Logical Deduction - Study Mode
[#86] Statements : No man is sky. No sky is road. Some men are roads. Conclusions : I. No road is man. II. No road is sky. III. Some skies are men. IV. All roads are men.
Correct Answer
None follows
Explanation
Solution: II is the converse of the second premise and so it holds. No man is sky. No sky is road. Since both the premises are negative, no definite conclusion follows. No man is sky. Some men are roads. Since one premise is particular and the other negative, the conclusion must be particular negative and should not contain the middle term. So, it follows that 'Some roads are not skies'. No sky is road. Some men are roads. As discussed above, it follows that 'Some men are not skies'. Hence, only II follows.
[#87] Statements : All buildings are windows. No toys is building. Some tigers are toys. Conclusions : I. Some tigers are buildings. II. Some windows are tigers. III. All toys are tigers. IV. Some windows are toys.
Correct Answer
(A) None follows
Explanation
Solution: No toy is building. All buildings are windows. Since the middle term 'buildings' is distributed twice and one premise is negative, the conclusion must be particular negative and should not contain the middle term. So, it follows that 'Some windows are not toys'. Some tigers are toys. No toy is building. Since one premise is particular and the other premise is negative, the conclusion must be particular negative and should not contain the middle term. So, it follows that 'Some tigers are not buildings'.
[#88] Statements : Some papers are cats. All cats are bats. No bat is horse. Conclusions : I. Some papers are horses. II. No horse is cat. III. Some bats are papers. IV. All papers are bats.
Correct Answer
(B) Only II and III follow
Explanation
Solution: Some papers are cats. All cats are bats. Since one premise is particular, the conclusion must be particular and should not contain the middle term. So, it follows that 'Some papers are bats'. III is the converse of this conclusion and so it holds. All cats are bats. No bat is horse. Since both the premises are universal and one premise is negative, the conclusion must be universal negative and should not contain the middle term. So, it follows that 'No cat is horse'. II is the converse of this conclusion and so it holds. Some papers are bats. No bat is horse. Since one premise is particular and the other negative, the conclusion must be particular negative and should not contain the middle term. So, it follows that 'Some papers are not horses'.
[#89] Statements : Some dedicated souls are angels. All social workers are angels. Conclusions : I. Some dedicated souls are social workers. II. Some social workers are dedicated souls.
Correct Answer
(D) Neither I nor II follows
Explanation
Solution: The first premise is an I type proposition. So, the middle term 'angels' forming the predicate is not distributed. The second premise is an A type proposition. So, the middle term 'angels' forming the predicate is not distributed. Since the middle term is not distributed even once in the premises, no definite conclusion follows.
[#90] Statements : No gentleman is poor. All gentlemen are rich. Conclusions : I. No poor man is rich. II. No rich man is poor.
Correct Answer
(D) Neither I nor II follows
Explanation
Solution: The first premise is an E-type proposition, So, the middle term 'gentleman' forming the subject is distributed. The second premise is an A-type proposition. So, the middle term 'gentlemen' forming the subject is distributed. Since the middle term is distributed twice, the conclusion cannot be universal. Since one premise is negative, the conclusion must be negative. Thus, it follows that 'Some rich men are not poor'. Thus, neither I nor II follows.