What is the Passive Voice?
Put simply, a passive grammatical construction is one in which the subject has something done to it by the object. Where in the sentence "Jane eats an apple," the subject (Jane) does something to (eats) the object (an apple), in the sentence "An apple is eaten by Jane," the subject (an apple) has something done to it by (is eaten by) the object (Jane). "Jane eats an apple" is active, where "An apple is eaten by Jane" is passive.
As with an active construction, a passive construction doesn't always need an object. "Harry was hit" is passive; because it lacks an object, the sentence doesn't identify the agent (the thing or person doing the hitting).
Should You Use Passive Constructions in Writing?
Critics of the passive voice have suggested all sorts of reasons why the passive is bad. Active voice, we're told, is immediate and engaging for readers, while the passive voice is weak and lacking in precision. These statements, however, fall short as blanket rules for good writing. In many cases, the passive is more engaging and sounds more natural, and the active may sound very odd. For example, take these (made-up) headlines:
Springfield Man Killed in CollisionCollision Kills Springfield Man
Which has more impact? Which sounds more natural? Certainly the first, which is a passive construction. Try this:
President Kennedy Assassinated in Dallas, TexasOswald Assassinates President Kennedy in Dallas, Texas
Again, the first is passive and gets straight to the point. The second, in the active voice, confuses the reader from the start with an unfamiliar subject: Who is Oswald? Why is he so important? But at this stage in the game (imagining we're back in 1963), he's not important. The fact the headline wants to convey is that the President has been shot, not that a particular person is the culprit.
The linguist Geoffrey K Pullum, a brilliant and occasionally ferocious grammarian, provides this example:
For me to report that I paid my bill by saying "The bill was paid by me," with no stress on "me," would sound inane. ... But that is no argument against passives generally. "The bill was paid by an anonymous benefactor" sounds perfectly natural.How to Know When to Use the Passive Voice
A good writer uses her ear rather than relying on grammatical prescriptions often invented with little regard for context. If in doubt, write it both ways -- active and passive -- and read them aloud. Go with what sounds natural, succinct and clear. The best construction is usually obvious.