Denise M Taylor

Writing Consultant I Editor I Proofreader

Are you sometimes unsure whether you should use ‘that’ or ‘which’ in a sentence? If so, join the throng; or maybe you’ve never really thought about it. Fair enough. In many cases, both words are equally correct. However, you can keep this in mind: ‘that’ introduces essential (restrictive or defining relative) clauses, and ‘which’ introduces non-essential (non-restrictive or non-defining relative) clauses.

Let’s take a look at this sentence:

The Picasso that was purchased last year by the gallery is in the exhibition.

If the essential clause beginning with ‘that’ (that was purchased last year by the gallery) was omitted then we would not be able to identify the recently purchased Picasso painting on display in the exhibition. Note that you do not need a comma around the clause. Let’s add a non-essential clause to the sentence:

The Picasso that was purchased last year by the gallery, which cost $3 million, is in the exhibition.

The Picasso is already identified, so the non-defining relative clause beginning with ‘which’ (which cost $3 million) is not essential as it just tells us what the gallery paid for the painting. Note these non-essential clauses are enclosed by commas if they are in the middle of the sentence, or preceded by a comma if at the end. If the clause was left out of the sentence then the meaning would not change.

There is always that old ‘chestnut’—ambiguity; it can hurt your intended meaning. For example, if you leave out the comma in the following sentence it is unclear whether all the toys were damaged and never sold, or whether there were only a few damaged that remained unsold:

The toys which were damaged were never sold.

 Commas around the non-essential clause make the sentence clearer:

The toys, which were damaged, were never sold.

If we substitute ‘which’ with ‘that’ and create an essential clause then the information contained in the clause defines or limits the subject (the toys) and there is no need for commas.

The toys that were damaged were never sold.

 And so on . . .

I bought a new coat, which I will be wearing to Europe. (non-restrictive clause)

I was wearing the coat that I bought to wear to Europe. (restrictive clause)


If we make this as simple as possible, use ‘that’ before an essential clause and ‘which’ (or ‘whose’, ‘who’ or ‘whom’) before everything else.


. . .  and from Murray Bail’s Eucalyptus(1998):

It is this chaotic diversity that has attracted men to the world of the eucalypts.

The very word ‘eucalyptus’, which many would swear is the loveliest of all words, was for Ellen an unbearable word, a bearer of troubles.


 Fun with ‘which’ and ‘that’:

That which comes before must always be considered when studying history.

Say that again?

Which is the right way up? Oh, THAT way!

I used to know that. Which was what?

And my favourite weasel:

Having said that . . .



Writing Business Content for the Web

One Response so far.

  1. Barrie Sheppard says:

    Clear as a bell, Denise!
    “That that that that man wrote should have been which.”

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