There’s an old “rule” about “if” and “whether.” It says, basically, that “if” is for conditional clauses and “whether” is for situations in which two alternatives are possible.
“If you go to the store, get orange juice.”
“I don’t know whether it will rain.”
Obviously, those are both correct. But there’s one thing I don’t understand: Why did someone try make a rule about these words? Someone, at some point, looked at two sentences like these and said, “Hmm. I see these two terms are similar, yet different. I’d better lay down a law immediately before I have a chance to think about it.”
The fussing started all the way back in 1762 when J. Johnson published his “New Royal and Universal English Dictionary” and slapped 20 pages’ worth of grammar instruction up front. One of these instructions was that after a verb like “question,” “see” or “know,” you can’t use “if” and you must use “whether.”
So “I don’t know whether it will rain” is right and “I don’t know if it will rain” is wrong, according to Johnson.
That’s just not true. But the idea had some staying power. A century later, Alfred Ayers ran with it in the 1881 “The Verbalist.” Others followed.
English writers and speakers were better off without these experts’ help. There’s virtually no danger a native speaker or writer will mess up “whether,” for example by using it in place of “if” in a conditional sentence: “Whether you go to the store, get orange juice.” We don’t need to be told that doesn’t work.
As for those sentences that lay out two alternatives, “if” often works as well as “whether.”
“I don’t know whether he will attend.”
“I don’t know if he will attend.”
That second version is condemned by prescriptivists like Johnson and Ayers. But in fact it isn’t wrong at all. It’s a valid choice. And on this matter, native speakers don’t need help making a good choice. Just go with your ear.
The only real pitfall involving “if” and “whether” is illustrated by the following examples.
“I’m not sure whether Carrie will visit on Monday or Tuesday.”
“I’m not sure if Carrie will visit on Monday or Tuesday.”
In the first, we know Carrie will visit. We just don’t know which day.
But when you replace “whether” with “if,” as we did in the second example, the sentence is no longer clear. It’s possible that the day of her arrival is the question. But it’s also possible that Carrie may not come at all. Unlike the conjunction “whether,” which indicates there are two possibilities, “if” conveys a general uncertainty that could apply to either the timing of her arrival or the fact of her arrival.
Still, the only rule needed here is “Pay attention to what your words mean.”
Of course, no discussion of “whether” is complete without talking about whether or not you should add “or not.”
The short answer is: probably not. The word “whether” usually makes it plenty clear that there’s an “or not” option. Fewer words usually makes for a better reader experience. In professional editing, economy of words is a virtue. But sometimes you may find that it’s worth two extra words to emphasize that there are two possibilities. That’s fine.
You don’t have to take my word for it. Here’s what Merriam-Webster’s Dictionary of English Usage says about “whether or not”: “It is, in short, perfectly good idiomatic English.”
- June Casagrande is the author of “The Best Punctuation Book, Period.” She can be reached at JuneTCN@aol.com.