logical thinking discussion 8
Introduction to Logic and Critical Thinking
Module 8: Term Logic
Discussion Activity
1. Identify each of the following propositions as having the form A, E, I, or O, then place it in standard categorical form. In each case, clearly indicate the subject and the predicate terms.
2. Draw a Venn diagram representing each of the propositions.
3. For each proposition state whether it has existential import a) according to the ancient (Aristotelian) interpretation, and b) according to the modern (hypothetical) interpretation.
4. For each proposition, construct its converse, contrapositive, and obverse. State whether each of converse, contrapositive, and obverse is logically equivalent to the original proposition.
1. Only if something is an animal is it a panda.
A
All Panda are animal.
Subject – Panda ( P )
Predicate – Animal (A)
Venn diagram will be uploaded separately
Existential Import:
Ancient: yes
Modern: No
Converse: All animal are panda ( Not Valid)
Contrapositive: All non-animal are non-panda. ( Valid)
Obverse: No Panda are non-Animal ( Valid)
2. Only brave people are soldiers.
A
All soldiers are brave people
Subject – soldiers ( S )
Predicate – brave people (P)
Venn diagram will be uploaded separately
Existential Import:
Ancient: yes
Modern: No
Converse: All brave people are soldiers. ( Non-Valid)
Contrapositive: All non-brave people are non-soldiers ( Valid)
Obverse: No Soldiers are non-brave people ( Valid)
3. The only way out of this situation is by talking it out.
No AEIO form because it is all verb?
4. Something is a woodpecker only if it is a bird.
A
All woodpecker are a bird
Subject – woodpecker (W)
Predicate – bird (B)
Venn diagram will be uploaded separately
Existential Import:
Ancient: yes
Modern: No
Converse: All bird are woodpecker ( Non-Valid)
Contrapositive: All non-bird are non-woodpecker ( Valid)
Obverse: No woodpecker are non-bird ( Valid)
5. If
Module 8: Term Logic
Discussion Activity
1. Identify each of the following propositions as having the form A, E, I, or O, then place it in standard categorical form. In each case, clearly indicate the subject and the predicate terms.
2. Draw a Venn diagram representing each of the propositions.
3. For each proposition state whether it has existential import a) according to the ancient (Aristotelian) interpretation, and b) according to the modern (hypothetical) interpretation.
4. For each proposition, construct its converse, contrapositive, and obverse. State whether each of converse, contrapositive, and obverse is logically equivalent to the original proposition.
1. Only if something is an animal is it a panda.
A
All Panda are animal.
Subject – Panda ( P )
Predicate – Animal (A)
Venn diagram will be uploaded separately
Existential Import:
Ancient: yes
Modern: No
Converse: All animal are panda ( Not Valid)
Contrapositive: All non-animal are non-panda. ( Valid)
Obverse: No Panda are non-Animal ( Valid)
2. Only brave people are soldiers.
A
All soldiers are brave people
Subject – soldiers ( S )
Predicate – brave people (P)
Venn diagram will be uploaded separately
Existential Import:
Ancient: yes
Modern: No
Converse: All brave people are soldiers. ( Non-Valid)
Contrapositive: All non-brave people are non-soldiers ( Valid)
Obverse: No Soldiers are non-brave people ( Valid)
3. The only way out of this situation is by talking it out.
No AEIO form because it is all verb?
4. Something is a woodpecker only if it is a bird.
A
All woodpecker are a bird
Subject – woodpecker (W)
Predicate – bird (B)
Venn diagram will be uploaded separately
Existential Import:
Ancient: yes
Modern: No
Converse: All bird are woodpecker ( Non-Valid)
Contrapositive: All non-bird are non-woodpecker ( Valid)
Obverse: No woodpecker are non-bird ( Valid)
5. If