In the classical square of opposition, if the proposition 'No S is P' is given as false, then which of the following could be immediately inferred from it?

1.'Some S is not P' is true

2.'All S is P' is undetermined

3.'Some S is not P' is undetermined

4.'Some S is P' is true

5.'Some S is not P' is false

A2, 4 and 5 only

B1, 2 and 4 only

C1, 4 and 5 only

D2, 3 and 4 only ✓ Correct

Correct answer: (D) 2, 3 and 4 only

Explanation

From the false E, 'Some S is P' is true, while 'All S is P' and 'Some S is not P' stay undetermined.

The proposition given false is E type, 'No S is P'.

Its contradictory is I, 'Some S is P', so I must be true.

A true particular affirmative cannot fix its universal, so 'All S is P' remains undetermined.

It also leaves its subcontrary open, so 'Some S is not P' stays undetermined too.

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