Following my piece about the usage of comprise two weeks ago, several readers raised a subtle grammatical issue, whose resolution explains why comprised of appeared and why it is gaining in popularity.
The issue centres on my description in the original piece of the comprised of version as a passive construction. A couple of readers bluntly told me that to call it that meant that I didn’t understand the passive. I said it was passive because almost all of the grammar and style guides that I consulted, going back to H W Fowler’s Modern English Usage nearly a century ago, describe it as one.
Help came from an acknowledged expert. Geoffrey Pullum is professor of general linguistics at the University of Edinburgh and co-author of The Cambridge Grammar of the English Language. His first comment was “It’s an extraordinarily tricky topic!”
He said that comprise is a member of a class of verbs that take a noun phrase as their object. With comprise, this noun phrase is the list of the parts that make up the whole, as in “The executive committee comprises the heads of the three main divisions.” A key point is that comprise can’t be followed by a prepositional phrase beginning with of. Many verbs can, including one with a related sense, consist. “The executive committee consists of the heads of the three main divisions” is good English but in the standard language you can’t replace consists of with comprises of.
If you try to turn comprise into a passive, you run into trouble. With the sentence I quoted earlier, you end up with “The heads of the three main divisions are comprised by the committee”, which nobody says. The form is comprised of can’t be a passive, because there’s nowhere for the of to come from. Though genuine passives can contain of, as in “Her dress was strongly disapproved of by her parents”, in those cases the of is also present in the active form: “Her parents strongly disapproved of her dress.”
Professor Pullum pointed out that a similar situation occurs with compose. You can write, “The heads of the three main divisions compose the executive committee” but if you tried to make a passive out of that you would get “The executive committee is composed by the heads of the three main divisions.” Nobody says that either.
But you can say “The executive committee is composed of the heads of the three main divisions.” What has happened, he concludes, is that composed in sentences such as “Water is composed of hydrogen and oxygen” has evolved into an adjective of a type that may be followed by of, in the way that afraid is used in sentences such as “Jack is afraid of spiders.”
In the version, “Water is comprised of hydrogen and oxygen”, people have unconsciously substituted the comprise root for the compose one to make a new adjective, comprised, which can also be followed by of. But while the usage with compose is standard English, the one with comprise is still widely regarded as an error.
What we’re seeing is English quietly evolving through analogy. Of course, few people pay close attention to what they’re saying, or even notice, and as Professor Pullum says, it’s not the easiest construction to analyse anyway.
When you look at it in this way, it’s hard to justify continuing to object to comprised of other than through convention.