As applied to conjunctive propositions conversion by contraposition assumes the following forms-

Of these two kinds of conjunctive syllogisms we will first take that which consists throughout of conjunctive propositions.

The Conjunctive Syllogism has one or both premisses conjunctive propositions: but if only one is conjunctive, the other must be a simple one.

Then they add a negation of conjunctive propositions; as, "It is not both this and that; but it is this; therefore it is not that."

Conjunctive propositions may assume any of the four forms, A, E, I, O, as follows-