Ambitious
Having two or more meanings
Affirmative sentence
A sentence that affirms class membership.
Categorical argument
An argument composed of categorical sentences
Categorical logic
The study of arguments that are composed of categorical sentences
Categorical sentence
A sentence asserting at all, or some, of one category of things belong or do not belong to another category of things
Class
A collection objects having a specified characteristic in common
Complement of a class
The class consisting of all those things outside the class
Contradictories
Two statements are contradictories and only if they cannot be true and they cannot both be false. In all possible situations, if one is true, the other is false.
Contrapositive
The sentence that results if you perform the following two operations on the categorical sentence: switch the subject and predicate. Replace each term with its term complement.
Contraries
Two statements or contraries they cannot both be true, but might both be false. If two statements are contraries, at least one is false.
Converse of a sentence
The sentence that results if we switch the subject and predicate terms in a categorical sentence.
Copula
A word that links the subject term with the predicate term.
Immediate inference
An argument composed of exactly one premise and one conclusion immediately drawn from it.
Logical equivalence
Two statements are logically equivalent if they imply each other, which is to say that in all situations the have matching truth-values.
Logical form of an argument
An abstract logical structure that many arguments about many subjects have in common
Logical form of a sentence
An abstract logical structure that many sentences may have in common
Mediate inference
In the argument composed of two categorical premises and one conclusion, in which the reasoning from the first premise to the conclusion is mediated by passing through a second premise.
Negative sentence
A sentence in which a class membership is denied.
Obverse of a sentence
The sentence that results if you perform the following two operations on categorical sentence: change the quality without changing the quantity from affirmative to negative or negative to affirmative. Replace the predicate term with its term complement.
Particular
Pertaining to one or more members of a category
Particular affirmative sentence
Categorical sentence asserting that some of the members of one category things belong to a second category of things
Particular negative sentence
Categorical sentence asserting that some of the members of one category of things does not belong to the second category of things.
Particular sentence
A categorical sentence that makes a claim about some of the class denoted by the subject term.
Quantifier
A word such as all or some that specifies a quantity for the subject term of the sentence.
Singular statement
A sentence that makes a assertion about a specifically identified entity or thing.
Some
One or more, at least one. Possibly all.
Sorites
A series of four or more categorical statements with one of the statements designated as the conclusion and the rest as premises.
Square of opposition
A table representing end logical relations between corresponding categorical sentences.
Subcontraries
Two statements that cannot both be false, but that might be true. If two statements are subcontraries, at least one is true.
Term complement
The term denoting the class complement
Truth-value
The value a sentence has when it is true or false. When a sentence is true, it has the truth-value of true and when a sentence is false, false
Universal
Pertaining to all the members of a category
Universal affirmative sentence
A categorical sentence asserting that all the members of one category belong to a second category of things.
Universal negative sentence
A categorical sentence asserting that none of the member of one category of things belongs to a second category of things.
Universal sentence
A categorical sentence that makes a claim about every member of the class denoted by subject term.
Vague
Having fuzzy boundaries of application
Type A
Universal affirmative
All S are P
Type E
Universal negative
No S are P
Type I
Particular affirmative
Some S are P
Type O
Particular Negative
Some S are not P
Square of opposition graph
A (all s are p) E (no s are p)
^ ^
\ /
\ /
\ /
\ Contradictions /
/ \ / \ / \ / \ v v I (some s are p) O (some s are not p)