Use of passive voice in English
2 May 2016
(This is a modified version of my description of the use of passive voice in an answer at Quora)
The most important use of the passive voice in English is to de-emphasise (or omit) the agent of an action.
In the spoken language it's used where the agent is not important. Let's look at a few examples:
a) In the following sentence the agent is not important:
He was taken to hospital.
This tells us that someone took 'him' to hospital, probably an ambulance. We could have written:
The ambulance took him to hospital.
But in fact, it's not really important who took him to hospital. What is important is that something happened to the subject -- that 1) someone took him to the hospital and 2) it's highly likely that he couldn't go himself. That's why the passive is used. There's no real reason to specify in detail that it was an ambulance that took him, although it would normally be assumed that it was.
This usage places the focus on the patient or receiver of the action. In telling a story, the focus will normally be on the main character. If, for instance, the story involves a snake biting the person in question, it's normal to phrase this as:
He was bitten by a snake.
That is because the focus is not on the snake but on the person concerned.
These passives are often used for events that are outside the control of the patient or recipient of the action. A snake is an impersonal force and being bitten by one is an unfortunate accident. On the other hand, the passive is ordinarily not used in this situation:
His wife left him.
It is strange in English to say that "He was left by his wife" (although some people do use it!)
b) The passive may also be used when the agent is unknown. For example,
When I came out this morning, I found that the road had been dug up.
It may have been council workers or it may have been someone else who dug up the road. It's not really that important who dug it up. What is important is that something happened to the road. Interestingly, the sentence actually tends to suggest that the person or people digging up the road may have been entitled to do so. This can be seen by contrasting it with this sentence:
When I came out this morning, I found that someone had dug up the road.
In this sentence, the actual identity of the agent is not clear -- but this does not result in the use of the passive. Not at all. That is because the agent, even though unknown, is important. By using the subject "someone", the sentence puts the focus on the agent, suggesting that the speaker is angry or annoyed at this "someone" for digging up the road. That is why the sentence deliberately uses "someone" as the subject instead of using the passive voice, which would play down the identity of the agent.
c) There are cases where the passive has become the default mode and the active voice would be very strange:
He was born on 14 August 2005.
Although this is grammatically a passive, most people probably don't feel it to be so. "He was born on xxx date" is a fixed expression and in this sense differs somewhat from the normal use of a passive. In fact, the agent "bearing" him is his mother, but it would be very, very uncommon (although not completely impossible) to say:
His mother bore him on 14 August 2005.
d) There are some special uses of the passive that logically seem awkward but are quite natural in English. One is this sentence:
He was killed in an accident.
Here there is no agent; this is simply a turn of phrase in English and means "He died in an accident". This can also be used for other kinds of violent incident: a war, a battle, an attack, a raid, a fire, a rush, etc.
He was killed in the war.
Forty soldiers were killed in the battle.
Two people were killed in the fire.
As the crowd panicked and tried to leave the stadium, ten people were killed in the rush.
Note again that there is no real agent in these sentences. The soldiers killed in battle weren't necessarily killed by the enemy; they could also have been killed by 'friendly fire'. The people killed in the rush to leave the stadium weren't killed by any single person but by the crowd as a whole.
This kind of expression can't be used for quieter scenarios. For example, with regard to childbirth, the correct expression is "She died in childbirth".
e) Sometimes the "agent" of the passive is something quite abstract, for instance, a situation. For example:
He was left holding the baby.
This isn't necessarily the result of an action by a particular agent or agents. It simply describes the result of a set of circumstances. This is even more apparent in sentences like:
I was left with no alternative.
In this sentence, that which left the speaker no alternative was the entire situation, not necessarily any single human agent.
In the written language, the passive is a widely used device for avoiding mention of the writer. The motive behind this particular usage is a long-standing prohibition in formal English prose on writing from a personal point of view. Stylistically it was felt to be inappropriate to mention the writer in formal prose (although it was acceptable to write novels in the first person).
a) This is seen in writing up scientific experiments, where the passive is obligatory:
The sample was placed in a beaker and heated for 30 seconds using a Bunsen burner.
In a sentence like this, it would be stylistically inappropriate to specify the agent as in:
I placed the sample in a beaker and heated it for 30 seconds using a Bunsen burner.
My lab assistant placed the sample in a beaker and heated it for 30 seconds using a Bunsen burner.
The agent of the action is irrelevant to the experiment, which must be described objectively.
b) Other kinds of reporting also use the passive voice -- for instance, police reports:
The suspect was handcuffed, escorted to the police station, and intensively interrogated about his movements on the day in question.
The use of passive voice in this kind of prose sounds impersonal and authoritative. The focus is totally taken away from the actions of the agent and placed on what happened to the suspect. This kind of prose is highly "depersonalised".
The widespread use of the passive is a result of a strong feeling among English speakers that passive voice is appropriate to this kind of prose style, making it sound more "authoritative", "impersonal" and "impressive". This has led people to overuse it, to the extent that it has become a bad habit. Too many people would rather write:
Steps were taken to increase budget allocations with a view to ameliorating shortages of personnel and resources in primary care.
The government increased the budget for primary care with a view to ameliorating shortages of personnel and resources.
This has led to a reaction against the overuse of passive voice in writing. Style guides generally recommend against it because it's felt to detract from immediacy and directness, leading to a wooden style. What is worse, because it goes out of its way to hide the agent of the sentence, the passive voice is perceived as an evasion of responsibility, especially in the impersonal language of bureaucratic prose.
While such recommendations have led to something of a campaign against passive voice, it's incorrect to jump to the conclusion that the passive is "bad". As we have seen above, the passive voice has its legitimate uses. What should be discouraged is the unthinking use of passive voice in contexts where it isn't really needed.
Finally, to demonstrate the importance of the passive voice in English, we can find another "hidden" use of the passive in participial clauses like the following:
Combined with the effects of prolonged malnutrition and inadequate shelter, diseases such as influenza and pneumonia brought about the deaths of thousands of people in the wake of the war.
This is effectively a "reduced passive". The meaning is:
When they were combined with the effects of prolonged malnutrition and inadequate shelter, diseases such as influenza and pneumonia brought about the deaths of thousands of people in the wake of the war.
While not a full passive, this kind of participial clause is an abbreviation of the passive voice and is entirely passive in meaning. You will notice that this expression also hides the agent of the action. It is not important who (if anyone) combines "diseases such as influenza and pneumonia" with "the effects of prolonged malnutrition and inadequate shelter". What is important is that these two factors were combined together. This kind of construction is very common in English prose.
For useful information about using the passive voice, refer to the following: 1. Passive Voice, 2. Passive Voice: When to Use It and When to Avoid It, 3. WHY use the passive voice in academic writing?