Active and passive sentences

The passive voice occurs when the person or thing that performs an action is not the grammatical subject of the sentence. Instead, the person or thing that receives the action is placed before the verb. Passive sentences are formed using the verb to be combined with a past participle.

Active construction

The dog bites the bone.

Passive construction

The bone is bitten by the dog.

In a passive construction, the actor does not have to be named at all.

Passive construction

The bone is bitten.

Writers are often advised to avoid the passive voice, but it is not a grammatical error. In academic writing, this type of sentence structure is sometimes useful or necessary. However, overusing it can make your writing unclear or convoluted.

Avoiding the passive voice

In most cases, it’s best to use active sentence constructions where possible. Sometimes the passive voice makes a sentence less clear by obscuring the actor.

The decision was made to close the factory.

Who made the decision? To properly understand what occurred, we need to know who was behind the action. This is possible in the passive voice, but the sentence becomes convoluted.

The decision was made by the CEO to close the factory.

An active construction is preferable for clarity and concision.

The CEO made the decision to close the factory.

If you write a passive sentence, consider carefully whether leading with the actor would strengthen your point.

This is also relevant when discussing previous research: active constructions that specify who is responsible for findings can make your writing more credible and convincing.

  • Evidence has been found of nonhuman primates engaging in ritualistic behaviour.
  • Smith (2015) found evidence of nonhuman primates engaging in ritualistic behaviour.
  • Several recent studies have found evidence of nonhuman primates engaging in ritualistic behaviour.

Using the passive voice

Some types of academic writing do not permit the use of first-person pronouns. In these cases, the passive voice can be used for referring to your own actions.

Active voice with first-person pronounsPassive voice to avoid first-person pronouns
I gathered data through an online survey.Data was gathered through an online survey.
We recorded the measurements at 9am every day for three weeks.The measurements were recorded at 9am every day for three weeks.

If you use the passive voice in more complex sentences, make sure to avoid dangling modifiers.

The passive voice is often also appropriate when the subject of an action is unknown or unimportant to the meaning of the sentence.

Thirty votes were counted in favour of the amendment.

In this case, the object of the action – the votes – is more important than who did the counting. Specifying the actor wouldn’t add any useful information to the sentence.

More research is required to understand this phenomenon.

With verbs like require, there is often no particular actor who does the requiring, so the passive voice is used to state a general sense of necessity or obligation.

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Shona McCombes

Shona has a bachelor's and two master's degrees, so she's an expert at writing a great thesis. She has also worked as an editor and teacher, working with students at all different levels to improve their academic writing.

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