• This will depend on whether he's suitable for the job.
    • This will depend on whether he's suitable for the job or not.
    • This will depend on whether or not he's suitable for the job.
    • It is still not defined whether we're following that approach.
    • It is still not defined whether we're following that approach or not.
    • It is still not defined whether or not we're following that approach.

"Or not" doesn't really seem to be needed to complement "whether". Why do people use it then? Is it redundancy and nothing more? Or is it for emphasis? Or are there cases when "or not" is required for the sentence to be grammatical?

  • 2
    As Henry Higgins observed in Pygmallion, the best grammarians are often those who learned English in school as immigrants. My parents, who were first-generation Americans in the early 20th century, learned English grammar in NYC public schools meticulously. They insisted "whether or not" is proper usage, period. Over time, language evolves or erodes and the rules change, which really means there are no authorities. I believe many changes are driven by relatively poorly educated TV personalities misusing words, which then become common usage. Someone once said, "C students rule the world." – user52936 Sep 27 '13 at 13:03
  • I think also that the phrase "or not" allows a sentence to end on an iamb. Might be useful if a writer cares particularly about his or her cadence. – ktm5124 Mar 3 '17 at 8:41
up vote 36 down vote accepted

The addition of the "or not" is neither logically nor grammatically required. I think it's often used conversationally for emphasis. I definitely wouldn't use it in writing myself.

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    The "If/*whether you decide to come, give me a call." example given in an answer to a strongly related question makes me question this pronouncement. I would hope some logical or grammatical rule would prevent the "Whether you decide to come, give me a call." option in such a case, even though I can't cite a specific rule myself. – John Tobler Sep 19 '11 at 22:36
  • Could you give me your thoughts on my answer? I'd be interested in hearing what you have to say about it. – timothymh Jul 2 '12 at 2:34
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    @JohnT I think whether emphasizes a dichotomy in which one option is imminent, though the option may not be known. If emphasizes the conditional nature of the matter. – fredsbend Mar 3 '14 at 16:00
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    Do you disagree with the rule WBT gave, from Garner, that "whether or not" is required in sentences like "Whether he shows up or not, we're getting started tomorrow"? Surely we can't say "Whether he shows up, we're getting started tomorrow"? – sumelic Jan 11 '17 at 7:00
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    Hopefully @b.roth can come by and change the 'approved' answer. It should be WBT's or FumbleFingers's. This one is certainly incomplete, omitting the origin of the use in its binary meaning. It's certainly sometimes still necessary. – lly Jul 6 '17 at 15:06

It's worth pointing out that, etymologically speaking, the roots of whether are which/either of two. It's inherently a "binary choice" word, so whereas "I don't know whether it be fish or fowl" is fine, "I don't know whether it be fish or fowl or good red herring" isn't really grammatical. Which is not to say people never use that extended form - but it does sometimes attract criticism.

With "unary choice" forms such as "I don't know whether I like it", the alternative ("I don't like it") can invariably be shortened to "or not" - or simply discarded completely, since it's implicit anyway.

Possibly some will say if only one choice is presented, you should use "if" rather than "whether", but skimming through written instances of "Tell me whether" suggests that most people have always been quite relaxed on that point.

TL;DR: "or not" is never required if the alternative is a simple negation of the stated proposition, but an "or" clause is required in, say, "You must choose whether to write novels or poems" (presupposing that writing, for example, software is not an option currently on offer).

The New York Times' stylebook says or not is often redundant.
It is ordinarily omitted when the clause functions as a noun, e.g. it is the object of a verb or preposition, or subject of the sentence.
However, when a whether clause acts as an adverb, or not is needed.
Check this NYT blog post for more details.

Another test, courtesy of Garner’s Modern American Usage: “or not” is necessary when the phrase “whether or not” means “regardless of whether.”

Similarly to tomothymh, I use "whether" alone unless I intend to convey "regardless of whather." In the latter case, I think "whether or not" is generally preferable to "regardless of whether."

Thus:

Whether I wear a coat depends on the temperature.

But:

I'm going to wear my new red coat whether or not it's cold.

When whether or not is implicit, you may use "or not" for the style or to underline ; it's up to you.

But if, "or not" is not implicit - for ex. in a choice with options, we don't use "or not" : "Whether the car will be black, red or white, I shall drive it."

I'm surprised nobody mentioned this that I saw, so I'll post an answer.

The word whether should be used by itself in the situations you mentioned above. The “or not” is a mistaken crossover from the correct usage of “whether or not” mentioned below. It is often used that way, but when writing it's best to avoid that unnecessary bit.

The phrase whether or not is a condition, used in statements to show that something will or will not happen, regardless of certain other variables:

I'm going to go on strike whether or not anyone joins me!

This would be less correct, however, if used like this:

I don't care whether or not anyone joins me, I'm going on strike!

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    I don't see any difference in meaning or grammaticality of your two examples. – Mr. Shiny and New 安宇 Jul 2 '12 at 4:01
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    That's my point exactly—the meaning is exactly the same. However, if you try removing "or not" from each of those, only one makes sense! – timothymh Jul 2 '12 at 4:24
  • My argument is a Strunk & White kind of one. – timothymh Jul 2 '12 at 4:25
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    I don't agree that the addition of or not is a "mistaken crossover". Whether introduces two or more possibilities; adding or not is merely clarifying what one of the possibilities is, whether or not it's obvious. ;-) – Jez Jul 2 '12 at 10:12
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    To quote Rule 17 of The Elements of Style: "Omit needless words." – timothymh Jul 2 '12 at 17:47

Although perhaps implied in the answers above, I think it could be clarified a bit: Whether is binary. In a sentence where two options are offered, no 'or not' is required - in fact it would be quite cumbersome. However, if the option is to do or not to do, is or isn't, then the 'or not' is required.

I don't know whether I should have the fish or the chicken. I don't know whether I should eat or not.

protected by tchrist Jul 1 '14 at 1:09

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