Square of opposition
The square of opposition is a diagram that illustrates the logical relationships between four types of categorical propositions: universal affirmative (A), universal negative (E), particular affirmative (I), and particular negative (O). It originated with Aristotle and shows how the truth value of one proposition can be used to determine the truth value of another based on relationships like contradiction (Contradictions are statements that cannot both be true or both be false; they always have opposite truth values, such as "it is raining" and "it is not raining), contrariety (Contraries are statements that cannot both be true, but can both be false, such as "the shirt is red" and "the shirt is green," because the shirt could be blue), and subcontrariety (Subcontrariety is a logical relationship between two propositions/statements where they can both be true but cannot both be false. Example: "Some cats are black" (True) and "Some cats are not black" (True) – both statements hold, but if one were false. For example, "Some cats are not black" is false, meaning all cats are black, the other would still be true.).[1]
External links
- Square of Opposition, Internet Encycylopedia of Philosophy
- What is the square of opposition, AI