So far in this series, we've looked at two instances when it's actually better to use the passive voice than the active voice—when the doer is unimportant and when the action is more important than the doer. In this final installment, we're look at the last case where it's good to break the rule.
The Doer is Obvious
When it's obvious who performed the action—and they're not important to your sentence—use the passive voice. This keeps your sentences short and your readers' attention on the right stuff.
Squash is typically planted only in July and August.
Typically, farmers plant squash only in July and August.
Obviously, the doer is the farmer, but who cares? I'm more interested in what is planted when. This is particularly important in context. If you write a paragraph where the subject is squash and include the second sentence—whose subject is farmers—you've directed your readers' attention to an unimportant and obvious detail. Now your readers will have to redirect their attention to squash. (Note: Obviously, that's not a big deal for the subject of squash. But when you start writing on more complex matters, your readers will thank you for making it easy to stay on track!)
Other Examples of This:
I was born on a wintery night in January. (It's obvious that my mother gave birth to me, but again, is this about me or my mom?)
Music has been enjoyed for thousands of years. (People—or some variation of the idea—are the obvious doers, but this passive sentence keeps readers' attention on the subject I want them to pay attention to—music.)
Last summer, the forests around my house were burned almost to the point of extinction. (The doer is obvious—fire. But I want readers to focus on the forests, not the fire.)