-
Double/Triple Negatives
There are no rules about whether there should be only a single negative or if multiple negatives are acceptable. However, for the sake of clarity, it should be avoided in certain circumstances. For example:
He/She hasn't done nothing — This usage should be avoided even if certain phrases like "ain't nobody got time for that" are understood from context; not everyone will be aware of what is meant just because most other people do.
-
Wouldn't you not like to have a drink? — This usage is acceptable because it is an indirect and very formal way of making a request. In this case, it is the same as saying "Would you like to have a drink?" which is more direct and casual but may sound forceful in formal situations. To rephrase this double negative, think of it like: "would you not like it, to not have a drink?".
Both "Wouldn't you like to have a drink?" and "Wouldn't you not like to have a drink?" are the same; there is no change in meaning. The double negative does not cancel anything out. Many textbooks, teachers or style guides will discourage this as ambiguous or a grammatical error. This is not a grammatical error nor does ambiguity define a grammatical error.
This double negative works best for making requests that are very formal. It mainly comes from old English where double negatives are generally used for consistency rather than mixing negative and positive statements together.
Neither this nor that — This usage is acceptable. As the above, this is simply for consistency and dates as far back as old English. The double negative does not cancel anything out.