Chapter 4-4.5 Flashcards
Categorical proposition
- asserts that either all or part of the class denoted by the subject term is include or excluded from the class denoted by the predicate term
Standard form categorical proposition
1) quantifier -> all, no, some
2) subject term -> “members of the AMA” (before copula)
3) copula -> are and are not
4) predicate term -> “people holding degrees from recognized academic institutions” (after copula)
Propositions
Proposition…………….Quantity…………..Quality
1) All S are P (A) ….Universal…..Affirmative
2) No S are P (E)…..Universal….. Negative
3) Some S are P (I)…Particular .. Affirmative
4) Some S are not P (O).. Particular … Negative
Existential Fallacy
- invalid merely because the premise does not exist
- Boolean standpoint (modern square)
- only used in contrary, subcontrary and subalternation (traditional) -> when universal goes to particular
Boolean stand point
- recognizes that particular statements make a positive assertion about existence
Venn Diagrams
A) shade S side
E) shade middle
I) x in the middle
O) x in S side
Modern Square of Opposition
- Boolean standpoint
Logically undetermined-> has truth value can’t determine what it is
A———E
I———-O
Contradictory -> opposite truth values
Testing immediate inferences
- one premise and one conclusion
- plug premise into modern square of opposition
- if it works then it’s unconditionally valid regardless of existential fallacy
- illicit contrary, illicit subcontrary, illicit subalternation, illicit contraposition, illicit conversion
1) Conversion
2) illicit conversion
1) switch subject and predicate terms
2) E,I -> same truth value.
A,O -> undetermined truth value
Obversion
- change the quality
- replace predicate term with compliment (non P)
- all true
1) Contraposition
2) illicit contraposition
1) switch subject and predicate terms
- replace subject and predicate term with compliments
2) E,I -> undetermined truth value.
A,O -> determined truth value
Traditional Square of opposition
- contradictory -> opposite truth value
- contrary -> at least one is false (not both true). … If a is true e is false. But if a is false e is either false or true
- subcontrary -> at least one is true (not both false)… If I is false O is true but if I is true A could be true or false
- subalternation -> truth flows downward, falsity flows upward