| Take-home: active constructions are usually best, but the passive voice is sometimes appropriate. |
Writing guides rarely say anything positive about the passive voice (positive things are rarely said about the passive voice by writing guides). However, scientists carry on using it, as in:
‘Seed is widely considered to be an important input to agriculture.’
or
‘The survey tool was developed in consultation with farmers’ representatives and local experts.’
So, what is wrong with the passive voice?
Two main things.
First, a phrase like ‘The survey tool was developed in consultation with …’ is ambiguous, unless the authors make it clear elsewhere that they did the developing.
Sometimes, the ambiguity may be deliberate; for example, some may feel more comfortable in hiding behind a phrase like:
‘It seems likely that incomes will continue to fall.’
rather than making a clear assertion like:
‘We think it likely that incomes will continue to fall.’
Deliberate ambiguity is perhaps acceptable in politics and law, but not normally in science.
Second, passive construction is more difficult for the brain to process. We seem to be programmed for the standard subject–verb–object sequence:
‘We analyzed the soil samples.’
is easier on the brain than:
‘The soil samples were analyzed by us.’
In spite of this, the passive voice is very common in scientific writing. Scientists don’t tend to be bashful about their work and the credit due to them, so I doubt that this is due to modesty. I suspect that scientists’ sharp focus (obsession, even) on the subject of their research is one explanation. These subjects often correspond to the objects of active sentences (‘We weighed the adult turtles‘). When scientists write, what is foremost in their minds (research subject, grammatical object) spills out first, and the rest of the sentence is then built around it:
‘The adult turtles, defined as all individuals that had reached sexual maturity, were fitted with tracking devices, and then measured and weighed before release.’
Such writing is indeed passive, because we are going with the flow of our thoughts, rather than thinking how best to express them.
However, the passive may sometimes be the best choice. We may want to stress or make a specific point about the object of the sentence:
‘Focus groups, rather than individual interviews, were used because of time limitations.’
may work better than:
‘Because of time limitations, we used focus groups, rather than individual interviews.’
Or
‘Ronald Fisher is considered by some to have been the father of quantitative genetics.’
may work better than:
‘Some consider Ronald Fisher to have been …’
The passive voice can also be appropriate in two standard components of scientific articles: the Methods section and the Abstract. Readers often scan abstracts without looking at the list of authors, in which case the impersonal feel of the passive seems natural. In Methods sections, careless use of the passive may lead to ambiguity (see above), but in simple descriptions of procedures it can be more elegant than multiple repetitions of ‘I’ or ‘we’. In both cases, our experience as readers also aids comprehension: we are used to finding the passive in these sections, and therefore find it easier to process when it appears.
In general, though, neither concision nor clarity are well served by the passive voice. Careful re-reading of first (or even final) drafts usually reveals multiple cases of passive sentences that would be better phrased as active constructions. the passive voice enhances neither concision nor clarity. Careful re-reading of first (or even final) drafts usually reveals multiple cases of passive sentences that writers could usefully rearrange as active constructions. So, use the passive when appropriate … but don’t be passive about it!