Conventional views of writing prefer active voice to passive voice; however, writers must seek to craft sentences with purpose, meaning that sophisticated writing will include both active and passive voice. Active voice sentences include subject/verb constructions that place the subject doing the action of the verb before that verb. Passive voice includes sentences that either omit the subject doing the action of the verb or place the subject doing the action after the verb; in both cases, the verb is a “to be” + verb construction. [EDIT]
Conventional and traditional views of academic and scholarly writing dictate that writers should avoid passive verb constructions. For a basic understanding, consider the following:
1) The ball was kicked by the girl.
2) The ball was kicked.
3) The girl kicked the ball.
The first example is a passive verb since “ball” sits in the subject position, but is receiving the action of the verb (thus, passive).
The second example is also passive, but this example demonstrates a serious complaint about passive sentences: The agent doing the action is absent. Many who manipulate the language resort to passive sentences such as the second example in order to evade responsibility; a memorable moment in history has been ascribed to Oliver North during the Iran-Contra hearings: “Documents were shredded.”
The third example is active, and the preferred verb construction for academic and scholarly writing. Writers, however, do often draft passive sentences, but as with other grammatical and stylistic guidelines, the key is purpose. A purposeful passive sentence (although not intended to deceive) is far different than a careless writer who falls into persistent passive voice but is unaware of the construction.
For on-line help with passive and active voice, visit:
http://owl.english.purdue.edu/owl/resource/601/02/
