The terms active and passive voice refer to a style of writing that reflects how subjects and verbs are used in sentences. The active voice is generally considered the best grammatical structure to use between the two, with authors often told to avoid using the passive voice altogether. However, it is a common myth that the passive voice is always wrong. In scientific writing, both voices are necessary to write clearly. Different situations in a paper will require the appropriate use of each, meaning the active vs passive voice debate should instead be addressed in a practical, balanced way.

In this article, we will explain the difference between active and passive voice, the grammatical order of each voice and how this alters sentence structure, and the best approach for using both voices in scientific writing.

What is the active voice?

The active voice in English is a grammatical structure that follows the standard sentence structure: subject-verb-object. This order places emphasis on the ‘doer’ of the action, rather than the object.

• We weighed the tree bark.

Here, the ‘doer’ (the plural noun ‘we’, referring to the authors of the study) is placed before the verb (‘weighed’), giving emphasis to the subject performing the action on the object (‘tree bark’).

The active voice often makes writing clearer, more direct, and dynamic, hence the general advice given to authors to use the active over passive voice.

What is the passive voice?

In contrast, the passive voice reverses the standard sentence structure of the active voice. Instead of the subject-verb-object order, the passive voice shifts focus to the object receiving the action.

• The tree bark was weighed (by the group).

Here, the sentence structure is: object- verb (conjugated)-past participle-‘by’-subject.

Active vs passive voice: when to use each in scientific writing

Generally, authors may write using either the active or passive voice. However, the active voice is usually encouraged over the passive voice in scientific writing. The extent to which the active voice is favoured may further depend on the stylistic guides of individual journals.

Despite the general privileging of the active voice in scientific writing, there are instances when the passive voice is needed for clarity.

Examples of when to use passive voice in a paper

1. To emphasise the object being acted upon.

• The onset risk of Type 2 diabetes is increased by diet.

2. When the subject is unknown or irrelevant. For example, in the Methods section of a paper, we already know the scientists or authors performed the procedures. Therefore, passive voice is acceptable.

• Test tubes were filled with 20 ml of solution and stored at -5ºC.

3. To keep the subject and focus of the passage clear.

• Chronic fatigue syndrome can lead to sleep problems. The exact cause of chronic disease syndrome is unknown; instead, it is believed to be a complex, multi-factor condition.

Authors may also be advised to use passive voice to create a formal or neutral tone. However, this advice is best understood in the context of which section of the paper you are writing. For example, passive voice can be used effectively in the Methods section due to its objective angle, while the Introduction, Results, and Conclusion sections benefit from a more direct, concise, and persuasive style achieved by the active voice.

Because scientific writing requires the use of each voice where appropriate, the active vs passive voice debate lingers. While both grammatical structures are suitable for scientific writing, it is not always clear for authors which voice they should be using and when. As a general rule, authors should prioritise stylistic consistency, conciseness, and clarity if in doubt.

Further English support for authors

Beyond grammatical structures such as the active and passive voices, English grammar can cause lots of confusion for authors, especially for those writing in English as a second language. Check out our grammar terms glossary for authors to ensure you are familiar with terms and functions.

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