What vs Which
What vs which – what should I use?

Which vs what – what should I use?

Think those sentences mean the same thing? Maybe you’re right. But there’s still a correct way to use each of them, as each has a different meaning.

Word usage questions are something we receive a lot of on Versus All. And what vs which seems to be causing a bit of mass hysteria, so let’s tackle the debate head on. What vs which – which should you use?

What vs Which: The Basics

We would ordinarily start our exposition by defining the words what and which. But it seems that would take up the entirety of our space on this page, so we’ll make it a bit more simplified.

First, let’s look at what vs which when they’re used in sentences.

  • What would you like on your sandwich?
  • I have olives and pimentos; which would you like on your sandwich?

In the first sentence, we don’t know the number of sandwich topping possibilities. There could be two options or there could be an infinite number. Using the word what in this sentence leaves it open-ended.

In the second sentence, there are two options. There are olives and there are pimentos. The sandwich artist is asking the sandwich eater which of these options he would prefer.

Now, look at the following sentence:

  • I have olives and pimentos; what would you like on your sandwich?

The meaning of the question is essentially the same. The sandwich eater understands that there are two options for his sandwich and that it’s now up to him to decide between those two. However, while it’s still understandable and technically makes sense, it’s not grammatically correct to use what in this sentence.

In the what vs which debate, there’s one sure way to determine which to use. What is used when there is an infinite or unknown number of variables. Which is used when there are a finite number of variables.

What vs Which: Let’s Confuse the Issue

Let’s imagine you’re playing a guessing game.

  • I’m thinking of a number between one and ten; which is it?

Or perhaps you’re playing Eye Spy.

  • I spy with my little eyes an object in this car; what is it?

The numbers one through ten are definitely finite. There are ten. The number of objects in the car is finite as well. There are probably somewhere around four thousand, six hundred thirty four. But it’s more commonly accepted that what is the correct word to use in the second sentence.

It’s in this way that sometimes the use of what vs which can be objective. Here’s an example:

  • What color is your trash can?
  • Which color is your trash can?

Both sentences are correct. But in the second question, the person inquiring probably has just a handful of possibilities in mind. In the first sentence, the possibilities seem endless. Context plays an important role in determining whether to use which or what.

Setting will also play an important part in which word you choose. In a more formal setting, you may choose to use the word which when grammatically appropriate. In an informal, relaxed setting you can pretty much use whichever you like. Your friends will still know what you’re talking about.

What vs Which: More on Context

Our aim is to clarify grammar for you, not to confuse you. But we’d like to offer one more example of how context is important in deciding which word to use.

  • What movie would you like to see?
  • Which movie would you like to see?

Both may be considered correct. However, there are a few ways in which you can view a movie. You can go to see one in a theater, and in this case there are probably only 10 or so options. Alternatively, you can rent or stream a movie, in which case the options may seem limitless.

What movie would you like to see” is probably what a speaker would say when referring to Netflix or Amazon Prime. There are thousands of options. “Which movie would you like to see” is probably a question which refers to the theater. The speaker may be asking about which movie, which showing or which cinema.

Only the speaker and the listener know for sure, so when you’re writing it’s important to clarify the variables. Provide context clues or be outright in your explanation of those variables. Doing so will also make it easier for you to choose.

What vs Which: But This is the 21st Century

What or Which

Yes, it’s the 21st century. And it’s likely that if you post what instead of which on a Facebook post, no one will troll you relentlessly. But consider this tweet:

4 sell by onr 18” #RCA FS TV 50bux hmu

You understand what that means, right? Some guy’s got a flat screen for sale and he wants you to “hit him up” if you’re interested. Is it a sentence? No. Would anyone in a professional setting consider that to be an adequate way to communicate? Hell no.

It may make us sound old, but we at Versus All are firm believers in the preservation of language. All language. It’s why we do what we do. We’ve written about who vs whom, that vs who and we’ve droned on about the importance of never using “could care less.” You know what that tweet meant, and you also know what a writer means when he uses which vs what and vice versa.

It’s the 21st century, but we’ve still got to maintain some sort of method of understandable communication. Sure, we all slip up and use what when we should have used which, or used Miss when we meant Ms. But having a basic understanding of the correct use will help to ensure that the English language doesn’t become reduced to a series of hashtags and txtspk.

On the whole, what and which are largely interchangeable. When you’re dealing with a finite number, use the word which. When the options are more vast, use what. Everyone will understand what you mean if you make a mistake, but know the difference so you can use the correct word when you need to.

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