Concept
In linguistics, a polarity item is a lexical item that is associated with affirmation or negation. An affirmation is a positive polarity item, abbreviated PPI or AFF. A negation is a negative polarity item, abbreviated NPI or NEG. The linguistic environment in which a polarity item appears is 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 particular type have the same licensing contexts. As examples of polarity items, consider the English lexical items somewhat and at all, as used in the following sentences: I liked the film somewhat. I didn't like the film at all. I liked the film at all. I didn't like the film somewhat. 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: I was going nowhere. (the negative nowhere is used when not preceded by another negative) I was not going anywhere. (the NPI anywhere is used in the environment of the preceding negative not) Note that double-negative constructions like I was not going nowhere take on an opposing meaning in formal usage, but that this is not necessarily the case in colloquial contexts and in various lects, which parallels other languages which have negative concord.