Negative polarity

In linguistics, a polarity item is a lexical item that can appear only in environments associated with a particular grammatical polarity – affirmative or negative. A polarity item that appears in affirmative (positive) contexts is called a positive polarity item (PPI), and one that appears in negative contexts is a negative polarity item (NPI).

The environment in which a polarity item is permitted to appear is called a "licensing context". In the simplest case, an affirmative statement provides a licensing context for a PPI, while negation provides a licensing context for an NPI. However, there are many complications, and not all polarity items of a given type need necessarily have exactly the same set of licensing contexts.

As examples of polarity items, consider the English lexical items somewhat and at all, as used in the following sentences:

As can be seen, somewhat is licensed by the affirmative environment of sentence (1), but it is forbidden (anti-licensed) by the negative environment of sentence (4). It can therefore be considered to be a positive polarity item (PPI). On the other hand, at all is licensed by the negative environment of sentence (2), but anti-licensed by the positive environment of sentence (3), and is therefore considered a negative polarity item (NPI).

Because standard English does not have negative concord, that is, double negatives are not used to intensify each other, the language makes frequent use of certain NPIs that correspond in meaning to negative items, and can be used in the environment of another negative. For example, anywhere is an NPI corresponding to the negative nowhere, as used in the following sentences:

Note that the alternative form with the double negative, *I was not going nowhere, is ungrammatical in the standard language, although such forms are used in some colloquial English, and parallel the constructions used in certain other languages which have negative concord. (Note also that anywhere, like most of the other NPIs listed below, is also used in other senses where it is not an NPI, as in I would go anywhere with you.) Similar pairs of negatives and corresponding NPI are listed below.

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