logical Opposition Flashcards
The relationship between two propositions that have the same subject and predicate but have different quantity or quality.
The process of inferring or deriving from the known proposition (a proposition that is already assumed to be true or false) an opposite proposition.
Logical opposition
Aka logical opposition
Oppositional inference
the upgrading or adjustment of belief in the light of the play of new information upon current beliefs.
It is a process by which one proposition is arrived at and affirmed on the basis of some other proposition or propositions.
Inference
kinds of inference
Immediate inference
mediate inference
Kind of inference
this is a process of drawing a conclusion from only one given proposition.
example:
No man is an ape,
therefore, no ape is a man.
immediate inference
Kind of Inference
this is a process of drawing a conclusion from two given propositions through the mediation of a third concept common to both propositions. It is in this kind of reasoning that there can be a real progress in human knowledge. This is considered, therefore, as the reasoning proper.
example:
All Filipinos are lovers of truth.
But Apolinario Mabini is a Filipino.
Therefore, Apolinario Mabini is a lover of truth.
Mediate inference
4 Kinds of logical oppositions and their truth value
Contradictory opposition (CD)
Contrary opposition (CT)
Sub Contrary opposition (SC)
Sub Altern opposition (SA)
Kind of logical opposition
all S are P (A-prop) ➡️ not all S are P (O-prop)
Contradictory opposition (CD)
Kind of logical oppositions
no S are P (E-prop) ➡️ some S are P (I-prop)
Contradictory opposition (CD)
Kind of logical opposition
If all Filipinos are patriotic is TRUE,
then not all Filipinos are patriotic will be FALSE.
Contradictory opposition (CD)
Kind of logical opposition
If some students are studious is FALSE,
then no students are studious is TRUE.
Contradictory opposition (CD)
Kind of logical opposition
All S are P (A-prop) ➡️ no S are P (E-prop)
Contrary opposition (CT)
Kind of logical opposition
If all bananas are fruits is TRUE,
then No bananas are fruits will be FALSE.
Contrary opposition (CT)
Kind of logical opposition
If all Filipinos are artists is FALSE,
then no Filipinos are artists is DOUBTFUL.
Contrary opposition (CT)
Kind of logical opposition
Some S are P (I-prop) ➡️ Not all S are P (O-prop)
Sub Contrary opposition (SC)
Kind of logical opposition
Some students are lovers of Logic is TRUE; hence, not all students lovers of Logic is DOUBTFUL.
Sub Contrary opposition (SC)
Kind of logical opposition
if not all saints are martyrs is FALSE; then, some saints are Martyrs is TRUE.
Sub Contrary opposition (SC)
Kind of logical opposition
All S are P. (A-prop) ➡️ some S are P (I-prop)
Sub Altern opposition (SA)
Kind of logical opposition
No S are P. (E-prop) ➡️ not all S are P (O-prop)
Sub Altern opposition (SA)
Kind of Logical Opposition
If all Logic students are studious is TRUE.
It follows that some Logic students are studious is also TRUE.
Sub Altern opposition (SA)
Kind of Logical Opposition
If no congressman are corrupt officials is FALSE, then not all congressmen are corrupt officials is DOUBTFUL.
Sub Altern opposition (SA)
Kind of Logical Opposition
If some teachers are loving persons is TRUE, then all teachers are loving persons will be DOUBTFUL.
Sub Altern opposition (SA)
Kind of Logical Opposition
If some NPA rebels are criminals is FALSE, then all NPA rebels are criminals will also be FALSE.
Sub Altern opposition (SA)
T ➡️ F
F ➡️ T
Contradictory opposition
T ➡️ F
F ➡️ D
Contrary opposition
T ➡️ D
F ➡️ T
Sub Contrary opposition
T ➡️ T
F ➡️ D
T ➡️ D
F ➡️ F
Sub Altern opposition
