# Tautology (logic)

is sometimes used to denote an arbitrary tautology, with the dual symbol (falsum) representing an arbitrary contradiction. Tautologies are a key concept in propositional logic, where a tautology is defined as a propositional formula that is true under any possible Boolean valuation of its propositional variables. In 1800, Immanuel Kant wrote in his book Logic: "The identity of concepts in analytical judgments can be either explicit (explicita) or non-explicit (implicita). Here analytic proposition refers to an analytic truth, a statement in natural language that is true solely because of the terms involved. In 1884, Gottlob Frege proposed in his Grundlagen that a truth is analytic exactly if it can be derived using logic. In 1921, in his Tractatus Logico-Philosophicus, Ludwig Wittgenstein proposed that statements that can be deduced by logical deduction are tautological (empty of meaning) as well as being analytic truths. and representing negation, the following formula can be obtained:: .

Reflective Equilibrium First published Mon Apr 28, 2003; substantive revision Wed Jan 12, 2011 Many of us, perhaps all of us, have examined our moral judgments about a particular issue by looking for their coherence with our beliefs about similar cases and our beliefs about a broader range of moral and factual issues. In this everyday practice, we have sought “reflective equilibrium” among these various beliefs as a way of clarifying for ourselves just what we ought to do. In addition, we may also have been persuading ourselves that our conclusions were justifiable and ultimately acceptable to us by seeking coherence among them. Even though it is part of our everyday practice, is this approach to deliberating about what is right and finding justification for our views defensible? Viewed most generally, a “reflective equilibrium” is the end-point of a deliberative process in which we reflect on and revise our beliefs about an area of inquiry, moral or non-moral. 1. 2. 2.1 Origins in justification of logic 3.

Vetmeduni Vienna : Press release 02-25-2014 - The importance of (experimental) design 02-25-2014 - One of the hottest debates in evolutionary biology concerns the origin of behaviour: is it genetically encoded or do animals and birds copy their parents or other individuals? A classic experiment published in 2000 seemed to provide overwhelming evidence that a particular behavioural choice (whether individuals of a species of swallow breed in a small colony or a large one) is largely genetically determined. Together with colleagues in France, Richard Wagner of the University of Veterinary Medicine, Vienna has re-examined the data and shown that the findings could be explained by random choice. The design of the original experiment – which represents a blueprint for a vast range of studies of heritability of behaviour – contains two pitfalls that combine to undermine the conclusions. There are clear advantages to living in cities: safety, ready availability of infrastructure, plenty of company etc. It's all in the genes Or is it? A question of design

Nasreddin A 17th century miniature of Nasreddin, currently in the Topkapi Palace Museum Library. Nasreddin (Turkish: Nasreddin Hoca, Ottoman Turkish: نصر الدين خواجه, Persian: خواجه نصرالدین‎, Pashto: ملا نصرالدین‎, Arabic: نصرالدین جحا‎ / ALA-LC: Naṣraddīn Juḥā, Urdu: ملا نصر الدین ‎ / ALA-LC: Mullā Naṣru l-dīn, Uzbek: Nosiriddin Xo'ja, Nasreddīn Hodja, Bosnian: Nasrudin Hodža, Albanian: Nastradin Hoxha, Nastradini) was a Seljuq satirical Sufi, believed to have lived and died during the 13th century in Akşehir, near Konya, a capital of the Seljuk Sultanate of Rum, in today's Turkey. He is considered a populist philosopher and wise man, remembered for his funny stories and anecdotes.[1] He appears in thousands of stories, sometimes witty, sometimes wise, but often, too, a fool or the butt of a joke. A Nasreddin story usually has a subtle humour and a pedagogic nature.[2] The International Nasreddin Hodja fest is celebrated between 5 and 10 July in his hometown every year.[3] According to Prof.

Systems thinking Impression of systems thinking about society[1] A system is composed of interrelated parts or components (structures) that cooperate in processes (behavior). Natural systems include biological entities, ocean currents, the climate, the solar system and ecosystems. Designed systems include airplanes, software systems, technologies and machines of all kinds, government agencies and business systems. Systems Thinking has at least some roots in the General System Theory that was advanced by Ludwig von Bertalanffy in the 1940s and furthered by Ross Ashby in the 1950s. Systems thinking has been applied to problem solving, by viewing "problems" as parts of an overall system, rather than reacting to specific parts, outcomes or events and potentially contributing to further development of unintended consequences. Systems science thinking attempts to illustrate how small catalytic events that are separated by distance and time can be the cause of significant changes in complex systems.

Jürgen Habermas Biography Habermas was born in Düsseldorf, Rhine Province, in 1929. He was born with a cleft palate and had corrective surgery twice during childhood.[4] Habermas argues that his speech disability made him think differently about the importance of communication and prefer writing over the spoken word as a medium.[5] From 1956 on, he studied philosophy and sociology under the critical theorists Max Horkheimer and Theodor Adorno at the Goethe University Frankfurt's Institute for Social Research, but because of a rift between the two over his dissertation—Horkheimer had made unacceptable demands for revision—as well as his own belief that the Frankfurt School had become paralyzed with political skepticism and disdain for modern culture[6]—he finished his habilitation in political science at the University of Marburg under the Marxist Wolfgang Abendroth. Habermas then returned to his chair at Frankfurt and the directorship of the Institute for Social Research. Teacher and mentor

List of fallacies A fallacy is incorrect argument in logic and rhetoric resulting in a lack of validity, or more generally, a lack of soundness. Fallacies are either formal fallacies or informal fallacies. Formal fallacies Main article: Formal fallacy Appeal to probability – is a statement that takes something for granted because it would probably be the case (or might be the case).[2][3]Argument from fallacy – assumes that if an argument for some conclusion is fallacious, then the conclusion is false.Base rate fallacy – making a probability judgment based on conditional probabilities, without taking into account the effect of prior probabilities.[5]Conjunction fallacy – assumption that an outcome simultaneously satisfying multiple conditions is more probable than an outcome satisfying a single one of them.[6]Masked man fallacy (illicit substitution of identicals) – the substitution of identical designators in a true statement can lead to a false one. Propositional fallacies

Zecharia Sitchin "Nibiru (hypothetical planet)" redirects here. For the "Nibiru" doomsday theory, see Nibiru cataclysm. Zecharia Sitchin (Russian: Заха́рия Си́тчин; Azerbaijani: Zaxariya Sitçin) (July 11, 1920 – October 9, 2010)[1] was an Azerbaijani-born American author of books proposing an explanation for human origins involving ancient astronauts. Sitchin's ideas have been rejected by scientists and academics, who dismiss his work as pseudoscience and pseudohistory. Early life Sitchin was born in the Azerbaijan SSR, but was raised in Mandatory Palestine. Ideas and works Sitchin posing with an enlarged, purported 6000-year-old cylinder seal impression Similar to earlier authors such as Immanuel Velikovsky and Erich von Däniken, Sitchin advocated hypotheses in which extraterrestrial events supposedly played a significant role in ancient human history. Influence Criticisms Translations and interpretations Ancient language scholar Michael S. Literalism of myth

Logical consequence Logicians make precise accounts of logical consequence regarding a given language , either by constructing a deductive system for or by formal intended semantics for language . Formal accounts The most widely prevailing view on how to best account for logical consequence is to appeal to formality. All X are Y All Y are Z Therefore, all X are Z. This is in contrast to an argument like "Fred is Mike's brother's son. A priori property of logical consequence If you know that follows logically from no information about the possible interpretations of or will affect that knowledge. is a logical consequence of cannot be influenced by empirical knowledge.[1] Deductively valid arguments can be known to be so without recourse to experience, so they must be knowable a priori.[1] However, formality alone does not guarantee that logical consequence is not influenced by empirical knowledge. Proofs and models Syntactic consequence A formula of a set of formulas if there is a formal proof in of

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