open formula also called open sentence, a sentence with a free occurrence...

open loop See CYBERNETICS.

open question argument See MOORE.

open sentence See OPEN FORMULA.

open society See POPPER. open texture, the possibility of vagueness. Friedrich Waismann...

operant conditioning See CONDITIONING.

operational definition See OPERATIONALISM.

operationalism a program in philosophy of science that aims to interpret...

operator a one-place sentential connective; i.e., an expression that may be...

operator, deontic See DEONTIC LOGIC.

operator, propositional See SENTENTIAL CONNEC -. TIV.

operator, scope of See AMBIGUITY, SCOPE.

operator, sentential See SENTENTIAL CONNECTIVE.

operator theory of adverbs a theory that treats adverbs and other predicate modifiers as...

O-proposition See SYLLOGISM.

oratio obliqua See INDIRECT DISCOURSE.

order the level of a logic as determined by the type...

ordered n-tuple See SET THEORY.

ordered pair See SET THEORY. ordering, an arrangement of the elements of...

ordering, Archimedian See LEXICAL ORDERING.

order type omega in mathematics, the order type of the infinite set of...

ordinal logic any means of associating effectively and uniformly a logic (in...

ordinal utility See UTILITARIANISM.

ordinary language philosophy a loosely structured philosophical movement holding that the significance of...

organic having parts that are organized and interrelated in a way...

organicism a theory that applies the notion of an organic unity,...

organic unity See ORGANIC.

organism a carbon-based living thing or substance, e.g., a paramecium, a...

Organon See ARISTOTLE.

Origen (A.D. 185–253), Christian theologian and biblical scholar in the Alexandrian...