For which of the following forms of categorical propositions contraposition is…
2022
For which of the following forms of categorical propositions contraposition is valid?
(A) Some S is P
(B) Some S is not P
(C) No S is P
(D) All S is P
Choose the correct answer from the options given below:
Answer: D. B, C and D only — ConceptContraposition replaces the subject and predicate with their complements and reverses their order. In traditional categorical logic it can be tested by…
- A.
A, C and D only
- B.
A, B, C and D
- C.
A, B and C only
- D.
B, C and D only
Attempted by 5 students.
Show answer & explanation
Correct answer: D
Concept
Contraposition replaces the subject and predicate with their complements and reverses their order. In traditional categorical logic it can be tested by the obvert–convert–obvert sequence.
The A and O forms support contraposition directly. The E form supports it only by limitation, whereas the I form does not support it.
Application
Map the statements to standard forms: A is I (Some S is P), B is O (Some S is not P), C is E (No S is P), and D is A (All S is P).
Apply the rule: O and A admit direct contraposition; E admits contraposition by limitation; I does not admit contraposition.
Thus the forms named by B, C, and D are the ones for which contraposition is available under the traditional rule used here.
Contrast
A, C and D only includes the I form and omits the O form.
A, B, C and D includes the I form along with the three supported forms.
A, B and C includes the I form and omits the A form.
Result
Therefore, B, C and D only is the required combination.