Past tense and active voice

By Geoff Hart

Previously published as: Hart, G. 2019. Past tense and active voice. <https://www.worldts.com/english-writing/eigo-ronbun65/index.html>

One of the confusing aspects of English results from the similarity of two different but related aspects of English grammar: the tense of the verb (i.e., whether the action you’re describing is complete, is occurring right now, or will occur in the future) and passive voice. In this article, I’ll explain the difference and provide some advice on how to use these two aspects of English grammar in your writing.

The confusion most often arises from actions that are already finished, which is the case for most of the things you will describe in a journal manuscript. The simple past tense refers to actions that are finished. For most English verbs, this tense is created by changing the ending of the infinitive form of the verb (the form that begins with “to”, such as “to measure”) by adding -ed. For example, if the infinitive form of the verb is “to measure”, the simple past tense would be “measured”, as in the phrase “I measured the value of X.” This is called the “simple” past tense because only the form of the infinitive verb changes. There are many more complex forms of a verb.

To understand how this differs from passive voice, you first need to understand the concept of an actor. In grammatical terms, an actor is someone or some thing that acts (performs an action). In passive voice, the actor is not named, though its identity may be clear from context. Passive voice is usually created by adding the past tense of the verb “to be” (i.e., was or were) to the simple past tense of a verb without specifying who performed the action described by that verb. For example, “the project was completed before the scheduled date”. This example is both past tense (completed = in the past) and an example of “passive voice”. We don’t know who completed the project, and the phrasing encourages readers to ask who completed the action.

If we instead specify the actor, the result is called “active” voice, because actors (people who perform an action) are active. For example, “I completed the project before the scheduled completion date”. This clarifies that the writer, not some unnamed person or group, performed the action. Also note that the wording is simplified because the auxiliary verb “to be” (here, “was”) is eliminated.

For a long time, journals asked authors to use passive voice because they believed that this was more objective or because they believed that it was most important to emphasize the action, not the individual who performed it. The belief in the objectivity of this approach was never correct; neither the author nor the reader ever believed that scientists are always purely objective and have no opinions or biases. The belief that the emphasis should be on the action rather than the actor is easier to defend, but the result does not reflect how humans communicate. When you ask a colleague about the progress of their research, you’ll almost always hear a response similar to “we encountered a serious problem” or “we found something new and exciting”. You will almost never hear the passive forms of these phrases, “a serious problem was encountered” or “something new and exciting was found”. If we don’t speak that way, why would we want to write that way?

Active voice is more natural because it resembles speech more, and it is often both more concise and clearer. Active voice particularly increases the clarity when there may be two or more actors, which is common when you start by describing previous research and continue by describing something that occurred later, such as your own research. For example, “the previous research was based on PCR analysis, but the present research was based on CRISPR technology”. This is shorter (by about 20 characters) and clearer if we write “our previous research used PCR analysis, but the present research used CRISPR technology”.

Because of the improved clarity, concision, and ability to emulate how people really communicate, many journals, including prestigious journals such as Nature and Science, either require authors to use the active voice, or strongly recommend this voice. If a journal reviewer criticizes you for using active voice, it’s appropriate to remind them that if both Nature and Science endorse active voice, that should be a good enough reason for the reviewer to accept this style.

Journal reviewers sometimes ask us to eliminate active voice and write phrases such as “the molecular weight was measured” rather than “we measured the molecular weight”. Often, what they really mean is that they dislike seeing “I” or “we” repeated so often. If you can find other articles published by the journal that will review your paper and that use “I” and “we”, all you need to do is reply that this practice is accepted by the journal and cite examples of articles that use that approach. A compromise is to use passive voice only in the Methods section, and switch to active voice in the Results and Discussion (e.g., “we found that the molecular weight was 34 kDa”).

Note that although the argument I have presented here is logical, it may not convince a journal reviewer or journal editor. In that case, it’s wiser to simply accept the reviewer’s or editor’s requirement to use passive voice rather than risk rejection of your paper over such a small point.