If or not
Both “if” and “whether” can introduce a subordinate clause: “I was wondering if you would come” and “I was wondering whether you would come”. However, the phrase “whether or not”, as in “I was wondering whether or not you would come” is okay, but “if or not” in the same context seems not okay - google searches bring up 100 million hits for the first phrase, but just 15,000 for the second. This came up in a class I was in, and I was surprised because I do use “if or not” in informal speech; why are these two phrases different? In both cases the “or not” is redundant, if you think about it.