When to use which and when to use that is pretty darn confusing for most people. Many of us use the ‘does it sound right?’ rule. Or we use that when we’re being informal and which when we’re being formal. Or sometimes we don’t give a hoot and use that or which interchangeably.
It’s pretty subtle but the rule is as follows:
We use which when we’re adding information.
The books, which have green covers, are new.
So all the books are new. And we’re just letting you know they have green covers as an extra bit of information.
On the other hand, we use that when we are restricting information.
The books that have green covers are new.
We’re being very specific. Only the books that have green covers are new.
Clauses containing which are set off by bracketing commas. Which means they can be removed from the sentence and still make sense.
The books, which have green covers, are new.
The books are new.Â
So to recap. If you’re adding a bit of extra information, just for the heck of it, use which. Otherwise use that. Simples.
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Thank you for that! My writing is often peppered by (with? :) ) an interchanging use of “that/which” depending on the half-understood rules over the years of high school English and reading copy across broadsheets and tabloids.
I half-recall a rule regarding plurals but you seem to have made it a little easier to understand this time ;) Here’s to using it in practice next time I write an entry on my blog….
Hey Liam
No probs! It’s one of those things I have to really think about. That and the lay/lie issue! (See June 12 post.)
Thank you! This was extremely useful for people like me who are not native English speakers :)
In A.E. Darbyshire’s “The Craft of English”, the difference is explained thus:
which – this can be either subject or object and refers to things.
that – this can be either subject or object and usually refers to things.
Subtle indeed.
Hi Eddie
Hmmmm…that’s clear then!
I’ve noticed that people tend to use ‘which’ as a sort of default. There’s nothing like a bit of confident ‘thatting’ to show a writer knows what they’re doing.