and dynamic passive voice, for example German. Static means, that an action was done to the subject at a certain point in time, whereas dynamic means that an action is done.
- "Ich bin am 20. August geboren" (German, literally "I am born on August 20")
- this is static, you have the state born on August 20
- "Ich wurde am 20. August geboren" (German, literally "I became born on August 20")
- this is dynamic, you were getting the state born on August 20
Usage of the English passive voice
In English, the passive voice is formed by combining the past participle of a verb together with one of the auxiliary verbs is or has. For example, consider the two sentences, "John is helped," and "John was helped." In both of them, the subject is John. The action is expressed by either "is helped" or "was helped". In both of those phrases, "helped," the past participle of "to help," describes the action. The inflection of "to be" expresses when the action occurrs.
Ditransitive verbs in English (i.e. with a subject, direct object and indirect object) can have a passive form which takes a direct object. Contrast:
- I sent a present to you or I sent you a present
- A present was sent (to you by me)
- You were sent a present (by me)
Very many English educators and usage guides, especially in the USA, consider it to be bad practice to use the passive voice because it obscures the subject. However, it is still common to use the passive voice in formal and business communications. It is particularly useful when creating deliberate vagueness or avoiding assigning blame. For example, "He was hurt," instead of "Someone hurt him." Also, sometimes the passive voice is preferable because a writer wishes to place or maintain emphasis on the object of the action, not for purposes of "deception," but simply as a matter of style. In such cases, the subject may also be obvious, or explicitly supplied with a "by X" construction later on.
The passive voice is also often found in academic and journalistic writings. In law as well as in science writing, the passive voice is the norm rather than a sign of deception.