If the statement "Some animals are birds" is given as false then which of the following statements can be immediately inferred to be false?
All animals are birds.
Concept: On the Square of Opposition, the universal affirmative (A) 'All S are P' and the particular affirmative (I) 'Some S are P' stand in a relation of subalternation: the truth of A implies the truth of I. Equivalently, if I is false, then A must also be false, because a universal claim cannot hold when even its weaker particular version fails.
Working: We are told 'Some animals are birds' (an I-proposition) is false. Since 'All animals are birds' (the corresponding A-proposition) would, if true, force 'Some animals are birds' to be true, the falsity of the I-statement immediately makes the A-statement false as well. Therefore 'All animals are birds' can be immediately inferred to be false.
Why the other choices are wrong:
'No animals are birds' is the contradictory of the false I-statement, so it must be true, not false.
'Some animals are not birds' is the E/O-region result that also follows as true when 'Some animals are birds' is false, so it cannot be the false one.
'Some birds fly' involves an entirely different predicate (flying) and is not logically connected to the given proposition, so its truth value cannot be inferred at all.
Takeaway: If a particular affirmative is false, its corresponding universal affirmative is necessarily false.
Correct answer: All animals are birds.
Similar Questions
Which of the following is contrary to the statement "No mammals are birds"?
Which of the following propositions can be directly inferred from the statement - "All mammals are four-legged animals?
Which of the following statements are contradictory to each other?
A. All objects are perishable.
B. Some objects are not perishable.
C. Some objects are perishable.
D. No objects are perishable.
Choose the most appropriate answer from the options given below:
If the statement 'No men are honest' is given as false, then which of the following could be immediately inferred from it?
A. 'All men are honest' is true
B. 'All men are honest' is undetermined
C. 'Some men are not honest' is true
D. 'Some men are honest' is true
Choose the correct answer from the options given below:
Given below are two statements
Statement I: Contrary statements are so related that if one of them is true, the other must be false.
Statement II: Contrary statements cannot both be false.
In light of the above statements, choose the correct answer from the options given below :If the proposition ‘domestic animals are hardly ferocious’ is taken to be false, which of the following proposition/propositions can be claimed to be certainly true? Select the correct code:
Propositions:
(a) All domestic animals are ferocious.
(b) Most of the domestic animals are ferocious.
(c) No domestic animal is ferocious.
(d) Some domestic animals are non-ferocious.
Code:
Given below are four statements. Among them two are related in such a way that they can both be true but they cannot both be false. Select the code that indicates those two statements:
Statements:
(a) Honest people never suffer.
(b) Almost all honest people do suffer.
(c) Honest people hardly suffer.
(d) Each and every honest person suffers.
Code:
Among the following propositions two are related in such a way that they cannot both be true but can both be false. Select the code that states those two propositions.
Propositions:
(a) Every student is attentive.
(b) Some students are attentive.
(c) Students are never attentive.
(d) Some students are not attentive.
Codes:
If proposition 'some milk is curd' is taken to be true, then which of the following propositions can be false?
When subject and predicate of both the premises is same but they differ only in quantity, it is known as:
Important Questions from Classical Square of Opposition
Which of the following statements are so related that they can not both be true but could both be false?
A. All Biologists are outstanding teachers.
B. Some Biologists are outstanding teachers.
C. No Biologists are outstanding teachers.
D. Some Biologists are not outstanding teachers.
Choose the correct answer from the options given below:
- Which of the following propositions are so related that they can neither be true together nor can they be false together?
A. All printers are computer peripherals.
B. Some computer peripherals are printers.
C. Some printers are not computer peripherals.
D. No printers are computer peripherals.
Choose the correct answer from the options given below: - Which of the following statements contradict each other ?
A. All ducks are birds.
B. Some ducks are birds.
C. Some ducks are not birds.
D. No ducks are birds.
Choose the most appropriate answer from the options given below : - If the statement "No birds are animals" is given as false, which of the following statements can be inferred to be true ?
A. Some animals are not birds.
B. Some birds are not animals.
C. Some animals are birds.
D. Some birds are animals.
Choose the most appropriate answer from the options given below : - Which of the following statements are sub-contraries?
A. All sparrows are birds.
B. No sparrows are birds.
C. Some sparrows are birds.
D. Some sparrows are not birds.
Choose the correct answer from the options given below:
