English Passive Voice - Reasons For Using The Passive Voice

Reasons For Using The Passive Voice

The passive voice can be used without referring to the agent of an action; it may therefore be used when the agent is unknown or unimportant, or the speaker does not wish to mention the agent.

• Three stores were robbed last night. (the identity of the agent may be unknown)
• A new cancer drug has been discovered. (the identity of the agent may be unimportant in the context)
• Mistakes have been made on this project. (the speaker may not wish to identify the agent)

The last sentence illustrates a frequently criticized use of the passive – the evasion of responsibility by failure to mention the agent (which may even be the speaker himself).

Agentless passives are common in scientific writing, where the agent may be irrelevant:

• The mixture was heated to 300°C.

However the passive voice can also be used together with a mention of the agent, using a by-phrase. In this case the reason for use of the passive is often connected with the positioning of this phrase at the end of the clause (unlike in the active voice, where the agent, as subject, normally precedes the verb). Here, in contrast to the examples above, passive constructions may in fact serve to place emphasis on the agent, since it is natural for information being emphasized to come at the end:

• Don't you see? The patient was murdered by his own doctor!

In more technical terms, such uses can be expected in sentences where the agent is the focus (comment, rheme), while the patient (the undergoer of the action) is the topic or theme (see Topic–comment). There is a tendency for sentences to be formulated so as to place the focus at the end, and this can motivate the choice of active or passive voice:

• My taxi hit an old lady. (the taxi is the topic, the lady is the focus)
• My mother was hit by a taxi. (the mother is the topic, the taxi is the focus)

Similarly, the passive may be used because the noun phrase denoting the agent is a long one (containing many modifiers), since it is convenient to place such phrases at the end of a clause:

• The breakthrough was achieved by Burlingame and Evans, two researchers in the university's genetic engineering lab.