Chapter 6 Flashcards
Syllogism:
A deductive argument that has exactly two premises and a conclusion.
Categorical syllogism:
A syllogism constructed entirely of categorical propositions. It contains three different terms, each of which is used two times.
Minor term:
The subject of the conclusion of a categorical syllogism.
Major term:
The predicate of the conclusion of a categorical syllogism.
Middle term:
The term that occurs only in the premises of a categorical syllogism.
Major premise:
The first premise of a categorical syllogism contains the major term.
Minor premise:
The second premise of a categorical syllogism contains the minor term.
Standard-form Categorical Syllogism:
In order to be a standard-form categorical syllogism, three requirements must be met: (1) All three statements must be standard-form categorical propositions. (2) The two occurrences of each term must be identical and have the same sense. (3) The major premise must occur first, the minor premise second, and the conclusion last.
Categorical Syllogisms
A deductive argument constructed entirely of categorical propositions with exactly two premises and a conclusion.
Mood:
The mood of a categorical syllogism consists of the type of categorical propositions involved (A, E, I, or O) and the order in which they occur.
Figure:
The middle term can be arranged in the two premises in four different ways. These placements determine the figure of the categorical syllogism.
Undistributed middle:
A formal fallacy that occurs when the middle term in a categorical syllogism is undistributed in both premises of a categorical syllogism.
Illicit major:
A formal fallacy that occurs when the major term in a categorical syllogism is distributed in the conclusion but not in the major premise.
Illicit minor:
A formal fallacy that occurs when the minor term in a categorical syllogism is distributed in the conclusion but not in the minor premise.
Exclusive premises:
A formal fallacy that occurs when both premises in a categorical syllogism are negative.
Affirmative conclusion/negative premise:
A formal fallacy that occurs when a categorical syllogism has a negative premise and an affirmative conclusion.
Negative conclusion/affirmative premises:
A formal fallacy that occurs when a categorical syllogism has a negative conclusion and two affirmative premises.
Existential fallacy:
A formal fallacy that occurs when a categorical syllogism has a particular conclusion and two universal premises.
Rules for distribution
Rule 1: The middle term must be distributed in at least one premise.
Rule 2: If a term is distributed in the conclusion, then it must be distributed in a premise.
Rule 3: A categorical syllogism cannot have two negative premises.
Rule 4: A negative premise must have a negative conclusion.
Rule 5: A negative conclusion must have a negative premise.
Rule 6: Two universal premises cannot have a particular conclusion.
How to reduce the number of terms in an argument
Eliminate needless words
Substitute words that are synonyms
Substitute complements for terms
Use conversion, obversion, contraposition to simplify propositions
Change order of premises to put syllogism in standard form
Substitute class terms and copula
Enthymemes:
Arguments with missing premises, missing conclusions, or both.
