Verbs are tricky things. At their most basic level, they describe actions, and what or whom those actions affect. The vast majority of sentences contain verbs and at least one noun (though often more than one)—usually the ‘doer’ and the ‘done to’—or to be more technical, the subject and the object. For example:
Mikey swept the floor.
In this example, Mikey is the subject—he’s the doer. The verb is swept, and the object is the floor—the done to. In this example, the verb is what’s known as active, because the subject of the verb is performing the verb.
But what’s going on in this example?
The floor was swept by Mikey.
The floor is now mentioned at the start of the sentence, and has become the subject of the sentence—however, it’s still the done to. The effect of this is that the floor has become more prominent in the sentence, and the person who swept it becomes less important. In fact, Mikey could be left out of the sentence entirely:
The floor was swept.
This is called the passive—where the ‘done to’ becomes more prominent in the sentence than the doer.
The passive voice is a powerful tool in writing—it enables you to emphasise different parts of a sentence to assist in describing an event. For instance, compare the following:
The television network has cancelled my favourite show!
My favourite show has been cancelled!
In this example, the most important information—that the show was cancelled and that it was the speaker’s favourite—is emphasised in the second sentence.
The passive voice is also a useful tool to use when the doer is unknown. For example:
My wallet was stolen.
However, using the passive voice can also obscure relevant facts. For instance:
Marie Curie discovered radium in 1898.
Radium was discovered in 1898.
The discoverer is an important aspect of this statement, and her identity is not acknowledged in the passive construction above. This can become an issue in academic writing. Sometimes, students feel that using the passive voice is a more formal way of expressing themselves, often to the detriment of their writing.
However, there are some exceptions. In scientific writing, researchers often employ the passive voice when describing an experiment. For example:
The effects were observed over a period of 10 days.
In the example, there is no need to say that the effects were observed by the researcher—this is implied by the structure of the paper itself. Additionally, this sentence if rendered as active would necessarily include ‘I’ or ‘we’ (i.e. We observed the effects over a period of 10 days), which is generally not encouraged in academic environments.
The aim of academic writing is always to express your arguments as succinctly as possible and with as much clarity as possible. Usually, this means employing the active voice to ensure that all the relevant information about the doer and the done to is included, but there are examples where passive voice is the generally accepted style. If in doubt, ask a lecturer, supervisor or professional editor for advice.