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A claim is a substantive statement about a thing, such as an idea, event, individual, or belief. Its truth or falsity is open to debate. Its truth or falsity is open to debate. Arguments or beliefs may be offered in support, and criticisms and challenges of affirming contentions may be offered in rebuttal.
Propositional logic deals with statements, which are defined as declarative sentences having truth value. [29] [1] Examples of statements might include: Wikipedia is a free online encyclopedia that anyone can edit. London is the capital of England. All Wikipedia editors speak at least three languages.
In formal logic, the statement "If today is Saturday, then 1+1=2" is true. However, '1+1=2' is true regardless of the content of the antecedent; a causal or meaningful relation is not required. The statement as a whole must be true, because 1+1=2 cannot be false. (If it could, then on a given Saturday, so could the statement).
The fifth and sixth examples are meaningful declarative sentences, but are not statements but rather matters of opinion or taste. Whether or not the sentence "Pegasus exists." is a statement is a subject of debate among philosophers. Bertrand Russell held that it is a (false) statement. [citation needed] Strawson held it is not a statement at all.
1.71 [logical inclusive OR]: If p and q are elementary propositions, (p ⋁ q) is an elementary proposition. Russell sums up these principles with "This completes the list of primitive propositions required for the theory of deduction as applied to elementary propositions" (PM:97).
(broadly) An example that disproves a statement or proposition, showing that it is not universally true. 2. ( to an argument form ) A counterexample to an argument form , or sequent , is an argument in the same logical form where the premises are clearly true but the conclusion is clearly false, showing that the form is invalid , since it lacks ...
In philosophy of mind and psychology, mental states are often taken to primarily consist in propositional attitudes. The propositions are usually said to be the "mental content" of the attitude. For example, if Jane has a mental state of believing that it is raining, her mental content is the proposition 'it is raining.'
In logic, the law of excluded middle or the principle of excluded middle states that for every proposition, either this proposition or its negation is true. [1] [2] It is one of the three laws of thought, along with the law of noncontradiction, and the law of identity; however, no system of logic is built on just these laws, and none of these laws provides inference rules, such as modus ponens ...