“This object is white” and “This object is black” cannot both hold in the same respect, but both may be false if the object is red. That is not contradiction as defined here.
“This object is white” and “This object is not white” negate precisely the same property. With the relevant conditions held fixed, exactly one is true.
Distinction: opposed positive predicates may both fail, whereas an affirmation and its exact negation cannot. This comparison clarifies the textbook’s definition.
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Contradiction: Definition, Conditions and Application to Propositions
“This object is white” and “This object is black” cannot both hold in the same respect, but both may be false if the object is red. That is not contradiction as defined here.
“This object is white” and “This object is not white” negate precisely the same property. With the relevant conditions held fixed, exactly one is true.
Distinction: opposed positive predicates may both fail, whereas an affirmation and its exact negation cannot. This comparison clarifies the textbook’s definition.