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In modern logic, a proposition or ansatz is what is
asserted as the result of uttering a sentence. In other words, it is the meaning of
the sentence, rather than the sentence itself. Different sentences can express the same proposition, if they have the same
meaning. Sometimes one says that a proposition is what is expressed by a closed sentence, to distinguish it from
what is expressed by an open sentence, or predicate.
Whether propositions are real entities, and if so of what sort (e.g., Platonic abstracta), is a matter of philosophical
dispute.
In Aristotelian logic a proposition is a
particular kind of sentence, one which affirms or denies a predicate of a
subject, and thus asserts something true or false. Propositions fall unto three
classes. Universal
propositions, such as "all men are mortal" affirm or deny the predicate mortal of the "whole of" their subject, i.e. the
entire class of things that the subject applies to. Particular propositions, such as "some men are mortal" affirm or deny the
predicate of only part of the subject. Singular propositions, such as "Socrates is a man" present a difficulty. Usually they were regarded as
a universal proposition, since they can only be true of a single object, and thus true of all the objects (one) they possibly can
be true of. On the other hand, "they are in truth the most limited kind of particular propositions".
See also: symbolic logic, truthmaker
In many U.S. states, a proposition is a ballot measure
consisting of a statute or constitutional amendment "proposed" to the voters for their approval. It can take the form of an
initiative or referendum. For
example, see the list of
California ballot propositions.
Proposition is also a name given, in debates, to the team which
supports and tries to prove a motion.
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