What constitutes a double negative?

Solution 1:

There are two distinct meanings to the phrase "double negative":

• one (which most people understand by it) is a particular prescriptive rule that applies specifically to Standard English, but not many dialects. As mentioned elsewhere it only refers to using 'no' or 'no-' when 'any or 'any-' is supposed to be used. For example,

I don't want nothing

is OK in nonstandard English but in Standard English it is:

I don't want anything

This is the only thing referred to when people say "don't use double negatives".

The pattern of multiple negation words used to express a single negation is called 'negative concord'.

• the other is 'more than one logically intended negative'. This is perfectly grammatical in -all- dialects but, because of the semantic depth/cognitive processing limitations, is often hard to understand. For example,

I can't not be pleased at your compliment.

means the negation of the negation of the ability to be pleased, from which it follows literally that it is possible to be pleased.

Whether or not explicit negation words are used, the logical content has a depth of at least two negations. These can sound wrong because of the difficulty in processing but is well-formed syntactically and semantically coherent.

I don't deny the impossibility of regret from no lack of silence.

This is perfectly grammatical and it has a specific calculable meaning.

Solution 2:

In your example, not unpleasant doesn't mean unpleasant, and it's not a double negative used to express a negative statement. It's a double negative that is used to express a positive statement, and it can be used for rhetorical effect, or to put emphasis.

There is not nothing to worry about!

I can't get no satisfaction.

The NOAD has a note about double negatives.

According to standard English grammar, a double negative used to express a single negative, such as "I don't know nothing" (rather than "I don't know anything"), is incorrect. The rules dictate that the two negative elements cancel each other out to give an affirmative statement, so that, logically, "I don't know nothing" means "I know something." In practice, this sort of double negative is widespread in dialect and nonstandard usage and rarely causes confusion about the intended meaning. Double negatives are standard in other languages such as Spanish and Polish, and they have not always been unacceptable in English. It was normal in Old English and Middle English and did not come to be frowned upon until some time after the 16th century. The double negative can be used in speech or in written dialogue for emphasis or other rhetorical effects. Such constructions as 'has not gone unnoticed' or 'not wholly unpersuasive' may be useful for making a point through understatement, but the double negative should be used judiciously because it may cause confusion or annoy the reader.

Solution 3:

What constitutes a double negative is in theory quite simple: it is any pair of negative words that modify the same sentence or clause.

The only problem is which words to count as negatives. Words like never, hardly, unpleasant, and immoral are commonly considered negatives. (Whether you consider the whole word unpleasant a negative or just the prefix un- would not seem a very interesting question.) Other words are disputed, like bad, atheist, and reject.

In some cases the words any, ever, and either can be added as a test, because it is used when a speaker has something negative at the back of his mind, as opposed to neutral some:

There's hardly any fungus left. What am I to eat now?

? There's hardly some fungus left. What am I to eat now?

The first sentence is vastly more common, because hardly is normally a negative. But this test doesn't always work (how to apply it to immoral?), and so we cannot use it to establish clear boundaries.

She rejected any proposal he dared show her.

She rejected this proposal he dared show her.

It seems reject is a negative when used with any, but not so with other words.

However that may be, it is usually not important whether we call two words "double negatives" or just a negative and some other word: in both cases there can be litotes, as long as the first word changes the meaning of them both into the opposite of the second word:

• Not bad is the opposite of good.
• That building is not very high: this indicates the opposite, low.

It is a candidate for litotes as long as both words together immediately conjure up another word (good) that is the opposite of the second word (bad). This is not the case with any word at random:

• This book is not yellow: then what is it? Blue? Magenta?

But in certain situations, where yellow and not yellow are the only two relevant categories, they may even constitute litotes too.

Shh, don't ever mention her hair. She is only thirty; but it is, you know, not black, despite appearances.