Use the rule every human is an animal. For any object define:
A: It is not human.
B: It is an animal.
For a human: A false, B true.
For a horse: A true, B true.
For a stone: A true, B false.
Both false would mean something is human but not an animal, contradicting the stated rule. This gives an especially transparent additional example of exclusion of joint falsehood.
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Conditional Propositions: Connectives, Disjunctions and Their Main Kinds
Use the rule every human is an animal. For any object define:
A: It is not human.
B: It is an animal.
For a human: A false, B true.
For a horse: A true, B true.
For a stone: A true, B false.
Both false would mean something is human but not an animal, contradicting the stated rule. This gives an especially transparent additional example of exclusion of joint falsehood.