Option 2 : Contradictories

The standard form of categorical proposition having the same subject term and predicate term but may differ from each other in quality or quantity or both. Such differing has been called opposition. The term opposition is used when there is no apparent disagreement between the propositions.

**Types of Opposition:**

**Contradictories:**The standard form of a categorical proposition that has the same subject and predicate term but differs from each other in both quantity and quality. Two propositions are contradictories if one is denial or negation of the other if they can’t be true or can’t be both false.**Example:**All republics are grateful. Some republics are not grateful.**Contraries:**Two propositions are said to be contraries if they can’t both be true, and the truth of one entails of the truth of the other. i.e. both can’t be true and both can’t be false. If either of these propositions is true, then the other must be false.**Example:**All artists are dreamers. No artist is dreamer.**Sub-contraries:**If a particular proposition having the same subject and predicate terms but differing in quality, one affirming the other denying. Two propositions are said to be sub-contraries if they can’t both be false although both may be true.**Example:**Some cars are vehicles. Some cars are not vehicles.**Subalternation:**It is the opposition between a universal proposition and its corresponding particular proposition. In the corresponding proposition, the universal proposition is called superaltern and the particular proposition is called subaltern. These propositions have the same subject and predicate term and agree in quality. Both are affirming or both denying but differ in quantity. On universal and the other particular.**Example:**No hens are birds Some hens are not birds**The square of opposition:**There are four ways in which propositions may be opposed as contradictories, contraries, sub-contraries, subalterns and superaltern. These are represented using a diagram called the square of opposition.