Double negation: unless followed by a negative verb form?

Question

We will not cancel the game if the weather gets better. Replacing "if" with "unless", you end up with either: "We will cancel the game unless the weather gets better." or "We will **not** cancel the game **unless** the weather does **not** get better." Is the latter sentence an absolute no-no? Or even a no-no-no!

Answer 1

The latter sentence is correct! Let's look at each of your three sentences and the ideas that they represent...

1) "We will not cancel the game if the weather gets better."

Weather conditions improve = game is played. [Current weather conditions persist = game is canceled.]

The tone is neutral.

2) "We will cancel the game unless the weather gets better."

Current weather conditions persist = game is canceled. Weather conditions improve = game is played.

Expectation: they will probably cancel the game. The tone is pessimistic.

3) "We will not cancel the game unless the weather does not get better."

Current weather conditions persist = game is canceled.

Expectation: we will not cancel the game. Expectation: the weather will get better. The tone is optimistic.

All three of your sentences are grammatically correct. The ideas conveyed are very similar. The only difference is what is implied or emphasized by the difference in tone. I hope this helps!

N.B. In spoken English, contractions would probably be used. "We won't cancel the game unless the weather doesn't improve."