predicate premise propositions

In grammar, the predicate of a sentence makes the assertion about the subject, and comprises a finite verb (required), with or without other related words. Thus, the predicate comprises any part of the sentence that is not a part of the subject, but that provides information about the subject.

In logic, a premise is a statement or assertion that forms the basis for a rationale, approach, or position. Thus, a premise is a proposition that is offered in support of the truth of the conclusion (another proposition) in an argument. A premise of an argument is assumed to be true, though it may in practice be false in arguments that lack validity. The argument proceeds from the premise or premises to the conclusion, and a cogent argument proceeds logically from premise/s to conclusion. Critical thinking aims to discern the cogency and validity of arguments by assessing the acceptability of premises, the logic by which the arguments moves from premise/s to conclusion, and the validity of the conclusion.

In logic, a proposition is a statement, couched as a declarative sentence, that affirms or denies the predicate, and that is either true or false. In logical positivism, propositions are often related to closed sentences, distinguishing them from the content of an open sentence (predicate). Propositions comprise the content of assertions, and are sometimes expressed as non-linguistic abstractions derived from the linguistic sentence that constitutes an assertion. Because propositions can have different functions (names, predicates and logical constants), the nature of propositions is a subject of debate amongst philosophers. Many logicians prefer to use sentences and to avoid use of the term proposition.

"We say that a sentence is factually significant to any given person, if and only if, he knows how to verify the proposition which it purports to express-that is, if he knows what observations would lead him, under certain conditions, to accept the proposition as being true, or reject is as being false."

~ A. J. Ayer

Quo Vadis?
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a priori vs a posteriori

In epistemology, a priori propositions can be known independent of (prior to) experience, whereas a posteriori propositions can be known only on the basis of experience (after experience). Thus, the distinction between a priori and a posteriori corresponds roughly to the distinction between nonempirical and empirical knowledge.

The a priori/a posteriori distinction is applied to ways of knowing, propositions, arguments, and concepts. Because of its dependence upon verification by experience, the foundation for classifying a proposition's as a posteriori is more easily grasped. An a priori concept can be acquired independently of experience, which may include, but is not necessarily confined to innate concepts.

The term 'justification' signifies that the person who believes something has an epistemic reason to thinking that the belief is true. So, to be a priori justified in believing a given proposition is to have a reason independent of experience for thinking that the proposition is true. Such propositions include simple perceptual, numerical, and logical relations – ice water is cooler than boiling water, blue is a colour, three plus two is five, when comparing two men the taller man is not shorter than the shorter man. One is a priori justified in believing a given proposition if, on the basis of pure thought or reason, one has a reason to consider the proposition to be true.

Quo Vadis?
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