I don’t use the grammar check on Pages for Mac at home, but I do on Word for Windows and Mac at two workplaces. Even if I ignore it nine times out of ten, it saves my backside the tenth time, with all the copying/cutting, pasting, adding and deleting of text I do. A few weeks ago it flagged three instances of passive voice. It correctly identified passive voice, but its suggestions for change were wrong. (It actually flagged more than that. I took photos of three then gave up.)
Firstly, there is nothing inherently wrong with passive voice such that it needs to be flagged every time, in the same way as, say, subject-verb number disagreement, which is always wrong. Even the most anti-passive style advisers, such as Strunkandwhite and George Orwell, use passive voice perfectly when appropriate. Secondly, if you’re going to suggest changing it, then make absolutely sure that your suggestion is right.
But that is not easy for a computer to do, as these three (slightly adapted) examples show.
1) Protection is provided by defining a safety area, whose shape and dimensions must be specified according to a risk assessment.
Suggestion: Defining a safety area, whose shape, provides protection [plain wrong]
2) Alerts and reports are provided by [this software] displaying information in an intuitive and easy-to-read format.
Suggestion: [This software] displaying information in an intuitive and easy-to-read format provides alerts and reports [mostly wrong]
3) Areas of the multi-purpose centre have already been made available for use by community groups offering support and services to [this organisation’s] customers.
Suggestion: Community groups offering support and services to [this organisation’s] customers have already made areas of the multi-purpose centre available for use [possibly right, but not]
Quick recap of active and passive voice: in active voice, the grammatical subject of the sentence is usually* the semantic ‘do-er’ of the action, and the grammatical object is usually the the ‘done-to’. In passive voice, the semantic ‘done-to’ becomes the grammatical subject, and the semantic ‘do-er’, if she/he/it/they is specified, is in a by-phrase. But the ‘do-er’ can be omitted and there are other things a by-phrase can mean. (*As usual with English grammar, it’s more complicated than this, but that explanation will have to do for now. For a full explanation, see here.)
In 1), the doer is the safety system under discussion, which has been identified and discussed in previous paragraphs, so it can be omitted. by defining a safety area is the means by which the system provides the protection. We could write Protection is done by this system by defining a safety area, but that’s too much by.
In 2), the alerts and reports are provided by the software (doer) by displaying information in an intuitive and easy-to-read format (means). So the active voice equivalent would be [This software] provides alerts and reports by displaying information in an intuitive and easy-to-read format. There is a further complication here in that displaying information … just might function to identify which software provides the reports. But this would be more likely if the subject was Software displaying information in an intuitive and easy-to-read format provides …
Finally, in 3), the doer of the main action (the making available of areas of the multi-purpose centre) is the owners of the multi-purpose centre. by community groups attaches not to have been made available, but to available for use. The grammar check can’t find this doer, because it has been omitted. Even the most sophisticated grammar check in the world will never be able to find something that’s not there.
And it’s not just long, complicated sentences. Consider:
4) Stolen painting found by 3-year-old
5) Stolen painting found by tree
6) Stolen painting found by ESP
In 4), the 3-year-old is the doer, so we can easily change it to 3-year-old finds stolen painting. In 5), the tree is the location, so we can’t change it to *Tree finds stolen painting. Compare Stolen painting found near tree, which a computer would probably not recognise as passive voice. In 6), ESP is the means. Maybe – just maybe – we can change it to ?ESP finds stolen painting. Compare Stolen painting found using ESP, and especially 3-year-old found using ESP, which is ambiguous (who was using ESP – the 3-year-old or the finders?).
So, given that the doer can be omitted and the by-phrase can mean different things, it will be a long time before computers can reliably suggest the active voice equivalent of a given passive voice sentence. I wonder if anyone would passively (haha!) accept any or all of these suggestions.
In the meantime, this grammar check missed another instance of passive voice: whose shape and dimensions must be specified according to a risk assessment, which lacks the by-phrase (by whoever is in charge of configuring the system). I’m actually more worried about whose, so maybe I changed it to the shape and dimensions of which must be designed … There were also two other questionable points which I have edited here for simplicity, and probably edited that day at work.
Hopefully, publishers realise they need human subeditors really subediting.
PS Another thought. Even if grammar checks ever get to the point where they can unfailing analyse passive voice and suggest active voice equivalents, the reasons for using passive voice include focus (who or what are we talking about?) and what I will call flow of ideas (how are we linking this sentence to what has come before it?). It will be long time before a grammar check can reliably get those right.
Never Pure and Rarely Simple 