Square of Opposition complete free course

Example: if given is true then which of following is true

A

E

I

O

Contradictory: A and O, E and I

A and O Both cannot be true or false together means if one is false then other must be true

If A is true then O is false

If O is true then A is false

Should Have same Subject and Predicate

Sub Contraries   I and O Both can be true together but not false together

Contraries   A and E Both cannot be true together but can be false together

1 If the statement ‘all students are intelligent’ is true, which of the following statements are false?

(i) No students are intelligent.

(ii) Some students are intelligent.

(iii) Some students are not intelligent.

(A) (i) and (ii)

(B) (i) and (iii)

(C) (ii) and (iii)

(D) (i) only

2 If the statement some men are cruel’ is false, which of the following statements/statement are/is true ?

(i) All men are cruel.

(ii) No men are cruel.

(iii) Some men are not cruel.

(A) (i) and (iii)

(B) (i) and (ii)

(C) (ii) and (iii)

(D) (iii) only

If the statement ‘some men are cruel’ is false, which of the following statements/statement are/is true ?

(i) All men are cruel.

(ii) No men are cruel.

(iii) Some men are not cruel.

(A) (i) and (iii)

(B) (i) and (ii)

(C) (ii) and (iii)

(D) (iii) only

If the proposition “Vegetarians are not meat eaters” is false, then which of the following inferences is correct? Choose from the codes given below:

1. “Some vegetarians are meat eaters” is true.
2. “All vegetarians are meat eaters” is doubtful.
3. “Some vegetarians are not meat eaters” is true.
4. “Some vegetarians are not meat eaters” is doubtful.

Codes:

(A) 1, 2 and 3

(B) 2, 3 and 4

(C) 1, 3 and 4

(D) 1, 2 and 4

By which of the following proposition, the proposition ‘some men are not honest’ is contradicted?

(A) All men are honest.

(B) Some men are honest.

(C) No men are honest.

(D) All of the above.

If the statement ‘most of the students are obedient’ is taken to be true, which one of the following pair of statements can be claimed to be true?

1. All obedient persons are students.
2. All students are obedient.

III. Some students are obedient.

1. Some students are not disobedient.

Codes :

(A) I & II

(B) II & III

(C) III & IV

(D) II & IV

If the statement ‘some men are honest’ is false, which among the following statement swill be true. Choose the correct code given below:

(i) All men are honest

(ii) No men are honest

(iii) Some men are not honest.

(iv) All men are dishonest.

Codes:

(A) (i), (ii) and (iii)

(B) (ii), (iii) and (iv)

(C) (i), (iii) and (iv)

(D) (ii), (i) and (iv)

Ques for practice  (answers can be more than one option)

1 If ‘Author are great’ is true then which of following will be true

• Some Author are great
• All Author are great
• No Author are great
• Author are hardly great

2 If Some Author are great’ is true then which of following will be true

• All Author are great
• No Author are great
• Author are hardly great
• Most Author are great

3 If ‘Some Author are great’ is false then which of following will be correct

• All Author are great is false
• No Author are great is true
• Author are hardly great is false
• Most Author are great is true

4 If ‘No Author are great’ is false then which of following will be correct

• All Author are great is doubtful
• No Author are great is true
• Author are hardly great is doubtful
• Most Author are great is true

5 If ‘In exam RC hardly easy’, is false then which of following is true

• Exam RC are easy
• Most RC are easy
• Some RC are not easy
• 1, 2
• 2, 3
• 1, 3
•  All above

6 All animal are mammal is true then

• Some animal are mammal is doubtful
• Some animal are mammal is false
• Most animal are mammal is true
• No animal are mammal is true

7 All animal are not mammal is false then

• Some animal are not mammal is doubtful
• Some animal are not mammal is false
• Most animal are mammal is true
• No animal are mammal is true