Aspects of this topic are discussed in the following places at Britannica.
...as their values.) Hence they are often called propositional variables. It is assumed that every proposition is either true or false and that no proposition is both true and false. Truth and falsity are said to be the truth values of propositions. The function of an operator is to form a new proposition from one or more given propositions, called the arguments of the operator. The...
in formal logic: Nonstandard versions of PC )Underlying ordinary PC is the intuitive idea that every proposition is either true or false, an idea that finds its formal expression in the stipulation that variables shall have two possible values only—namely, 1 and 0. (For this reason the system is often called the two-valued propositional calculus.) This idea has been challenged on various grounds. Following a suggestion made by...
...to mean “there exists . . . ”) can be read “There exists a proposition p such that p is true and p is among the answers of Q.” Otherwise it is false—i.e., all its answers are false. If he never came at all, the question “On what day of the week did he come?” is a false question in the sense that it lacks any true...
There can be false knowledge only in the sense that “he thought he knew that p, but he was mistaken.” When the falsity of purported knowledge becomes manifest, the claim to knowledge must be withdrawn. “I know that p, but it may be false that p” is a contradiction in terms. When something is asserted or admitted as known, it follows that this must be...
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