Self-contradiction or self-contradictory can refer to:
The Berry paradox is a self-referential paradox arising from an expression like "The smallest positive integer not definable in under sixty letters".
In logic, the law of non-contradiction (LNC) states that contradictory propositions cannot both be true in the same sense at the same time, e. g. the two propositions "p is the case" and "p is not the case" are mutually exclusive. Formally this is expressed as the tautology ¬(p ∧ ¬p). The law is not to be confused with the law of excluded middle which states that at least one, "p is the case" or "p is not the case" holds.
An oxymoron is a figure of speech that juxtaposes concepts with opposing meanings within a word or phrase that creates an ostensible self-contradiction. An oxymoron can be used as a rhetorical device to illustrate a rhetorical point or to reveal a paradox. A more general meaning of "contradiction in terms" is recorded by the OED for 1902.
Omnipotence is the quality of having unlimited power. Monotheistic religions generally attribute omnipotence only to the deity of their faith. In the monotheistic religious philosophy of Abrahamic religions, omnipotence is often listed as one of a deity's characteristics, along with omniscience, omnipresence, and omnibenevolence. The presence of all these properties in a single entity has given rise to considerable theological debate, prominently including the problem of evil, the question of why such a deity would permit the existence of evil. It is accepted in philosophy and science that omnipotence can never be effectively understood.
A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. It is a statement that, despite apparently valid reasoning from true premises, leads to a seemingly self-contradictory or a logically unacceptable conclusion. A paradox usually involves contradictory-yet-interrelated elements that exist simultaneously and persist over time.
In logic and mathematics, proof by contradiction is a form of proof that establishes the truth or the validity of a proposition, by showing that assuming the proposition to be false leads to a contradiction. Proof by contradiction is also known as indirect proof, proof by assuming the opposite, and reductio ad impossibile.
Truth is the property of being in accord with fact or reality. In everyday language, truth is typically ascribed to things that aim to represent reality or otherwise correspond to it, such as beliefs, propositions, and declarative sentences.
In traditional logic, a contradiction occurs when a proposition conflicts either with itself or established fact. It is often used as a tool to detect disingenuous beliefs and bias. Illustrating a general tendency in applied logic, Aristotle's law of noncontradiction states that "It is impossible that the same thing can at the same time both belong and not belong to the same object and in the same respect."
In epistemology, a self-evident proposition is a proposition that is known to be true by understanding its meaning without proof, and/or by ordinary human reason.
Dialetheism is the view that there are statements which are both true and false. More precisely, it is the belief that there can be a true statement whose negation is also true. Such statements are called "true contradictions", dialetheia, or nondualisms.
In classical logic, intuitionistic logic and similar logical systems, the principle of explosion, or the principle of Pseudo-Scotus, is the law according to which any statement can be proven from a contradiction. That is, once a contradiction has been asserted, any proposition can be inferred from it; this is known as deductive explosion.
Meta is a prefix meaning "more comprehensive" or "transcending."
The laws of thought are fundamental axiomatic rules upon which rational discourse itself is often considered to be based. The formulation and clarification of such rules have a long tradition in the history of philosophy and logic. Generally they are taken as laws that guide and underlie everyone's thinking, thoughts, expressions, discussions, etc. However, such classical ideas are often questioned or rejected in more recent developments, such as intuitionistic logic, dialetheism and fuzzy logic.
Subjunctive possibility is a form of modality studied in modal logic. Subjunctive possibilities are the sorts of possibilities considered when conceiving counterfactual situations; subjunctive modalities are modalities that bear on whether a statement might have been or could be true—such as might, could, must, possibly, necessarily, contingently, essentially, accidentally, and so on. Subjunctive possibilities include logical possibility, metaphysical possibility, nomological possibility, and temporal possibility.
In philosophy and rhetoric, the principle of charity or charitable interpretation requires interpreting a speaker's statements in the most rational way possible and, in the case of any argument, considering its best, strongest possible interpretation. In its narrowest sense, the goal of this methodological principle is to avoid attributing irrationality, logical fallacies, or falsehoods to the others' statements, when a coherent, rational interpretation of the statements is available. According to Simon Blackburn, "it constrains the interpreter to maximize the truth or rationality in the subject's sayings."
The barbershop paradox was proposed by Lewis Carroll in a three-page essay titled "A Logical Paradox", which appeared in the July 1894 issue of Mind. The name comes from the "ornamental" short story that Carroll uses in the article to illustrate the paradox. It was in existence previously in several alternative forms in his writing and correspondence, not always involving a barbershop. Carroll described it as illustrating "a very real difficulty in the Theory of Hypotheticals". From the viewpoint of modern logic it is seen not so much as a paradox than as a simple logical error. It is of interest now mainly as an episode in the development of algebraic logical methods when these were not so widely understood, although the problem continues to be discussed in relation to theories of implication and modal logic.
Owing to its origin in ancient Greece and Rome, English rhetorical theory frequently employs Greek and Latin words as terms of art. This page explains commonly used rhetorical terms in alphabetical order. The brief definitions here are intended to serve as a quick reference rather than an in-depth discussion. For more information, click the terms.
In semantics, philosophy of language, metaphysics, and metasemantics, meaning "is a relationship between two sorts of things: signs and the kinds of things they intend, express, or signify".
A self-refuting idea or self-defeating idea is an idea or statement whose falsehood is a logical consequence of the act or situation of holding them to be true. Many ideas are called self-refuting by their detractors, and such accusations are therefore almost always controversial, with defenders stating that the idea is being misunderstood or that the argument is invalid. For these reasons, none of the ideas below are unambiguously or incontrovertibly self-refuting. These ideas are often used as axioms, which are definitions taken to be true, and cannot be used to test themselves, for doing so would lead to only two consequences: consistency or exception (self-contradiction). It is important to know that the conclusion of an argument that is self-refuting is not necessarily false, since it could be supported by another, more valid, argument.
In logic, specifically in deductive reasoning, an argument is valid if and only if it takes a form that makes it impossible for the premises to be true and the conclusion nevertheless to be false. It is not required for a valid argument to have premises that are actually true, but to have premises that, if they were true, would guarantee the truth of the argument's conclusion. Valid arguments must be clearly expressed by means of sentences called well-formed formulas.