For which of the following forms of categorical proposition is conversion valid?

1.Some S is P

2.Some S is not P

3.No S is P

4.All S is P

A1, 2, 3 & 4

B1, 3 & 4 only ✓ Correct

C2, 3 & 4 only

D1, 2 & 4 only

Correct answer: (B) 1, 3 & 4 only

Explanation

Conversion is valid for the I, E and A forms, that is items 1, 3 and 4.

In I, "Some S is P", both terms are undistributed, so "Some P is S" follows.

In E, "No S is P", both terms are distributed, so "No P is S" follows.

In A, "All S is P", conversion is valid by limitation, giving "Some P is S".

These three respect the rule that no term may be distributed in the converse unless distributed in the original.

Want more like this? Create a free account to practise a full test, track your progress, and get spaced-repetition review.