Monday, February 23, 2009

A disturbed dog

There are three dogs.

One is in a house. One is in a car. One is in a garden.

One dog barks.

Which dog?

The dog that is in a car barks.

The dog that barked is in a car.

This dog, which has brown fur, barked because it was disturbed.


The difference between "that" and "which" eludes most of us until we get it, and once we get it, we cannot confuse them.

"That" phrases are used to answer the question "which x?". In other words, "that" phrases distinguish things that belong to the same class of things (in my example, the class is "dogs"). "Which" phrases are used to give more information or detail about things that have already been distinguished.

"That" phrases are always essential to the sense of the sentence, so they must not be separated by commas. By essential, I mean that if they were omitted, we would not know who or what the subject of the sentence was, and would need to ask "which...?"

Try it.

"The dog that is in a car barks." Take out the "that" phrase. "The dog barks." Which dog? There are three.

"Which" phrases are never essential in the same way. "This dog, which has brown fur, barked because it was disturbed." can lose its "which phrase", and we still know which dog, because it is specified by "this". Once we have defined which dog we are discussing, we can add information.

Formally, "that" phrases are usually called "defining clauses" and "which" phrases "non-defining" (you may see the terms "restrictive" and "non-restrictive", because the "that" phrase restricts the reference of the noun it modifies). The words tell the story truly: defining clauses select one thing from a class of things that are described with the same noun; non-defining clauses do not (they simply give more information about a noun that has already been defined or restricted). Indeed, they are not all that similar. If I were trying to learn the difference, I would focus on learning what defining clauses do, and then asking whether that is what the thing I want to write does.

The confusion of the two arose because formerly people used "which" for both sometimes, distinguishing them by using a comma.

The comma is key, of course, but we have strengthened the distinction by no longer using "which" to define.

Further confusion can arise because "which" is used to ask for a noun class to be restricted by the listener: "Which dog?" and as a demonstrater in constructions such as "I know which dog you are talking about." Note that "that" and "which" are both described as "pronouns": "which" is clearly one, and you can see that it transparently substitutes for the noun that it is giving more information about; "that" is less clearly one, and I won't go into a technical explanation of why it is.

For practical purposes, although you need to be aware that people use "which" as a defining pronoun, you should use "that" to define and "which" to provide further information. You need only remember that "which" is preceded by a comma, always, and "that" is not. Whenever you know that you do not want to write a comma, use "that". Whenever you feel that you are adding extra information, and consequently have the overwhelming to parenthesise, use "which".

That's that!


At 6:16 pm, Anonymous Anonymous said...

boots sez:

Thanks for your explanation. I'm still a bit fuzzy from sleep this morning so will probably need to read it again a time or three. What I expect I'll do is wait for one of those times when I'm not sure which to use, then come read it then. Should be within the hour. <g>

At 12:30 am, Blogger Robert McClelland said...

Can that be used in place of which?

This dog, that has brown fur, barked because it was disturbed.

At 9:05 am, Blogger Dr Zen said...

No. That would be a solecism this side of 1700.

At 3:55 pm, Anonymous Anonymous said...

I note you have grown a pair at last pity you deleted/disallowed so many of my comments, i thought they were quite funny. Because the truth often is and truth is the first victim of the censor!

At 3:59 pm, Blogger Dr Zen said...

If they were funny, on topic or anything but the rantings of a lonely tard with nothing better to do than try to get my attention, I wouldn't bother deleting them, Guntard.

At 8:21 pm, Blogger Father Luke said...

The commenter, which has had poasts deleted, is that one.

- -
Father Luke

The difference between "that" and "which" eludes most of us until we get it, and once we get it, we cannot confuse them.

True that.

At 9:40 pm, Blogger Dr Zen said...

Well okay, you proved me completely wrong.

"The commenter who has had posts deleted is that one."

This is precisely a case in which you cannot use a "which" clause. (Leaving aside that for people we use "who", you need a restrictive clause, because you are defining which commenter you are discussing.)

At 9:57 pm, Blogger Father Luke said...

for people we use "who"

The commenter who's poasts were anonymous, and who poasted those comments which were deleted, was that one.

- -
Father Luke

At 10:11 pm, Blogger Dr Zen said...

Hmmm. Now I feel my leg is being pulled.

At 10:54 pm, Blogger PJ said...

The commenter who's poasts

Whose, shirley.

At 11:01 pm, Blogger Father Luke said...

Whose that guy with the droopy mustache?

Which mustache?

The mustache which droops,
that's which one.

- -
Father Luke

At 5:31 pm, Blogger Sopwith-Camel said...

LOL, Now Grant has become a lesson to us all!

I think I shall use, as a term to describe anything which has defied the rules and refused to behave as we would expect it to, the phrase "a grantism".

The Japanese have a saying "the nail which sticks up must be hammered down", but I like to counter it with one of my own sayings; "up yours".

Go, Grant! (Run, Forest, run!)

At 5:34 pm, Blogger Dr Zen said...

I think you do not understand why Gunt has his comments deleted. You might consider that, with one exception--purely motivated by pity, I delete only spam.

There are no rules here, except those I make up on the fly in the eternal game of making the hours pass. That you think otherwise probably says more about you than it does about me or Gunt.

At 11:23 pm, Blogger Sopwith-Camel said...

Dr, I had passed on from that episode of the clobbered comment ages ago. I was delighted by Father Luke's choosing Grant as the subject for his comments on that of which we had been speaking, that is to say, which term should one use?

And I too have deleted a comment of Grant's on my own blog, simply because it also involved a reference to a second commenter who I felt obliged to offer some protection to.

I suspect that Grant loves trying to push the boundaries, and doesn't really mind being snipped. He might even have a scoreboard at home recording how many times he has been expunged from different blogs.

"He's a cunt, Jim, but not as we know it."

At 12:02 am, Anonymous Anonymous said...

The barking dog is in fact Ginger its his wife and she barks every time he goes near her.

At 12:06 am, Anonymous Anonymous said...

Many of my deleted comments related to his wife's motives for wanting to live in Brighton and the size and effectiveness of Dave's manhood.


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