Weighing in on whether: Discussions are going on at the ACES board and at Stylin' and Smilin' about when it's OK to drop "or not" from the phrase "whether or not."

My thoughts? I posted this to the ACES board:

I disagree that "or not" can always be omitted. Sometimes the omission sounds plain wrong.

The New York Times style manual explains it nicely:

"When a 'whether' clause modifies a verb, 'or not' is needed: They will play tomorrow whether or not it rains. (The clause modifies play.)"

Bremner's "Words on Words" points out another exception:

"Sometimes, however, 'or not' is needed to stress the altenative, as in 'I'll love you whether or not you leave me.' To decide whether 'or not' is needed, substitute 'if' for 'whether.' If the substitution changes the meaning, 'or not' is needed. 'I'll love you if you leave me' is decidedly different from 'I'll love you whether or not you leave me.'