Subject: LOGIC Professor: Mr. Vincent Navarro

1. This is a kind of education which results from
a formulation of a new proposition whose subject
term is the contradictory of the predicate term in the
original proposition.
In principle, contraposition is a product of
both conversion and obversion . Thus like conversion
, contraposition involves an interchange of the
subject and predicate terms, and like obversion , it
involves either the use or removal of negatives which
affects the copula and the terms.

2. We can immediately see that there are two types of
Contraposition. They are Partial or Simple and
Complete.
Partial Contraposition consists the formulation of a
new proposition (contraposit) through the following:
a. Its (contraposit) subject is the contradictory of the
predicate term of the original proposition
(contraponend),
Ex. (Contraponend) All whales are mammals. (A) to
Su Pp
(Contraposit) No non-mammals are whales. (E)
Su Pu

3. b. The quality of the contraponend is changed in the
contraposit; and
Ex. (Contraponend) No fishes are dogs. (E) to
Su Pu
(Contraposit) Some non-dogs are fishes. (I)
Sp Pp
c. The predicate term in the “A” proposition is changed
to “E”, while “E” proposition to “I”, and an “O”
proposition to “I”.
Ex.(Contraponend) Some students are not studios.(O) to
Sp Pu
(Contraposit) Some non-studious are not non-students.(E)
Sp Pp

4. Complete Contraposition. a new proposition
(contraposit) is formulated through the following steps:
a. The subject term in the contraposit is the
contradictory of the predicate term in the
contraponend ,
b. The quality of the contraponend is not changed in
the contraposit ; and
c. The predicate term in the contraposit is the
contradictory of the subject term in the
contraponend.
In complete contraposition, an “A” proposition is
changed to A, then E to O, and O to O.

5. 1. (Contraponend) All whales are mammals. (A) to
Su Pp
(Contraposit) All non-mammals are non-whales.(A)
Su Pp
2. (Contraponend) No fish is a dog. (E) to
Su Pu
(Contraposit) Some non-dog is not a non-fish. (O)
Sp Pu
3. (Contraponend) Some students are not studious.(O) to
Sp Pu
(Contraposit) Some non-studious are not students.(O)
Sp Pu