Here are a few excerpts from from H. J. Tichy's book, Effective Writing for Engineers, Managers, Scientists (2nd Edition):
"Always use the passive voice" is a prescription so frequently pressed on writers of informational prose that it has proved to be one of the most harmful fallacies, if not the most harmful. Frequently enunciated by a person in a position superior to a writer's, the fallacy bears the heavy weight of law. This erroneous advice may confront an engineer or scientist first in graduate school. There professors may insist that students write as the professors do, in the passive voice, in order to appear scholarly, to show objectivity, to acquire a style like that of journal articles, or -- more brutally -- to make papers acceptable. in business and industry some supervisors have discovered the use of the passive to evade responsibility and therefore use it as ruthlessly as politicians do.
. . .
The prevalence of the passive voice in government and industry and in science and technology amazes those who meet it for the first time. They find the following experience unnerving. A director of training asked a consultant to confer with a foreign-born engineer who had learned English while working for two years in the United States. When the consultant met the engineer, she apologized for her lateness.
"It is nothing," he replied courteously. "A cigarette was smoked and a book was read while waiting."
He was learning engineering English fast -- not only the passive voice but the incorrect ellipsis that often accompanies it.
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The passive voice weakens style when it is used, consciously and unconsciously, to evade responsibility. A popular passive construction is "It is thought that ....' used anywhere but in science or technology, this indicates that a general opinion or truth follows. But when writers on business, science, or technology use it, they may mean, "I think that ...," "we think that ...," "the Committee thinks that ..," or even "I hope that somebody reading this report thinks that ...." By close attention some readers may learn to interpret "it is thought that." Readers of a committee report may mentally substitute, "The committee thinks that." But after the readers have interpreted two paragraphs successfully this way, they come to "it is thought that" followed by a common misconception, which is corrected in the next sentence. Do the writers mean that the committee held that misconception? Indeed, no. Now they are using "it is thought that" to introduce a general opinion that they wish to correct.
Readers of minutes written in the evasive passive often find themselves sounding like hoot owls as they scream, "Who? Who? Whooooo?" ...
Another harmful fallacy about style is the rule "Avoid all personal pronouns. Never use I or we." ... An attempt to achieve objectivity by avoiding personal pronouns is a mistake, and the idea that using the third person instead of the first person achieves modesty is equally wrong. Discarding necessary common words like I and we merely leads to awkward writing marked by excessive use of the passive and by reliance on weak indirect constructions. Writers deprived of I and we turn to unnatural and objectionable substitutes like the author, one, the present writer, this reporter, your correspondent, and the undersigned or even to titles -- the vice president, the chairman ...
Some writers consider we less personal than I. In imitation of an editorial writer, who is expressing the opinions of a board, a writer may mistakenly use the plural we. ... the substitution of we for I can cause dangerous or embarrassing confusion. When writers using company stationery state, "we will do," they obligate their company unless in the first sentence in which we appears they clearly define the we to mean something else. The possible embarrassment is illustrated well by an experience of the Reverend John A. O'Brien when he proposed a conference on population growth. The last paragraph of a newspaper account states: "Although Father O'Brien used the phrase `we propose' in connection with his proposals, a spokesman for Notre Dame said the professor was speaking for himself." Writers who use we should be sure that they have authority to speak for others. And the only safe authorization is written.
Most scientific and technological journals now permit authors to use I for a single writer and we for more than one writer, especially when the material is personal, as in interpretation of results and in predictions. Indeed, many editors urge this use wherever appropriate. The American National Standard for the Preparation of Scientific Papers for Written or Oral Presentation, which includes an impressive listing of the many organizations represented in its views, states "When a verb concerns action by the author, the first person should be used, especially in matters of experimental design (`to eliminate this possibility, I did the following experiment')." It then warns against "constant use" of the first person, a warning that teachers of freshman composition present so frequently that few students who pass a good course should have trouble. Obviously, however, avoiding for years the use of pronouns in the first person necessitates some adjustment when writers begin to use them in scholarly or business writing. It is well to bear in mind the following aids to good use: