In
Modern English Usage (1926), Fowler argues the case for limiting
that to what he calls “defining clauses” and reserving
which to introduce “non-defining clauses.”
Note: Fowler’s terms
defining and
non-defining correspond to
restrictive and
nonrestrictive.
Yet, here we are, more than 80 years later, and questions about when to use
which and when to use
that to introduce a clause are among those most commonly asked at this and other grammar sites.
The usual explanation begins like this:
THAT should be used to introduce a restrictive clause.
WHICH should be used to introduce a non-restrictive clause.
For starters, let’s look at the terms
restrictive and
nonrestrictive.
In my own experience of learning grammar, I had a hard time trying to
keep these terms straight. Perhaps I have too much imagination, but I
kept thinking that the “restrictive clause” was the one that ought to
have the commas, because, well, commas enclose things, don’t they? And
enclosing something restricts it, no?
The editors of the
Associated Press Stylebook must be aware of mindsets like mine because they reject the terms
restrictive and
nonrestrictive in favor of
essential and
nonessential:
These terms [essential and nonessential] are used in this book instead of restrictive…and nonrestrictive… to convey the distinction between the two in a more easily remembered manner. –AP Stylebook
These alternative terms certainly make it easier for me remember the distinction. The word
essential
means “absolutely necessary.” An “essential clause” is critical to the
reader’s understanding of what the author has in mind; a “nonessential
clause” is perhaps helpful or interesting, but can be omitted without
altering the principal meaning of the sentence. Ergo,
the nonessential clause is the one that gets the commas.
The nonessential clause is also the one that gets the
which.
Mind you, using
which to introduce an essential clause is
not the unpardonable sin some readers–chiefly American–insist that it
is. Writers of British English often use
which to introduce an essential clause. Here are just two examples from sources committed to the dissemination of impeccable English:
We may link to external sites which give particular views
of a person or organisation significant to a current news story… –BBC
style manual.
The Royal Charter which governs our work sets out the objects for which we exist. –British Council website.
In the first example, particular sites are meant; in the second, a
particular royal charter is being referred to. Both of these
which clauses are restrictive/essential.
Banning the use of
which to introduce essential clauses is a
stylistic decision, not a grammatical necessity. Even the premier
American style guide admits as much:
Although which can be substituted for that in a
restrictive clause (a common practice in British English), many writers
preserve the distinction between restrictive that (with no commas) and nonrestrictive which (with commas). –Chicago Manual of Style, 6.22.
That
Chicago does not approve of using
which to introduce an essential (restrictive) clause is made clear in the section titled “Good usage versus common usage”:
In polished American prose, that is used
restrictively to narrow a category or identify a particular item being
talked about: “any building that is taller must be outside the state”; which
is used nonrestrictively—not to narrow a class or identify a particular
item but to add something about an item already identified: “alongside
the officer trotted a toy poodle, which is hardly a typical police
dog.”–CMOS
That for essential clauses and
which for nonessential clauses is without question the preferred American usage. And although
which is still being used in British English to introduce some essential clauses, according at least one British style guide,
that is edging it out:
Restrictive [i.e., essential] clauses relating to things may begin with either that or which, although there is an increasing tendency for that to be preferred. – Penguin Writer’s Manual, p. 32.
Here are some sentences that reflect the preferred
that/which usage:
The car that I want is out of my price range. (essential clause)
The car, which is only two years old, sold for $2,000. (nonessential clause)
The kitten that has white paws is the one I want. (essential clause)
The kitten, which was Jack’s favorite, never came back. (nonessential clause)
