Possible Duplicate:
When is it appropriate to use 'that' as opposed to 'which'?

From what I understand the second sentence is correct, and the first is not. What are the rules on using which versus using that?

  1. Instead it produces the above, which simply is a silent error.
  2. Instead it produces the above, that is simply a silent error.

marked as duplicate by Cerberus, F'x, RegDwigнt Mar 7 '11 at 13:11

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The notes about when to use which and that reported from the NOAD are the following:

In U.S. English, it is usually recommended that which be employed only for nonrestrictive (or nonessential) clauses: the horse, which is in the paddock, is six years old. (The which clause contains a nonessential fact, noted in passing; the horse would be six years old wherever it was.) A that clause is restrictive (or essential), as it identifies a particular thing: the horse that is in the paddock is six years old (not any horse, but the one in the paddock).

To notice that (in sentences similar to the ones you used as example) which is generally preceded by a comma, and that is generally not preceded by a comma.

  • 2
    As a prescriptive rule, this may be true (especially if by "usually recommended" you read "advocated by Microsoft Word's spellchecker"). In actual practice, use of the type "the horse which is in the paddock" (where 'which' and 'that' are essentially interchangeable) seems to be widespread and well accepted. – Neil Coffey Feb 19 '11 at 0:12

Only "which" is grammatical in this case.

In general, "that" is not used in a non-restrictive relative clause like this (where in effect, the relative clause adds 'additional information' about the referent but doesn't serve to identify the referent).


Any of the above, which constitutes an error, should be removed.

Any of the above that constitutes an error should be removed.

The first case means "the whole of the above constitutes an error and should be removed"; the second implies "those parts of the material above which are erroneous should be removed, but other parts may remain".

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