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List Of Logical Fallacies
A fallacy is reasoning that is logically invalid, or that undermines the logical validity of an argument. All forms of human communication can contain fallacies. Because of their variety, fallacies are challenging to classify. They can be classified by their structure (formal fallacies) or content (informal fallacies). Informal fallacies, the larger group, may then be subdivided into categories such as improper presumption, faulty generalization, and error in assigning causation and relevance, among others. The use of fallacies is common when the speaker's goal of achieving common agreement is more important to them than utilizing sound reasoning. When fallacies are used, the premise should be recognized as not well-grounded, the conclusion as unproven (but not necessarily false), and the argument as unsound. Formal fallacies A formal fallacy is an error in the argument's form. All formal fallacies are types of . * Appeal to probability – a statement that takes something f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fallacy
A fallacy is the use of invalid or otherwise faulty reasoning, or "wrong moves," in the construction of an argument which may appear stronger than it really is if the fallacy is not spotted. The term in the Western intellectual tradition was introduced in the Aristotelian '' De Sophisticis Elenchis''. Some fallacies may be committed intentionally to manipulate or persuade by deception. Others may be committed unintentionally because of human limitations such as carelessness, cognitive or social biases and ignorance, or, potentially, as the inevitable consequence of the limitations of language and understanding of language. This includes ignorance of the right reasoning standard, but also ignorance of relevant properties of the context. For instance, the soundness of legal arguments depends on the context in which the arguments are made. Fallacies are commonly divided into "formal" and "informal." A formal fallacy is a flaw in the structure of a deductive argument which ren ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Affirming The Consequent
Affirming the consequent, sometimes called converse error, fallacy of the converse, or confusion of necessity and sufficiency, is a formal fallacy of taking a true conditional statement (e.g., "If the lamp were broken, then the room would be dark"), and invalidly inferring its converse ("The room is dark, so the lamp is broken"), even though that statement may not be true. This arises when a consequent ("the room would be dark") has other possible antecedents (for example, "the lamp is in working order, but is switched off" or "there is no lamp in the room"). Converse errors are common in everyday thinking and communication and can result from, among other causes, communication issues, misconceptions about logic, and failure to consider other causes. The opposite statement, denying the consequent, ''is'' a valid form of argument (modus tollens). Formal description Affirming the consequent is the action of taking a true statement P \to Q and invalidly concluding its converse Q \ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illicit Major
Illicit major is a formal fallacy committed in a categorical syllogism that is invalid because its major term is undistributed in the major premise but distributed in the conclusion. This fallacy has the following argument form: #''All A are B'' #''No C are A'' #''Therefore, no C are B'' Example: #''All dogs are mammals'' #''No cats are dogs'' #''Therefore, no cats are mammals'' In this argument, the major term is "mammals". This is distributed in the conclusion (the last statement) because we are making a claim about a property of ''all'' mammals: that they are not cats. However, it is not distributed in the major premise (the first statement) where we are only talking about a property of ''some'' mammals: Only some mammals are dogs. The error is in assuming that the converse of the first statement (that all mammals are dogs) is also true. However, an argument in the following form differs from the above, and is valid (Camestres): #''All A are B'' #''No B are C'' #''Therefore, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fallacy Of Four Terms
The fallacy of four terms ( la, quaternio terminorum) is the formal fallacy that occurs when a syllogism has four (or more) terms rather than the requisite three, rendering it invalid. Definition Categorical syllogisms always have three terms: :Major premise: All fish have fins. :Minor premise: All goldfish are fish. :Conclusion: All goldfish have fins. Here, the three terms are: "goldfish", "fish", and "fins". Using four terms invalidates the syllogism: :Major premise: All fish have fins. :Minor premise: All goldfish are fish. :Conclusion: All humans have fins. The premises do not connect "humans" with "fins", so the reasoning is invalid. Notice that there are four terms: "fish", "fins", "goldfish" and "humans". Two premises are not enough to connect four different terms, since in order to establish connection, there must be one term common to both premises. In everyday reasoning, the fallacy of four terms occurs most frequently by equivocation: using the same word or phra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fallacy Of Exclusive Premises
A fallacy is the use of invalid or otherwise faulty reasoning, or "wrong moves," in the construction of an argument which may appear stronger than it really is if the fallacy is not spotted. The term in the Western intellectual tradition was introduced in the Aristotelian '' De Sophisticis Elenchis''. Some fallacies may be committed intentionally to manipulate or persuade by deception. Others may be committed unintentionally because of human limitations such as carelessness, cognitive or social biases and ignorance, or, potentially, as the inevitable consequence of the limitations of language and understanding of language. This includes ignorance of the right reasoning standard, but also ignorance of relevant properties of the context. For instance, the soundness of legal arguments depends on the context in which the arguments are made. Fallacies are commonly divided into "formal" and "informal." A formal fallacy is a flaw in the structure of a deductive argument which r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syllogism
A syllogism ( grc-gre, συλλογισμός, ''syllogismos'', 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true. In its earliest form (defined by Aristotle in his 350 BCE book '' Prior Analytics''), a syllogism arises when two true premises (propositions or statements) validly imply a conclusion, or the main point that the argument aims to get across. For example, knowing that all men are mortal (major premise) and that Socrates is a man (minor premise), we may validly conclude that Socrates is mortal. Syllogistic arguments are usually represented in a three-line form: All men are mortal. Socrates is a man. Therefore, Socrates is mortal.In antiquity, two rival syllogistic theories existed: Aristotelian syllogism and Stoic syllogism. From the Middle Ages onwards, ''categorical syllogism'' and ''syllogism'' were usually used interchangeably. This a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Affirmative Conclusion From A Negative Premise
Affirmative conclusion from a negative premise (illicit negative) is a formal fallacy that is committed when a categorical syllogism has a positive conclusion and one or two negative premises. For example: :''No fish are dogs, and no dogs can fly, therefore all fish can fly.'' The only thing that can be properly inferred from these premises is that some things that are not fish cannot fly, provided that dogs exist. Or: :''We don't read that trash. People who read that trash don't appreciate real literature. Therefore, we appreciate real literature.'' This could be illustrated mathematically as :If A \cap B = \emptyset and B \cap C = \emptyset then A\subset C. It is a fallacy because any valid forms of categorical syllogism that assert a negative premise must have a negative conclusion. See also * Negative conclusion from affirmative premises, in which a syllogism is invalid because the conclusion is negative yet the premises are affirmative * Fallacy of exclusive premises A ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syllogisms
A syllogism ( grc-gre, συλλογισμός, ''syllogismos'', 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true. In its earliest form (defined by Aristotle in his 350 BCE book '' Prior Analytics''), a syllogism arises when two true premises (propositions or statements) validly imply a conclusion, or the main point that the argument aims to get across. For example, knowing that all men are mortal (major premise) and that Socrates is a man (minor premise), we may validly conclude that Socrates is mortal. Syllogistic arguments are usually represented in a three-line form: All men are mortal. Socrates is a man. Therefore, Socrates is mortal.In antiquity, two rival syllogistic theories existed: Aristotelian syllogism and Stoic syllogism. From the Middle Ages onwards, ''categorical syllogism'' and ''syllogism'' were usually used interchangeably. This a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Syllogistic Fallacy
A syllogism ( grc-gre, συλλογισμός, ''syllogismos'', 'conclusion, inference') is a kind of logical argument that applies deductive reasoning to arrive at a conclusion based on two propositions that are asserted or assumed to be true. In its earliest form (defined by Aristotle in his 350 BCE book ''Prior Analytics''), a syllogism arises when two true premises (propositions or statements) validly imply a conclusion, or the main point that the argument aims to get across. For example, knowing that all men are mortal (major premise) and that Socrates is a man (minor premise), we may validly conclude that Socrates is mortal. Syllogistic arguments are usually represented in a three-line form: All men are mortal. Socrates is a man. Therefore, Socrates is mortal.In antiquity, two rival syllogistic theories existed: Aristotelian syllogism and Stoic syllogism. From the Middle Ages onwards, ''categorical syllogism'' and ''syllogism'' were usually used interchangeably. This ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Existential Fallacy
The existential fallacy, or existential instantiation, is a formal fallacy. In the existential fallacy, one presupposes that a class has members when one is not supposed to do so; i.e., when one should not assume existential import. Not to be confused with the 'Affirming the consequent', which states "A causes B; B, therefore A". One example would be: "''Every unicorn has a horn on its forehead''". It does not imply that there are any unicorns at all in the world, and thus it cannot be assumed that, if the statement were true, somewhere there is a unicorn in the world (with a horn on its forehead). The statement, if assumed true, implies only that if there were any unicorns, each would definitely have a horn on its forehead. Overview An existential fallacy is committed in a medieval categorical syllogism because it has two universal premises and a particular conclusion with no assumption that at least one member of the class exists, an assumption which is not established by the p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantification (logic)
In logic, a quantifier is an operator that specifies how many individuals in the domain of discourse satisfy an open formula. For instance, the universal quantifier \forall in the first order logic, first order formula \forall x P(x) expresses that everything in the domain satisfies the property denoted by P. On the other hand, the existential quantifier \exists in the formula \exists x P(x) expresses that there exists something in the domain which satisfies that property. A formula where a quantifier takes widest scope (logic), scope is called a quantified formula. A quantified formula must contain a Free variables and bound variables, bound variable and a subformula specifying a property of the referent of that variable. The mostly commonly used quantifiers are \forall and \exists. These quantifiers are standardly defined as Dual (mathematics), duals; in classical logic, they are interdefinable using negation. They can also be used to define more complex quantifiers, as i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Denying The Antecedent
Denying the antecedent, sometimes also called inverse error or fallacy of the inverse, is a formal fallacy of inferring the inverse from the original statement. It is committed by reasoning in the form: :If ''P'', then ''Q''. :Therefore, if not ''P'', then not ''Q''. which may also be phrased as :P \rightarrow Q (P implies Q) :\therefore \neg P \rightarrow \neg Q (therefore, not-P implies not-Q) Arguments of this form are invalid. Informally, this means that arguments of this form do not give good reason to establish their conclusions, even if their premises are true. In this example, a valid conclusion would be: ~P or Q. The name ''denying the antecedent'' derives from the premise "not ''P''", which denies the "if" clause of the conditional premise. One way to demonstrate the invalidity of this argument form is with an example that has true premises but an obviously false conclusion. For example: :If you are a ski instructor, then you have a job. :You are not a ski ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
