'Which-hunting' and the hegemony of style guides

The article examines the significant impact of mass-market manuals to systematically change the way that writers use the English language. Advice books such as Strunk and White's Elements of Style, or Fowler's Modern English Usage have been able to systematically influence generation after generation of students in much of the English-speaking world. The new study demonstrates the importance of prescriptive grammar as a social force and its steady increase over the course of the twentieth century.

The authors of the study, Lars Hinrichs and Axel Bohmann, of the University of Texas at Austin, and Benedikt Szmrecsanyi, of KU Leuven, show that these changes can sometimes be rather drastic. To introduce relative clauses, English writers (especially American ones) now clearly prefer the relative pronoun that (as in the sentence: This is the book that impressed me), whereas in the middle of the twentieth century, the use of which (as in This is the book which impressed me) was still much more common. This shift dovetails with recommendations in style guides to go which-hunting, and to instead use that in defining relative clauses.

For this research, the linguists studied 16,868 relative clauses that appeared in written publications in English from either Britain or the US, and which were published either in 1961 or in 1991/1992. In each of these cases, writers would have been able, in principle, to use either that or which as relative pronoun. The study found that there is a very significant shift from the early 60's to the 90's, in writers' preferences for that at the expense of which. Regression analysis also reveals an interesting pattern when linguists look at who the writers are that prefer to use that over which. The same writers are the ones who on the one hand follow another rule from prescriptive style guides, "avoid the passive voice." On the other hand, writers preferring to use that tend to disproportionally often end sentences in a preposition (the house which I looked at), which is proscribed.

As a result, usage of relative that, avoidance of the passive, and ending sentences in a preposition all go hand in hand, and crucially, all of these options are rather informal. Relative that, for example, is the variant that people normally use when they talk. The study thus reveals an important fact about prescriptive grammar: it is most successful in changing usage if what it prescribes is more informal than alternative options.