THERE ARE SEVERAL SIMILAR WORDS IN THE ENGLISH LANGUAGE that cause a high degree of confusion: those who use them don’t always understand the correct word to write. This article will shed some light on the use of ‘that’ and ‘which’.

The simple rule to follow here is in asking if the portion of the sentence following ‘that’ or ‘which’ is vital to the understanding of that sentence. If what you read is vital to the understanding, then use ‘that’. If what you read is not vital to the understanding and can easily be removed without upsetting the meaning of the sentence, then use ‘which’.

‘That’ is used in what are known as defining, or restrictive, clauses: what follows ‘that’ is something you can’t get rid of; it restricts or defines the sentence.

So, for example:

The car that travelled at speed was blue.

This implies that there were many cars, but the one that was going fast was blue.

‘Which’, on the other hand, is used in non-defining, or non-restrictive, clauses: what follows ‘which’ is something you can remove; it does not restrict or define the sentence.

So, for example:

The car, which travelled at speed, was blue.

This implies that there was only one car and that we’re not so concerned by its speed. The sentence is making reference to the car and what colour it was. The portion of the sentence between the commas can be removed and the intended meaning of the sentence (that the car was blue) is still intact.

Here are some more examples of ‘that’ and ‘which’:

The book that he loved was left on the train.

(The implication is that this book was loved).

The book, which he loved, was left on the train.

(The implication is that this book was left on the train and, by the way, he loved it).

The dog that eats from the bowl is growling.

(The implication is that there are many dogs but this one is eating and growling).

The dog, which eats from the bowl, is growling.

(The implication is that the dog is the only dog in the scene. The dog is growling and, by the way, it’s also eating).

I saw ten animals that I didn’t recognise in the zoo.

(The implication is that there were more than ten animals seen in total, but these were the ones not recognised).

I saw ten animals, which I didn’t recognise, in the zoo.

(The implication is that there were only ten animals seen in the zoo and, by the way, they weren’t recognised).

In all of this cases, use of ‘that’ highlights important information and use of ‘which’ shows us easily omitted information. We can also use the same thinking when what follows ‘which’ comes at the end of a sentence.

So, for example:

Neutrinos might travel faster than light, which is an amazing idea.

This use of a comma and ‘which’ could easily be replaced by a full stop and ‘This’:

Neutrinos might travel faster than light. This is an amazing idea.

In conclusion, ‘that’ and ‘which’ are often confused. By thinking about what the sentence you’re writing is trying to convey, confusion can be eliminated.

— Rafael Shareef
 
 

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