Often, people will use the word “which” when “that” is more appropriate. I think they do so because they believe “which” has somehow taken on a more formal or fancy tone (it’s a little bit like the way in which people use “whom” for “who” or “myself” for “me.”

A college professor of mine once gave a lesson teaching us to go on a which hunt, and with Halloween approaching, I thought it a fitting topic to resurrect (leaving us with, I suppose, some zombie whiches).

In general, it’s best to use “which” when the phrase it begins is providing extra information whose absence would not change the basic meaning of the sentence. A phrase beginning with “which” is often enclosed in commas. Consider these two sentences:

Vampire bats that don’t drink blood often go hungry.

Vampire bats, which don’t drink blood, often go hungry.

In the first sentence, we learn that vampire bats that refuse to eat blood go hungry, but there’s an understanding that vampire bats that eat other things may not go hungry. The “that” clause isn’t optional because it specifies a particular condition that must be met to render the sentence properly meaningful. In the second sentence, the “which” statement provides optional information. Vampire bats, whether they drink blood or not, often go hungry (the sentence posits).

Some would have written the first sample sentence above as “Vampire bats which don’t drink blood often go hungry.” It’s missing the commas, which provide a sure sign that the information is extra, but it’s still potentially confusing and is thus better said with a “that” than a “which.” So I encourage you to go on a which hunt when you’re writing and swap out any unnecessary whiches for thats.

For a more detailed breakdown of the rules, you might be interested in heading over here.

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  1. Very meaningful and at the same time entertaining.

    Thanks. Once, I had a laughter when I understood the topic is grammatically written, not witch-ly. haha!


  2. Excellent topic. The “which hunt” concept goes back to Strunk & White (Elements of Style). I recently edited a text written by someone from the UK and had to change dozens of “whiches” to “thats” and he asked why. He’s a good writer (otherwise) and said he’d never heard of this rule. We began to dig around and have found that apparently it’s more common to American English than British.


    1. I know exactly what your saying. It is true that ‘which’ is more common in dependant clauses in British English than in American English. (I’m a British English speaker, by the way.) In many cases, the so-called American usage is actually correct, mainly because it WAS correct British usage until the British education system completely mashed things up back in the 1960s. Another influence is that ‘which’ is commoner in British speech for dependant clauses than in American speech, so it carries over into writing. But I would have to wonder what kind of writer you had to deal with who never heard this rule.


  3. I find my writing is most improved when I omit the use of both which and that – in MOST cases there is a better way to structure the sentence. I was always taught if you use “that” in a sentence, read it out loud omitting the “that” – in many cases you can live without the that.


  4. I am so fueled by proper grammar in writing. Thank you for this lesson. I am often searching the web for similar little lessons to remind me of some of the rules. I will definitely share with my kids and others and on my post.


  5. I’m completely lost on this one Daryl. Why isn’t it just “Vampirebats who…”? When I clicked on the grammar girl link, I was barraged with multiple pops-ups about toothbrushes, that WOULD NOT STOP. I guess I will remain ignorant on which vs. that.


    1. Ugh, sorry about the popups — my browser’s popup blocker must have spared me. As for using “who” instead, my initial example included just vampires, but I changed it to vampire bats, since for non-humans (or at least non-pets), you don’t typically use “who.”


  6. I interpreted the second sentence differently. The additional info implies that vampire bats do not drink blood, but they often go hungry. I’m thinking that construction infers that contrary to general opinion, these mammals don’t imbibe.


  7. This is a good, concise post about that vs. which. But I am a bit saddened by it too – in that so many people STILL haven’t figured out such a basic thing as this – a sad reflection of the state of our education. (For the avoid of doubt, this is NOT a jab at the other commenters!)


  8. Not to put too fine a point on things, those two examples given are in that typical ‘academic’ or grammarbook style of examples – and people endlessly and needlessly go on a rampage of interpreting their meanings because of that. The better deal is just to completely recast them (as I usually do in my editing work) – after ringing the author up to find out exactly what the heck he/she is trying to say. Choice of recasts to fit any bill:

    (1) Non-blood-drinking vampire bats often go hungry. (1st example’s meaning)
    (2) Vampire bats do not drink blood, and they often go hungry [because of…]. (2nd example’s meaning)

    Broadly speaking, it’s more efficient (and more in keeping with the Anglo-Saxon manner of expression) to lash two independent clauses together with some sort of conjunction rather than shove a dependent/independent clause into the middle of a sentence (as is typical in a Latinate manner of expression). Of course, all this depends on the general style of the writing, as much as on the subject matter. Assuming/presuming the writer was talking about vampire bats as a naturalist, most probably it would be better to go for the more concrete-sounding Anglo-Saxon manner of expression than a Latinate one. Overuse of ‘which’ clauses make for insecure-sounding text. Frankly, we’ve got enough problems trying to understand our clients as human beings without having to figure out their writing as well.


  9. Living in a country where English is not the mother tongue I am met with the which hunt every single day… it is amazing how many people become confused when deciding whether to use which or that.

    Another interesting problem I have come across is that people don’t know how to use then and than.


    1. It is unfortunate that many do not know how to distinguish then and than or which and that. In the English languages there are many variations which make it ever so confusing, however a lot of people are able to remember the differences.


  10. This is used in the american language, however in England many times which is used over that. American influence on our culture has caused many to forget that, and therefore many make mistakes. However, quite a few times “that” is the better option.

    The English language is so confusing! 🙂