Q: When you use “whether,” do you need “or not”? I find “whether” being used alone for “if,” and I wonder what is correct.
A: In the phrase “whether or not,” the “or not” is often optional. When the choice is up to you, you can generally use either “whether” or “if.”
But you definitely need “or not” when you mean “regardless of whether,” as in, “I’m out of here whether you like it or not!”
Pat discusses this in her grammar and usage book Woe Is I. Here’s the passage:
“When you’re talking about a choice between alternatives, use whether: Richie didn’t know whether he should wear the blue suit or the green one. The giveaway is the presence of or between the alternatives. But when there’s a whether or not choice (Richie wondered whether or not he should wear his green checked suit), you can usually drop the or not and use either whether or if: Richie wondered if [or whether] he should wear his green checked suit. You’ll need or not, however, if your meaning is ‘regardless of whether’: Richie wanted to wear the green one, whether it had a gravy stain or not. (Or, if you prefer, whether or not it had a gravy stain.)”
Merriam-Webster’s Dictionary of English Usage has some very good advice: “Of course, the simplest way to determine whether the or not can be omitted is to see if the sentence still makes sense without it.”
In case you’re interested, our word “whether” developed from the Old English term hwæther, meaning which of the two. (We’ve used “th” here to represent the letter thorn.)
The Old English term was derived from two prehistoric Germanic roots: khwa- or khwe- (source of such English words as “what” and “who”) and –theraz (a source of “other”), according to John Ayto’s Dictionary of Word Origins.
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