Learn English – Active vs Passive voice in lab reports, and history of scientific usage

The OP asks: In effort to prevent this from becoming an opinion-based argument, can anyone point me to a major scientific journal's style sheet or instructions to authors that specifies passive voice for scientific communication?

Passive Voice or Active Voice Use the active voice except where you have a good reason to use the passive. The active voice is the natural voice, the one in which people usually speak and write, and its use is less likely to lead to wordiness and ambiguity. Avoid the "passive of modesty," a device of writers who shun the first-person singular. "I discovered" is shorter and less likely to be ambiguous than "it was discovered." When you write "experiments were conducted," the reader cannot tell whether you or some other scientist conducted them. If you write "I" or "we" ("we" for two or more authors, never as a substitute for "I"), you avoid dangling participles, common in sentences written in the third-person pasive voice ... Although frequently misused and abused, the passive voice has proper uses in scientific writing. It may serve when the agent of action (the discoverer and the publisher in the examples below) is irrelevant in the context.

Penicillin was discovered in 1929.
Darwin's Origin of Species was published in 1859.

The passive voice can be used to emphasize something or someone other than the agent. Whether your write "antibiotics are produced by fungi" or "fungi produce antibiotics" may depend upon whether you with to emphasize antibiotics or the agent, fungi. Council of Biology Editors Style Manual: A Guide for Authors, Editors, and Publishers in the Biological Sciences, Fourth Edition (1978), p.21

The ACS [American Chemical Society] Style Guide: A Manual for Authors and Editors (1986) discusses verb tense, but does not distinguish active and passive voices. Nonetheless, the authors' use of the passive voice is pervasive in the model sentences offered, especially those typical of the "Experimental Section" or "Materials and Methods" section of papers.

Some bullet points under Writing Style (p.2):

• Use the active voice whenever possible. It is usually less wordy and unambiguous:

Poor
The fact that such processes are under strict stereoelectronic control is demonstrated by our work in this area.

Better
Our work in this area demonstrates that such processes are under strict stereo electronic control.
...
• First person is perfectly acceptable where it helps keep your meaning clear:

Jones reported xyz, but we found... Our recent work demonstrated... For these reasons, we began a study of...

However, phrases like "we believe", "we feel", "we concluded", and "we can see" are unnecessary, as are personal opinions.

• Try not to shift verb tenses within the same paragraph and section. However, the tense should change from section to section. Present and past tenses are correct in the introduction: "Absolute rate constants for a wide variety of reactions are available. Jones reviewed the literature and gather much of this information. Simple past tense is correct for describing your procedures: "The solutions were heated to boiling", "the spectra were recorded". Then use present tense to discuss your results and conclusions.

As SS pointed out in the Comments, beginning every sentence with I or We would be annoyingly repetitive. It's also unnecessary, as the CBE guide points out. I believe that the authors of ACS guide think this is goes without saying, since it is the default tense in many journals for the experimental section. When they speak of the past tense it is understood that this includes its use with the passive voice.

In the Grammar section of Chapter 2 we have:

Subject—Verb Agreements
...
Incorrect
Application of this technique to studies on the phytoplankton biomass and its environments are described. (The subject is "application", which is singular.)

Correct
Application of this technique to studies on the phytoplankton biomass and its environments is described.

We see this throughout the section:

Incorrect
The series are arranged in order of decreasing size.

Correct
The series is arranged in order of decreasing size. (Refers to the series as a unit.)

Incorrect
A Series of compounds was tested.

Correct
A series of compounds were tested. (Refers to each compound.)
...
Compound subjects contain the words "Each", "every", and "everybody" may take singular verbs.

Examples
Every rat injected and every rat dosed orally was included.

Everybody in the group and every visitor is assigned a different journal each month.

A series of compounds was tested.

Each flask and each holder was sterilized before use.

Passive Voice

Advantages of passive voice:

• minimizes or leaves out the role of the person performing an action (for cases where you do not know who did it, do not want to mention who did it, or who did it is irrelevant)
• softens the tone or makes the message less personal

Disadvantages of passive voice:

• makes the sentence wordy and awkward
• adds formality NCBI Style Guide (National Center for Biotechnology Information)

A dissenting "voice"

How can we account for the popularity of the passive voice? I suggest two major factors. The first relates to defects in our educational system.... The second factor has to do with a mistaken notion about science and its relation to "scientific" communication. The alleged objectivity of science has hypnotized many otherwise capable scientists, who regard anything subjective as tainted, to be avoided as much as defective instruments or contaminated solutions. The logic is simple. The active voice will necessarily require abundant use of the first person...to be avoided as unscientific; the only alternative is the passive voice which, by avoiding the first person, becomes the favored mode of expression.

With this point of view I must disagree in the strongest possible terms. I maintain that objectivity in science is a myth, and that if the devotee of this mythology would apply themselves to clear expression rather than to indefensible dogma, we would have a far greater general benefit.

I am reminded of a seminar in medical writing that I once gave to a group of residents. I pleased for fewer passive constructions and greater use of the first person. When I had finished, several residents mentioned that the head of the department, who reviewed all manuscript, positively forbade any use of the first person. Everything had to be in the third person, even when a resident was applying for a research grant. Such a blanket rule, as it spreads the illusion of objectivity, also encourages use of the passive. All I can do is to exhort my readers not to follow this example. Why Not Say It Clearly: A Guide to Scientific Writing, Lester S. King, M.D. (former Senior Editor and later Contributing Editor of JAMA) (1978) pp.31-32

Some guidelines I've found that insist on the passive voice...claim that this is done to de-emphasize the role of the investigator, and thus provides a tone of objectivity.

Such arguments never seem to have attribution. Is this a commonly accepted reason, or simply a rationalization?

I had a quick look at the earliest texts available online from the Proceedings of the Royal Society. These include letters and experiments written in the first person.

It may be that this pervasive passive evolved by natural selection and the guides came later. The passive voice is a good fit for scientific writing when the subject is unimportant and its omission doesn't lead to ambiguity. The perfect example (and perhaps the origin) is its use for describing the steps of a procedure intended to be replicated. Natural selection requires replication, and as for getting published, When in Rome...

As to whether passive voice is correct in this context, I'm thinking of telling my students that there has been a historical tendency to use passive voice for scientific communication, but there seem to be recent trends promoting active voice.

With regard to advice for students, I would prepare a handout and perhaps discuss in class the pros and cons of the passive voice as presented in style guides like the above, with examples illustrating both good and bad usages of both voices, along with suggestions for rewording the bad examples. I would emphasize that active is the default voice and that the passive has some merits, but it can be abused.