Perhaps you received a graded paper with instructions not to use the passive voice, and are not entirely sure what that means. Oftentimes, professors – especially those in the humanities – prefer that students use the active voice almost exclusively to the passive.
In short, active and passive voice have to do with the relationship between subject, action, and object in a sentence. Both ways, the meaning of the sentence remains essentially the same, but the difference in emphasis can lead to slightly different interpretations.
Subject, Action, Object
Although some might find this surprising, many students do not understand the fundamental rules of sentence construction. Every sentence must have at minimum a subject and an action.
For example, one of the shortest verses in The Bible, “Jesus wept” (John 11:35), is a complete sentence because it contains a subject (Jesus) and an action (wept). Furthermore, this sentence has an unstated object. What did Jesus weep? Tears. Tears are the object that Jesus wept.
In active voice, we find a direct progression between subject, action, and object, whereas in the passive voice we flip the order around. Thus, the previous example employs active voice:
Jesus (subject) wept (action) tears (object).
To employ passive voice, we reverse the order, turning the object into the subject and vice versa:
Tears (subject) were wept (action) by Jesus (object).
Note the additions made when converting to passive voice: a helping verb, “were,” and the preposition, “by.” These are the telltale signs that you are dealing with passive voice.
Be careful, though, as students often make the mistake of associating any use of a helping very with passive voice, but sometimes the helping verb needs to be there to establish tense.
For example, “Jesus has wept” is not an example of passive voice, nor is “Jesus is weeping” as the helping verbs in both merely indicate when the action occurred. Generally, look for the word “by” to establish the passive voice, although this word is sometimes only implied, as in the passive construction, “Tears were wept.”
Why does it Matter?
The preference for active voice is largely stylistic – fewer words are used and the progression from subject directly to object leads to clearer meaning. This preference is strongest in the humanities and social sciences – particularly in the field of business – in which human subjects take priority over non-human objects.
However, the passive voice is less of a problem in fields such as engineering where a person might be of less importance than the process or technology that person is using.
Finally, you may occasionally want to use the passive voice to downplay emphasis or responsibility, especially if you leave the object implied. For example, compare the difference between “I lost your money,” and the “The money was lost.”
Moreover, it behooves you to pay attention to how others construct their sentences using the passive or active voice, to see where they might try to deny or deflect responsibility.