
“Caesar, thou art revenged, / Even with the sword that killed thee.” This pivotal verse from Shakespeare’s Julius Caesar uses “that” to introduce a restrictive clause, which means it provides essential context. But sometimes, you’ll see similar sentences incorrectly written with “which,” as in, “Even with the sword which killed thee.” Although these sentences convey the same meaning, the latter is actually a grammatical error. Here’s how to get it right.
The distinction between “which” and “that” can confuse even the most experienced writers.The key to using these words correctly lies in distinguishing between restrictive and nonrestrictive clauses. A restrictive clause provides critical information about the noun it modifies. You can’t remove the clause without altering the sentence’s meaning. For example, “The book that I borrowed is on the table.” The intent of the sentence is to specify the borrowed book, not just any random book, so “that I borrowed” is necessary information. A nonrestrictive clause, however, adds extra detail that can be omitted without changing the sentence’s core meaning. For instance, “The novel, which I read on the bus to kill time, was a thriller set in Nantucket.” Remove “which I read on the bus to kill time,” and the sentence still makes sense: “The novel was a thriller set in Nantucket.”
The key to this word choice typically relates to comma usage. Use “that” for restrictive clauses (no commas) and “which” for nonrestrictive clauses (with commas). For example: “The pen that I broke is in the trash” (restrictive), versus “The pen, which I bought in Maine, broke in my purse” (nonrestrictive).
If you’re still having trouble telling them apart, don’t sweat it. Even Shakespeare wasn’t so strict about this rule. In The Winter’s Tale, he wrote, “It is a heretic that makes the fire, not she which burns in’t.” Current grammar rules would dictate “that” in the restrictive clause, but Shakespeare wrote in what’s called Elizabethan English, which is a precursor to modern English, and the rules don’t exactly match up. It’s also worth noting that Shakespeare’s works were meant to be performed on a stage, and it’s less likely that someone will nitpick your use of “that” versus “which” in spoken word.