Using "Whether" or "Whether or not"

Question

I read the information about using whether or whether or not on your web site; however, I am still not certain about making the choice. Could you please tell me the specific rules for using whether or whether or not?

Is this sentence okay?

You can go whether or not you finished your homework.

Answer 1

Bryan Garner, Garner's Modern American Usage, second edition (2003) answers this question in a consistent way that is easy to apply to particular instances of "whether (or not)":

Whether or not. Despite the superstition to the contrary, the words or not are usually superfluous, since whether implies or not—e.g.,:

• "In another essay, 'The Rules of the Game,' he discusses moral codes and whether or not {read whether} they work." Diane Hartman, "At Life's End Carl Sagan Awed by Life's Unknowns," Denver Post, 22 June 1997, at D6. [Other examples—involving "deciding whether (or not)" and "decide whether (or not)"—omitted.]

But the or not is necessary when whether or not means"regardless of whether" {the meeting will go on whether or not it rains}. [Other examples omitted.]

By Garner's reasoning, you don't need or not in this sentence:

You can decide whether to go once you've finished your homework.

but you do need it in your original sentence:

You can go whether or not you finished your homework.

Answer 2

Usually when using the word whether in a sentence, the or not is superfluous (i.e., not required). However, when whether or not means regardless of whether, the or not part is required.

Examples of when or not is required:

• The postman will deliver my mail today whether it snows or not.
  • (…regardless of whether it snows.)
• The former CEO of Global Bank is going to jail today whether or not he is actually innocent.
  • (…regardless of whether he is actually innocent.)

Note: The or not does not have to follow immediately after whether, so there is some leniency on where it is placed.