Syllogistic fallacy
Encyclopedia
Syllogistic fallacies are logical fallacies that occur in syllogism
s. They include:
Any syllogism type (other than polysyllogism
and disjunctive):
Occurring in categorical syllogisms:
Occurring in disjunctive syllogism
s:
Occurring in statistical syllogism
s (dicto simpliciter
fallacies):
Syllogism
A syllogism is a kind of logical argument in which one proposition is inferred from two or more others of a certain form...
s. They include:
Any syllogism type (other than polysyllogism
Polysyllogism
A polysyllogism is a string of any number of propositions forming together a sequence of syllogisms such that the conclusion of each syllogism, together with the next proposition, is a premise for the next, and so on...
and disjunctive):
- fallacy of four termsFallacy of four termsThe fallacy of four terms is the logical fallacy that occurs when a syllogism has four terms rather than the requisite three. This form of argument is thus invalid.- Explanation :Categorical syllogisms always have three terms:...
Occurring in categorical syllogisms:
- related to affirmative or negative premises:
- affirmative conclusion from a negative premiseAffirmative conclusion from a negative premiseAffirmative conclusion from a negative premise is a logical fallacy that is committed when a categorical syllogism has a positive conclusion, but one or two negative premises.For example:...
- fallacy of exclusive premisesFallacy of exclusive premisesThe fallacy of exclusive premises is a syllogistic fallacy committed in a categorical syllogism that is invalid because both of its premises are negative.Example of an EOO-4 invalid proposition:...
- negative conclusion from affirmative premisesNegative conclusion from affirmative premisesNegative conclusion from affirmative premises is a syllogistic fallacy committed when a categorical syllogism has a negative conclusion yet both premises are affirmative...
- affirmative conclusion from a negative premise
- existential fallacyExistential fallacyThe existential fallacy, or existential instantiation, is a logical fallacy in Boolean logic while it is not in Aristotelian logic. In an existential fallacy, we presuppose that a class has members even when we are not explicitly told so; that is, we assume that the class has existential import.An...
- fallacy of the undistributed middleFallacy of the undistributed middleThe fallacy of the undistributed middle is a logical fallacy, and more specifically a formal fallacy, that is committed when the middle term in a categorical syllogism is not distributed in the major premise...
- illicit majorIllicit majorIllicit major is a logical 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...
- illicit minorIllicit minorIllicit minor is a logical fallacy committed in a categorical syllogism that is invalid because its minor term is undistributed in the minor premise but distributed in the conclusion....
- fallacy of necessityFallacy of necessityA fallacy of necessity is a fallacy in the logic of a syllogism whereby a degree of unwarranted necessity is placed in the conclusion.Example:Because c) presumes b) will always be the case, it is a fallacy of necessity...
Occurring in disjunctive syllogism
Disjunctive syllogism
A disjunctive syllogism, also known as disjunction-elimination and or-elimination , and historically known as modus tollendo ponens,, is a classically valid, simple argument form:where \vdash represents the logical assertion....
s:
Occurring in statistical syllogism
Statistical syllogism
A statistical syllogism is a non-deductive syllogism. It argues from a generalization true for the most part to a particular case .-Introduction:Statistical syllogisms may use qualifying words like "most", "frequently", "almost never", "rarely",...
s (dicto simpliciter
Dicto simpliciter
A dicto simpliciter or ad dictum simpliciter are Latin phrases for a type of logical fallacy.A dicto simpliciter fallacies are deductive fallacies that occur in statistical syllogisms...
fallacies):
- accidentAccident (fallacy)The logical fallacy of accident is a deductive fallacy occurring in statistical syllogisms when an exception to a rule of thumb is ignored. It is one of the thirteen fallacies originally identified by Aristotle...
- converse accidentConverse accidentThe logical fallacy of converse accident is a deductive fallacy that can occur in a statistical syllogism when an exception to a generalization is wrongly called for.For example:The inductive version of this fallacy is called hasty generalization...