My post yesterday about “Whether” vs. “If” reminded me about “Whether or not”.

Problem:
Some people use “whether or not” when “whether” is appropriate (and complete!).

Explanation:
It is overkill to include “or not” in sentences such as “He will not say whether or not he wants to leave the company.” This example can be correctly rewritten as “He will not say whether he wants to leave the company.”

In this example, the conjunction “whether” introduces a clause whose uncertainty is unknown. Adding “or not” after “whether” adds no value in such situations. One could say that adding “or not” introduces unnecessary redundancy.

There is a valid use for including “or not” somewhere in a “whether” sentence: when one wants to say “regardless of whether” or “no matter whether”.

For example, both of these sentences contain “whether” and “or not” and are valid:

• “We must depart for the train station in one hour whether or not you have found your swimsuit.”
• “We must depart for the train station in one hour whether you have found your swimsuit or not.”

Either of the above two sentences is a valid substitute for either of the following two sentences:

• “We must depart for the train station in one hour regardless of whether you have found your swimsuit.”
• “We must depart for the train station in one hour no matter whether you have found your swimsuit.”

I believe that the use of “whether or not” in speech as a substitute for “regardless of whether” or “no matter whether” supports my “Devolution toward Simpler” hypothesis. It’s simpler to say “whether or not” (four syllables) than to say “regardless of whether” (six syllables) or “no matter whether” (five syllables).

Solution:
Use “whether” to introduce a clause whose certainty is unknown. Use “whether or not” in speech as a substitute for “regardless of whether” or “no matter whether”; otherwise, avoid using “whether or not”.