Passive voice in scientific writing: angel or devil?

For years, we were told that in scientific writing we needed to use passive voice to sound formal, neutral and serious. More recently, the contrary philosophy bursted in: suddenly, passive voice had to be by all means avoided as it forces hiding the agent of the sentence and creates confusion. This paradigm shift left many of us in the doubt… is using passive voice in formal, scientific writing right or wrong?

The answer is, as usual, it depends. Passive voice can be a very powerful writing tool, but using it for the wrong reasons may lead to confused, suspicious readers. Take the following example:

The simulations were performed at sea level to be relevant to the calibration. A nominal composition was chosen for the computations. A small portion of gases was included in the initial composition. A completely homogeneous mixture was assumed.

For the reader, there is no agent in sight here and it is (oh so) difficult to picture a consequence without a cause. Who instigated the actions? Who moved forward the experiment? The authors, the technicians, a student, another lab…? The answers are obvious to the writer. He knows how the story developed, so he just explains the outcome. Academic writers do sometimes forget that they are the ones staging an event for the reader, and they need to make that clear in order to be effective.

Should we always write then in active voice?

After all, the active voice lets us better visualise actions, right? Let’s take a second example:

This lady doesn’t feel good. She is being driven too fast on this mountainous road.

This lady doesn’t feel good. The driver is going too fast on this mountainous road.

Both sentences work although they are fundamentally different: the first has a passive part and the second is all active. With the first, the reader’s attention is kept on the lady. With the second, the attention shifts from the lady to the driver. Steven Pinker in The Sense of Style tells us that the writer is like a cameraman directing the gaze of the reader towards what she should look at. In our example above, you first looked at the lady. With the passive voice you stayed there, whereas in the all active sentence you switched from one protagonist to another. What if the driver is the important one?

The driver sees the lady feeling not well. He drives too fast on this mountainous road.

Blindly banning passive is not the solution

It all depends on the object of your text, on who should be in the spotlight. Let’s take another example, this time from a scientific article:

The peak power decreased by 35%. It was shaved by innovative demand-side management.

The peak power decreased by 35%. The control unit applied innovative demand-side management.

Here again, in the first sentence, the passive voice enables us to stay focused on the main subject–the peak power. We can then continue the paragraph with more information on demand-side management and link it to the control unit if this is relevant.

A more elaborate rule

Instead of passively applying simplistic rules of thumb like “Do” or “Don’t use passive voice”, let’s formulate the theory differently:

  1. Do not use passive voice to hide who did what; to hide the “I”, the “we” or the authors of another publication.
  2. Use passive voice when the important part is the object, when you want your reader to keep looking at something while you connect your sentences together.

If we, as scientists, claim to push the boundaries of science, let’s be effective about it.

One Reply to “Passive voice in scientific writing: angel or devil?”

  1. I think this is a really good point ! Actually this problem bothered me a lot when writing papers. Sometimes, using passive voice makes a sentence difficult to understand, which makes the paper difficult to understand, and makes the readers hard to read it.
    Yes passive voice is good to emphasize the object. So when we need to emphasize the object we could use it.
    For many situations, a normal order sentence will make the paper more fluency.

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