- quantifier shift fallacy
- A fallacy of reversing the order of two quantifiers . The common form is that of moving from a statement of the form ‘every x has a related y ’ to one of the form ‘there is some y related to every x ’. An easily detected instance would be inferring from ‘everyone has a mother’ to ‘there is someone who is everyone's mother’. More subtle instances would be trading on the two different meanings that can be given to statements like ‘there is some proposition presupposed in every investigation’. Does this mean that for all investigations there is some possibly different presupposition, or that there is some unique common presupposition? Similarly ‘there is something that is the meaning of all our activities’, which smooths the fallacious transition from ‘each activity has a meaning’ which is probably true to ‘there is a Purpose common to all of them’ which is probably false. The fallacy is obvious in quantification theory, where it is represented as moving from (∀x )(∃y )(Rxy ) to (∃y )(∀x )(Rxy ).
Philosophy dictionary. Academic. 2011.
Look at other dictionaries:
Quantifier shift — A logical fallacy in which the quantifiers of a statement are erroneously transposed. The change in the logical nature of the statement may not be obvious when it is stated in a natural language like English. Definition The fallacious deduction… … Wikipedia
Fallacy — In logic and rhetoric, a fallacy is usually incorrect argumentation in reasoning resulting in a misconception or presumption. By accident or design, fallacies may exploit emotional triggers in the listener or interlocutor (appeal to emotion), or… … Wikipedia
Naturalistic fallacy — The naturalistic fallacy is often claimed to be a formal fallacy. It was described and named by British philosopher G. E. Moore in his 1903 book Principia Ethica. Moore stated that a naturalistic fallacy is committed whenever a philosopher… … Wikipedia
Deductive fallacy — A deductive fallacy is defined as a deductive argument that is invalid. The argument itself could have true premises, but still have a false conclusion. Thus, a deductive fallacy is a fallacy where deduction goes wrong, and is no longer a… … Wikipedia
Masked man fallacy — The masked man fallacy is a fallacy of formal logic in which substitution of identical designators[clarification needed] in a true statement can lead to a false one. One form of the fallacy may be summarized as follows: Premise 1: I know who X is … Wikipedia
List of philosophy topics (I-Q) — II and thou I Ching I Ching I proposition I Thou I Thou relationshipIaIamblichus (philosopher)IbYahya Ibn Adi Yahya Ibn Adi Ibn al Arabi Muhyi al Din Ibn al Arabi Abu Bakr Ibn Bajja Abu Bakr Ibn Bājja Abu Bakr Muhammad Ibn Yahya Ibn as Say igh… … Wikipedia
life, meaning of — For nearly everyone it is important to think that his or her life has a purpose. But these purposes may be various: the purpose of one person s life may be to achieve one kind of goal, that of another person may be to achieve a very different… … Philosophy dictionary
Outline of logic — The following outline is provided as an overview of and topical guide to logic: Logic – formal science of using reason, considered a branch of both philosophy and mathematics. Logic investigates and classifies the structure of statements and… … Wikipedia
List of fallacies — For specific popular misconceptions, see List of common misconceptions. A fallacy is incorrect argumentation in logic and rhetoric resulting in a lack of validity, or more generally, a lack of soundness. Contents 1 Formal fallacies 1.1… … Wikipedia
False dilemma — A false dilemma (also called false dichotomy, the either or fallacy, fallacy of false choice, black and white thinking, or the fallacy of exhaustive hypotheses) is a type of logical fallacy that involves a situation in which only two alternatives … Wikipedia