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A false premise is an incorrect proposition that forms the basis of an argument or syllogism. ... For example, consider this syllogism, which involves a false premise:
An example of a syllogism of the third figure is: All mammals are air-breathers, All mammals are animals, Therefore, some animals are air-breathers. This validly follows only if an immediate inference is silently interpolated. The added inference is a conversion that uses the word "some" instead of "all." All mammals are air-breathers,
Each premise and the conclusion can be of type A, E, I or O, and the syllogism can be any of the four figures. A syllogism can be described briefly by giving the letters for the premises and conclusion followed by the number for the figure. For example, the syllogism BARBARA below is AAA-1, or "A-A-A in the first figure".
Syllogistic fallacies – logical fallacies that occur in syllogisms. Affirmative conclusion from a negative premise (illicit negative) – a categorical syllogism has a positive conclusion, but at least one negative premise. [11] Fallacy of exclusive premises – a categorical syllogism that is invalid because both of its premises are negative ...
In this example, distribution is marked in boldface: All Z is B; All Y is B; Therefore, all Y is Z; B is the common term between the two premises (the middle term) but is never distributed, so this syllogism is invalid. B would be distributed by introducing a premise which states either All B is Z, or No B is Z.
Sometimes a syllogism that is apparently fallacious because it is stated with more than three terms can be translated into an equivalent, valid three term syllogism. [2] For example: Major premise: No humans are immortal. Minor premise: All Greeks are people. Conclusion: All Greeks are mortal.
Equivalently, if P is true or Q is true and P is false, then Q is true. The name "disjunctive syllogism" derives from its being a syllogism, a three-step argument, and the use of a logical disjunction (any "or" statement.) For example, "P or Q" is a disjunction, where P and Q are called the statement's disjuncts.
Arguments which violate the rules of syllogisms. Pages in category "Syllogistic fallacies" ... False premise; Fallacy of four terms; I. Illicit contrary; Illicit major;