We use relative pronouns – that, which, who and whom – to join sentences, which refer to the same noun, together. (In this post, I’ll look at the difference between that and which, and next week I’ll look at who and whom.)
- We use relative pronouns to join sentences together. The sentences refer to the same noun.
In this example, we have a repeated noun: sentences. We can make this text into one longer sentence that reads more smoothly by replacing the repeated noun with a relative pronoun:
- We use relative pronouns to join sentences, which refer to the same noun, together.
(See how the relative pronoun is kept close to its antecedent: sentences.)
Choosing which relative pronoun to use can be tricky. Rules have developed about when we should which and when we should use that as relative pronouns. Grammarians have tended to regard the difference between the two words as more of a grey area, and there are many examples, from Shakespeare and other notable writers, of that and which being used contrary to the ‘rules’. But Microsoft Word’s grammar checker has been programmed with these rules and I believe this is making the ‘rules’ about that and which more rigid.
The technical explanation is that we use that for defining clauses and phrases and we use which with non-defining clauses and phrases. Just to complicate things, some experts use the terms restrictive and non-restrictive rather than than defining and non-defining, so you have two different sets of jargon to remember. That doesn’t really help if you don’t know what these terms mean (including clause and phrase).
I have found that it is easier to explain the difference with examples, and that these tend to help people remember not only the difference in usage between that and which but also help them to understand the technical explanation.
Imagine you are standing at the Elizabeth Street tram terminus in Melbourne. There are a number of different tram routes that leave from here, going to various well-known attractions. Perhaps a tourist in Melbourne asks you for directions, or perhaps you need to ask someone for directions. Consider the difference between these answers:
- To get to the Queen Victoria Market, just take a tram, which will go along Elizabeth Street.
- To get to the university, just take a tram that will go along Royal Parade.
- To get to the Children’s Hospital, just take a tram that will go along Flemington Road.
Try to answer this question: which tram must you take for each destination?
In speech, we can tell the important information in a sentence from where people pause, the speed with which they talk and the emphasis they put on different words. I have made an audio recording of the examples, which you can listen to by clicking on the play button, to help you understand the differences between the examples.
The answers to which tram you must take for each destination are these:
- For the Queen Victoria Market, you can take any tram (they all go along Elizabeth Street to the market).
- For the university, you can only take the trams going along Royal Parade.
- For the hospital, you can only take the trams going along Flemington Road.
The obvious difference is that one of these examples has a comma followed by which; the other two have that and no comma, and these differences create the differences in meaning.
How are these differences in meaning created? In the first sentence (Queen Victoria Market), we use a comma and which to show that the information that follows is non-definining or non-restrictive; this simply means that the information after the comma is not critical to the meaning of the first part of the sentence. We could actually leave the second part of the sentence out:
- To get to the Queen Victoria Market, just take a tram.
The uncertain traveller will still get to the market, because all the tram routes go there. Just to be helpful (so that the traveller doesn’t perhaps turn around and take a Flinders Street tram), there’s a little bit of extra information ‘which will go along Elizabeth Street’.
With both the university and the hospital, the information after the relative pronoun is crucial: if that information is left out, the poor traveller may never arrive at the correct destination
- To get to the university, just take a tram.
- To get the Children’s Hospital, just take a tram.
The traveller needs to take either a tram that turns down Royal Parade (for the university) or down Flemington Road (for the hospital): the extra information is critical to the meaning of each of these examples. When the information after the relative pronoun is vital to the meaning of the sentence, we call the whole group of words a defining or restrictive clause.
Just to be more complicated, there are occasions when you will have that following a comma, usually in a list of defining clauses:
- You may find that this is a complicated topic, that trying to remember the examples doesn’t help you and that you wished English was easier.
And that’s the basic difference! (You might also find it handy to revise the use of commas, and how we use them to show meaning and group words together, to help reinforce the difference between defining and non-defining clauses.)
MS Word’s “That” or “Which” message
If you have ever used MS Word’s in-built grammar checker on a document, you may have seen this message:
What the grammar-checking tool is trying to tell you with this message is that you need to work out whether or not you have used a defining or non-defining clause, and to use a comma and which for a non-defining clause or that with no punctuation for a defining clause. How can tell you whether you have a defining clause or non-defining clause? Try dropping the words after your relative pronoun, and see if the meaning changes (just like the tram destination examples above).
- The worm was Wally.
This leaves out vital information for identifying Wally: the fact that the original sentence said ‘which wriggled worst’ implies that there are a number of worms, and the one doing the most wriggling is Wally. The detail about wriggling is vital to the meaning of the sentence; it is a defining clause. The grammatically correct version of the sentence is thus this:
- The worm that wriggled worst was Wally.
This difference is usage and meaning between that and which is one of the hardest topics in English to understand: when I first learnt about it, I had to keep saying in my head sentences about how to get places to remember the difference. Keep at it: the more you think about it – or the more you think about the examples above – the easier it will become.
So enjoy this long weekend. If you went to the races at Flemington on Saturday, or will be going next weekend, just think: to get to Flemington racecourse from the Elizabeth Street tram terminus, just take a tram that will go along Racecourse Road!
If you have found this post interesting, you can find a full index to my other posts on the index page. To be notified when I post a new topic, follow me on Facebook! If you have any particular questions you’d like me to answer in future posts, just send me a message. I’m always interested to learn what people think, and how you came across this site, so please post a comment.
If you think you would be interested in either my complete grammar course or an individual customised online course (particularly suited for people who don’t live in Melbourne), just click your preferred option.
Photos: Elizabeth St Tram Terminus © and by kind permission ThebusofdoomFSX, https://www.youtube.com/user/ThebusofdoomFSX/videos; Queen Victoria Market by Crisco 1492 (CC BY-SA 4.0), University of Melbourne by Donaldytong (CC BY-SA 3.0), Children’s Hospital by Whatmov (CC BY-SA 3.0), and Flemington racecourse by Chris Phutully from Australia (CC BY 2.0), all on Wikimedia Commons; for details of Wikimedia Commons licences, see the copyright page