In linguistics, a polarity item is a lexical unit that can appear only in the environment of a certain “licensing context.” Polarity items are defined as Negative Polarity Items (NPIs) or Positive Polarity items (PPIs). Simple negation creates a licensing context for most NPIs, while affirmative statements license most PPIs.
To illustrate, consider these sentences using NPIs at all or any.
- I didn't like the film at all
- *I liked the film at all
- John doesn't have any potatoes
- *John has any potatoes.
In both pairs, the NPIs are licensed by negation. To illustrate a PPI, consider the word somewhat in the following pair:
- John liked it somewhat.
- *John didn't like it somewhat.
Somewhat is licensed by the affirmative environment, but it is forbidden (anti-licensed) by the negative environment (Baker 1970). Baker also noticed that double negation may provide an acceptable context for positive polarity items:
- I can't believe you don't fancy her somewhat.
However, licensing contexts can take many forms besides simple negation/affirmation. To complicate matters, polarity items appear to be highly idiosyncratic, each with its own set of licensing contexts.
Early discussion of polarity items can be found in the work of Otto Jespersen and Edward Klima. Much of the research on polarity items has centered around the question of what creates a negative context. In the late 1970-s, William Ladusaw (building on work by Gilles Fauconnier) discovered that most English NPIs are licensed in downward entailing environments. This is known as the Fauconnier–Ladusaw hypothesis. A downward entailing environment, however, is not a necessary condition for an NPI to be licensed — they may be licensed by some non-monotone (and thus not downward entailing) contexts, like “exactly N”, as well.
- *Some people have ever been on the moon.
- Exactly three people have ever been on the moon.
Nor is a downward entailing environment a sufficient condition for all negative polarity items, as first pointed out by Zwarts (1981) for Dutch “ook maar”.
Licensing contexts across languages include the scope of n-words (negative particles, negative quantifiers), the antecedent of conditionals, questions, the restrictor of universal quantifiers, non-affirmative verbs (doubt), adversative predicates (be surprised), negative conjunctions (without), comparatives and superlatives, too-phrases, negative predicates (unlikely), some subjunctive complements, some disjunctions, imperatives, and others (finally, only). Given this wide range of mostly non-downward entailing environments, the Fauconnier-Ladusaw Hypothesis has gradually been replaced in favor of theories based on the notion of nonveridicality (proposed by Zwarts and Giannakidou).
Different NPIs may be licensed by different expressions. Thus, while the NPI anything is licensed by the downward entailing expression at most two of the visitors, the idiomatic NPI lift a finger (known as a “minimizer”) is not licensed by the same expression.
- At most two of the visitors had seen anything.
- *At most two of the visitors lifted a finger to help.
While NPIs have been discovered in many languages, their distribution is subject to substantial cross-linguistic variation; this aspect of NPIs is currently the subject of ongoing research in cross-linguistic semantics.
Famous quotes containing the words polarity and/or item:
“The same polarity of the male and female principle exists in nature; not only, as is obvious in animals and plants, but in the polarity of the two fundamental functions, that of receiving and penetrating. It is the polarity of earth and rain, of the river and the ocean, of night and day, of darkness and light, of matter and spirit.”
—Erich Fromm (1900–1980)
“Those things for which the most money is demanded are never the things which the student most wants. Tuition, for instance, is an important item in the term bill, while for the far more valuable education which he gets by associating with the most cultivated of his contemporaries no charge is made.”
—Henry David Thoreau (1817–1862)