Handling Negatives – Not . . . But . . .

Once again the two elements should be grammatically symmetrical:
We shall fly not the green flag but the blue one. We shall not fly the green flag but display the blue one.
In colloquial idiom, these two structures are mixed:
? We shall not fly the green flag but the blue one.
Avoid such imbalance, expecially in formal writing. Take care, however, not to let ambiguity creep in when you balance the construction:
? The new militancy presents a danger to democracy. It is trying not to make a point but to deny a hearing.
The intended meaning here is surely not trying to make a point but actual wording, for the sake of symmetry, has been twisted into trying not to make a point. Only a fairly drastic rephrasing will resolve the problem: It is not trying to make a point – it is trying to deny a hearing.

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