Question

Use the modern square of opposition to write both a valid and an invalid argument, each with a single premise in standard form( A,E, I or O) followed directly by a conclusion in standard form (A,E,I, or O)

Answer 1

A modern square of opposition represents contradictory pairs of 4 different types of categorical propositions according to Boole? A-O are contradictory relation statements which means that they will have opposite truth values (if Ais said to be true it follows that O will be false) . Similarly, E-I are contradictory relation statements.

Thus, an instance of a valid argument would be :

Some people are happy

All those who are happy are people

Therefore, it is false that no people are happy

An instance of invalid argument( with existential fallacy) according to modern square of oppposition is:

All people are happy

Therefore, some people are happy