The language of possibility and probability: effects of negation on meaning.

Abstract

Modal adjectives (e.g., “possible” and “probable”) have been the subject of much discussion by linguists and logicians. For ordinary speakers, it was found that an important aspect of the meaning of modal adjectives is that they can all be used to qualify the truth of a statement: Subjects sorted modal adjectives according to similarity of meaning and then ordered the same adjectives solely according to their degree of qualification. The sorting data yielded a one-dimensional scaling solution of low stress that correlated highly with the results from the ordering task. Using the same techniques, negation was found to translate a modal adjective down the scale of qualification (e.g., “improbable” is more qualifying than “probable”) so that the order of affirmative adjectives with respect to each other is preserved for the corresponding negated adjectives. Negation in this domain is more analogous to a subtractive, rather than multiplicative, process. Also, affixal negation, as in “improbable” was consistently found to be more qualifying than lexical negation, as in “not probable.