Is "not unpleasant" a double negative, and hence bad grammar? See the first answer (by Ham and Bacon) to this question, for the basis of this question:
"Did you enjoy the movie?"
"Well, I didn't not enjoy it, but..."
Are all "not un..." forms incorrect? They are very widely used, much more so than the blatant "not not" or "didn't not", etc.
There are two distinct meanings to the phrase "double negative":
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'.
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.
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.
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:
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:
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.
A double negative is not necessarily bad grammar. Double negating the same word, e.g. "not unpleasant" is ok to do. If you overdo it, or unnecessarily do it, it can be considered bad style.
It can however be grammatically incorrect to use double negation: E.g. it's not grammatical to negate both the verb and the noun of a sentence with the intention to negate the whole sentence: "We don't need no education", "I can't get no satisfaction", ... There are languages where this form of double negation is allowed (or even mandatory), but English is not one of them.
A double negative consists of two negatives, and what needs to be determined, is what is a negative?
A "negative" is a word that cancels out e.g. not, no, never, no one, etc..
It is not a prefix. N.B. That is why, "not unpleasant" is not a double negative.
“Not unpleasant” is not a double negative.
There is a whole range of how you could feel about some experience. “Pleasant” and “unpleasant” are just two ways, but they don’t cover the whole range. “Not unpleasant” is better than “unpleasant”, but not quite as good as “pleasant”. “Not unpleasant at all” would be even better.
