If or Whether?

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What Is the Difference between "If" and "Whether"?

"If" and "whether" are easy to confuse, and the rules on which to use can be complicated. However, here is a simple rule for "if" and "whether" that will keep you safe.

• Use "if" to introduce a condition. In all other circumstances, use "whether."
(This rule will see you right, but there are other options.)

Using "If" with a Condition

A condition is something that must be satisfied before something else occurs. For example (conditions shaded):

• If it rains, bring in the tables.
("If it rains" is a condition. This is called a conditional sentence.)
• Add a point if I get the right answer.
("If I get the right answer" is a condition. This is another example of a conditional sentence.)

More about "If" and "Whether"

The words "if" and "whether" are sometimes interchangeable. However, this is not always the case.

Whether and If (Interchangeable)

"Whether" and "if" can be used interchangeably in the following two circumstances:

(1) When reporting yes/no questions.

• I am unsure whether I will be attending the party.
• I am unsure if I will be attending the party.
(In this example, the yes/no question is "Am I attending the party?")

• Janice wondered whether she had unplugged the iron.
• Janice wondered if she had unplugged the iron.
(In this example, the yes/no question is "Did Janice unplug the iron?")

(2) In whether/if...or...constructions

• I would like to know whether it is a true story or fabricated.
• I would like to know if it is a true story or fabricated.
(Note: Using "whether" is far more common.  It is certainly more formal.)

Whether

In the following five circumstances, "whether" should be used:

(1) To present two alternatives (neither of which is a condition).

• Inform the clerk whether Mark needs a seat.
(In this example, the two alternatives are "Mark needs a seat" and "Mark does not need a seat." The clerk is to be informed in either case.)
• Inform the clerk if Mark needs a seat.
(This sentence is not grammatically wrong, but it does not mean the same as the first example. In this example, the clerk is only to be informed if Mark needs a seat. Therefore, Mark needing a seat is a condition. This is a conditional sentence. See the section on "If" below.)
• Let Anna know whether the boss is able to go to Crowborough.
(In this example, the two alternatives are "going" and "not going."  Anna needs to know the answer regardless of which is chosen.)
• Let Anna know if the boss is able to go to Crowborough.
(This sentence is not grammatically wrong, but it does not mean the same as the one above. In this example, Anna needs only to be told if the boss is going to Crowborough.)

(2) After prepositions.

• I would like to talk about whether you are going to California.
(The word "about" is a preposition.)
• At this point, the flight attendant makes the decision on whether the passenger stays on the aircraft.
(The word "on" is a preposition.)

(3) Before infinitive verbs starting "to" (e.g., whether to ask).

• I have been thinking whether to grow my own tomatoes this year.
("To grow" is an infinitive verb)

(4) When "whether" starts a clause that is the sentence subject or complement.

• Whether you sink or swim is not my concern.
("Whether you sink or swim" is the subject of this sentence.)
• I don't care whether you sink or swim.
("Whether you sink or swim" is the complement of the verb "to care.")

(5) In formal writing.

When "if" and "whether" are interchangeable, choose "whether" in formal writing.

• I doubt whether the team will succeed.
• Please establish a committee to determine whether the proposed funding lines are appropriate.

If

Use "if" to introduce a condition (i.e., in a conditional sentence). In a conditional sentence, a condition has to be satisfied before something occurs.

Example sentences with "if":

• If you sing, I'll pay you ten pounds.
• Peter will catch you if you fall.

The Phrase "Whether or Not"

When using the phrase "whether or not," the "or not" is often superfluous (i.e., not required). However, when "whether or not" means "regardless of whether," the "or not" part is required.

Example sentences with "whether or not":

• Reprimand Chris whether or not he is on time today.
("...regardless of whether he is on time today.")
• The parade will go ahead whether it rains or not.
("...regardless of whether it rains.")
(Note: There is leniency on where the "or not" is placed. It does not have to follow immediately after "whether.")

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