What's the difference?
Active voice is the default voice for academic writing–for all writing–because it is shorter, clearer and easier to read. It takes our brains less time to process than passive voice. It lightens up sentences and reduces the burden on the reader.
In the active voice, the subject does the action of the verb.
In the passive voice, the subject receives the action of the verb. The passive voice is essentially the active voice backwards.
Active: We found 3 instances of X. (past simple)
Passive: Three instances of X were found.
Active: We find 3 instances of X every time we look. (present simple)
Passive: Three instances of X are found every time we look.
Active: We have found 3 instances of X. (present perfect)
Passive: Three instances of X have been found.
If you start by writing almost entirely in active voice, you will have an easier time revising because your sentences will be more straightforward to begin with. When you choose passive voice, make it a conscious choice: make sure you have a good reason.
Is the subject unknown or unimportant? If I remove it, will the sentence still be clear?
Does passive voice allow me to use parallelism here?
Does passive voice allow me to place given information in the topic position?
Does passive voice allow me to remove a zombie noun and put the action in a verb form?
Passive voice is a tool that should be used wisely and carefully. You should be able to name your reason for using passive voice each time you use it–if you can't, you need to revise.
Reasons to choose passive voice
I need to put a particular bit of information in the beginning of the sentence to apply the given to new information principle. That structure requires a passive voice verb.
I don't know who did this and/or who did this is irrelevant. I can leave this information out and my reader will not be confused.
My sentence structure is otherwise perfect and I just changed a zombie noun into a verb, but to keep the same sentence structure, I need to use a passive voice verb.
If you don't have a reason, then you need to look at whether active voice might fit the sentence better.
How do you change the passive voice into the active voice?
The passive voice is made with the verb "to be" and the past participle of the main verb:
- was assessed
- is evaluated
- is being realized
- has been done
- had been written
First, identify the main verb, which is italicized above. Then, decide who is doing the action of that verb and make a new sentence starting with the actor.
The immunopathogenesis and clinical manifestations of this disease
We only partly understand the immunopathogenesis and clinical manifestations of this disease.
Several analytical lenses for examining policy surprises
We developed several analytical lenses for examining policy surprises.
Both of the original sentences above had new information in the topic position and the verb at the end. The revised sentences have everything where it should be:
- given information in the topic position,
- the verb close to the subject, and
- new information in the stress position.
After analyzing the samples, the plants
After analyzing the samples, we measured the plants daily.
We analyzed the samples, then measured the plants daily.
To investigate the source of nutrients, eggshell membranes
To investigate the source of nutrients, we compared the eggshell membranes.
These last two examples both have an introductory phrase in italics. The passive voice sentences are not grammatically correct because the verb in the introductory phrase does not go with the subject of the main sentence:
Did the plants analyze the samples?
Did the eggshell membranes investigate the source of nutrients?
Why does this work?
Our brains process the passive voice more slowly than the active voice. If we aim to write clearly, then we need to choose structures that place the smallest burden on the reader so that they can focus on the content. We don't want readers to waste any energy trying to decipher an unnecessarily heavy structure.
How important is it?
On a scale of 1-10, it's a 7: important. Using the active and passive voice appropriately can improve the flow of your text. Knowing how to go back and forth between them will help you apply the other techniques more effectively.
Are you having trouble writing in the active voice or knowing when the passive voice is appropriate? Ask for help!