Substituting 'That' for 'In Which': A Comprehensive Guide

When writing in English, authors often have the flexibility to choose between different relative pronouns to enhance clarity and style. Among the most common choices are 'that' and 'which.' This article will explore the nuances of using 'that' in place of 'which' in relative clauses, focusing on both defining and non-restrictive clauses.

Defining Relative Clauses: 'That' as a Substitution for 'In Which'

In defining or restrictive relative clauses, the relative clause is essential to the meaning of the sentence. It serves to identify or modify the antecedent clearly. For instance, in the sentence 'The road that/which is under construction will link our village to yours,' the relative clause 'that/which is under construction' is necessary to specify which road is being referred to.

When the relative clause is defining, 'that' and 'which' can be used interchangeably. A defining relative clause does not require a comma before it, as it is closely linked with the antecedent. The pronoun 'that' can be seen in both sentences as a direct object in the relative clause, such as in 'The book that/which you're reading must be fascinating!'

Non-Restrictive Relative Clauses: The Importance of Commas

In contrast, non-restrictive or non-defining relative clauses provide additional, non-essential information. These clauses can be removed without altering the core meaning of the sentence. For example:

All Jack's clothes that were left in the car were stolen.

Here, the relative clause 'that were left in the car' is necessary to specify which clothes were stolen. If we remove the clause, the sentence would change to:

All Jack's clothes were stolen.

However, if we include 'which was left in the car' instead of 'that was left in the car,' the sentence becomes a non-restrictive clause:

All Jack's clothes which were left in the car were stolen.

Notice the difference: 'which' is preceded by a comma, indicating that the information is optional and does not affect the core meaning of the sentence.

Common Usage and Historical Context

Prescriptivists might argue that 'that' should be used exclusively in defining relative clauses, while 'which' should be reserved for non-restrictive clauses. However, in informal English, as well as in some formal contexts, 'that' is frequently used in both situations, blurring the traditional line between these two types of clauses.

The historical origin of this usage is rooted in the evolution of the English language. Old English, which shared many features with other Germanic languages, did not use the 'wh-' interrogative pronouns for relative pronouns. Instead, it used variants of demonstrative pronouns or the predecessor to 'that' for both relative pronouns and interrogatives. The Norman invasion brought the Romance language influence, introducing the use of 'who, whom, which,' etc., for relative clauses. However, 'that' continued to be used by the 'folks,' and in American English, it has become increasingly prevalent.

Key Points to Remember

Use 'that' and 'which' interchangeably in defining relative clauses. Use 'which' for non-restrictive relative clauses and precede it with a comma. Avoid using 'That’s' instead of 'Whose.'

Examples and Further Clarification

To better illustrate the concept, let's consider a few examples:

Defining relative clause: 'All Jack's clothes that were left in the car were stolen.'

This sentence indicates that only the clothes left in the car were stolen, not other items Jack might have at home or wearing.

Non-restrictive relative clause: 'All Jack's clothes which were left in the car were stolen.'

Here, the additional information is that all of Jack's clothes were in the car, and they all ended up being stolen.

Using 'That' in a non-restrictive clause: 'The book that/which you're reading must be fascinating. You can't stop reading it.'

This works because the clause provides a direct object and enhances the sentence without changing its core meaning if removed.

Conclusion

The flexibility of using 'that' in place of 'which' in relative clauses offers writers a valuable tool to enhance their prose. Understanding the distinction between defining and non-restrictive relative clauses, along with the proper use of commas, can greatly improve the clarity and precision of one's writing. By following the guidelines outlined in this article, English writers can achieve a more nuanced and effective use of these important clauses.