‘Whether’ or ‘whether or not’?

Blog reader Helen asks:

Can I have some advice on how to use ‘whether’? As in ‘whether to write something’ or ‘whether or not to write something’. Leaving out ‘or not’ feels incomplete but putting it in feels unwieldy and unnecessary.

You can test this by asking yourself if the use of ‘or not’ serves a function within the sentence. In the above example, the ‘or not’ is superfluous – unless you intend to give equal stress to the alternative.