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'If' Versus 'Whether'

Sometimes if and whether are interchangeable, but sometimes using one or the other will change the meaning of your sentence. Here are some examples and an explanation.

By
Mignon Fogarty
3-minute read
Episode #457

Today's topic is whether—not rain or snow, but whether w-h-e-t-h-e-r, as in whether you like it or not, it's the topic.

First, let's figure out when to use whether and when to use if.

If Versus Whether

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Although in informal writing and speech the two words are often used interchangeably, in formal writing, such as in technical writing at work, it's a good idea to make a distinction between them because the meaning can sometimes be different depending on which word you use. The formal rule is to use if when you have a conditional sentence and whether when you are showing that two alternatives are possible. Some examples will make this more clear.

Here's an example where the two words could be interchangeable:

Squiggly didn't know whether Aardvark would arrive on Friday.

Squiggly didn't know if Aardvark would arrive on Friday.

In either sentence, the meaning is that Aardvark may or may not arrive on Friday.

Now, here are some examples where the words are not interchangeable:

Squiggly didn't know whether Aardvark would arrive on Friday or Saturday.

Because I used whether, you know that there are two possibilities: Aardvark will arrive on Friday or Aardvark will arrive on Saturday.

Now see how the sentence has a different meaning when I use if instead of whether:

Squiggly didn't know if Aardvark would arrive on Friday or Saturday.

Now in addition to arriving on Friday or Saturday, it's possible that Aardvark may not arrive at all. These last two sentences show why it is better to use whether when you have two possibilities, and that is why I recommend using whether instead of if when you have two possibilities, even when the meaning wouldn't change if you use if. It's safer and more consistent.

Here's a final pair of examples:

Call Squiggly if you are going to arrive on Friday.

Call Squiggly whether or not you are going to arrive on Friday.

The first sentence is conditional. Call Squiggly if you are going to arrive on Friday means Aardvark only needs to call if he is coming.

The second sentence is not conditional. Call Squiggly whether or not you are going to arrive on Friday means Aardvark needs to call either way.

To sum up, use whether when you have two discrete choices or mean "regardless of whether," and use if for conditional sentences.

Next: Whether Versus Whether or Not

Whether Versus Whether or Not

That last example is also a good lead in to our second topic: When do you need an or not after whether? Why did I say, "Call Squiggly whether or not you are going to arrive on Friday?"

Often, the or not is just extra fluff and should be left off. In my first example, where I said, "Squiggly didn't know whether Aardvark would arrive on Friday," adding an or not wouldn't change the meaning or emphasis. Squiggly didn't know whether or not Aardvark would arrive on Friday means the same thing as Squiggly didn't know whether Aardvark would arrive on Friday. Or not is superfluous, so leave it out.

On the other hand, you need the full phrase whether or not when you mean "regardless of whether." It shows that there is equal emphasis on both options.

Call Squiggly regardless of whether you are going to arrive on Friday.

Call Squiggly whether or not you are going to arrive on Friday.

Finally, a listener wrote to say that her boss was driving her crazy by saying "rather or not" instead of "whether or not." So I'll add that rather or not is incorrect; whether is a conjunction and rather is an adverb, and they are not interchangeable. Whether or not is the correct way to show that there are two possibilities or you mean "regardless of whether."

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Using the wrong word can change the meaning of your sentence! Use "if" in conditional sentences and "whether" when writing about two alternatives.

References

Bernstein, T.M. Do's Don'ts and Maybes of English Usage, Times Books: New York. 1977, p.237.

Garner, B. Garner's Modern American Usage, third edition.. Oxford: Oxford University Press. 2009, p. 689.

if. American Heritage College Dictionary. Fourth Edition. Houghton Mifflin Company:Boston. 2007, p. 689.

rather. Dictionary.com. Dictionary.com Unabridged (v 1.1). Random House, Inc. http://dictionary.reference.com/browse/rather (accessed: May 23, 2008).

Kilian, C. "Rather? Whether?" Ask the English Teacher. May 26, 2006. http://crofsblogs.typepad.com/english/2006/05/rather_whether.html (accessed: May 23, 2008).

whether. Dictionary.com. Dictionary.com Unabridged (v 1.1). Random House, Inc. http://dictionary.reference.com/browse/whether (accessed: May 23, 2008).

About the Author

Mignon Fogarty

Mignon Fogarty is the founder of Quick and Dirty Tips and the author of seven books on language, including the New York Times bestseller "Grammar Girl's Quick and Dirty Tips for Better Writing." She is an inductee in the Podcasting Hall of Fame, and the show is a five-time winner of Best Education Podcast in the Podcast Awards. She has appeared as a guest expert on the Oprah Winfrey Show and the Today Show. Her popular LinkedIn Learning courses help people write better to communicate better.