Logic

2. 1. CONVERSION
SIMPLE CONVERSION
1. Transpose the subject and predicate
2. Retain quality
Applicable to I and E
I to I
Many treasure hunters are successful businessman
Many successful businessman are treasure hunters.
E to E
No Protestants are Catholics.
No Catholics are Protestants.

3. 1. CONVERSION
PARTIAL CONVERSION
1. Change from Universal to Particular
2. Retain quality
A to I and E to O
A to I
Every Filipino is an Asian. All singers are entertainers.
Some Asians are Filipinos. Some entertainers are singers
E to O
No stars are galaxies. No mountains are hills.
Some galaxies are not stars. Some hills are not mountains.

4. 2. OBVERSION
1. Retain subject and quantity.
2. Transpose quality.
3. Change the original predicate to a contradictory term.
A to E, E to A and I to O, O to I
A toE E to A
All Dolphins are sea creatures. No flowers are roots.
All dolphins are not non-sea creatures. All roots are non-flowers.
I to O
Some students are not studious.
Some students are not non-studious.
O to I
Several accounting graduates are not CPAs.
Several accounting graduates are non-CPAs.

5. 3. CONTRAPOSITION
SIMPLE CONTRAPOSITION
1. Obvert
2. Convert
Applicable to A to E, E to I and O to I.
Example: A to E
All Inventors are scientists.
Obvert: No inventors are non-scientists.
Convert: No non-scientists are inventors.
Hence: NO NON-SCIENTISTS ARE INVENTORS.

6. 3. CONTRAPOSITION
COMPLETE CONTRAPOSITION
1. Obvert
2. Convert
3. Obvert again.
Applicable to A to A, E to O and O to O.
Example: A to A
All princes are of noble origin
Obvert: No princes are of non-noble origin.
Convert: No non-noble origin are princes.
Obvert again: All non-noble origin are non-princes.
Hence: ALL NON-NOBLE ORIGIN ARE NON-PRINCES.

7. 4. INVERSION
SIMPLE INVERSION
1. Present contradictory and original subject.
2. Change quality.
3. Retain the predicate.
Applicable to A to O and E to I.
Example: A to O
Every creature is an organism.
Some non-creature is not an organism.
E to I
No man is winged.
Some non-man is winged.

8. 4. INVERSION
COMPLETE INVERSION
1. Retain subject and predicate.
2. Present contradictory both subject and predicate.
3. Never change the quality.
Applicable to A to I and E to O.
Example: A to I
Every missionaries are evangelists.
Some non-missionaries are non-evangelists.
E to O
No criminals are good men.
Some non-criminals are not non-good men.