Contradiction occurs when one proposition affirms precisely what another denies, with matching relevant circumstances, so that one is true exactly when the other is false.
Example: At the same time and in the same respect, 'This door is open' and 'This door is not open.'
The textbook identifies eight required identities to prevent the appearance of contradiction where the assertions actually differ in meaning.
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The definition of contradiction
Contradiction and the Eight Conditions
Contradiction occurs when one proposition affirms precisely what another denies, with matching relevant circumstances, so that one is true exactly when the other is false.
Example: At the same time and in the same respect, 'This door is open' and 'This door is not open.'
The textbook identifies eight required identities to prevent the appearance of contradiction where the assertions actually differ in meaning.