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Unformatted text preview: Categorical Logic I Contradictories Validity for Arguments Containing Categorical Propositions Immediate Inferences The Theory of the Syllogism Contradictories Contradictories are two propositions that cannot be true simultaneously. When people say, “That’s a contradiction,” they mean (whether they know it or not) that some argument has two premises, one of which is the negation of the other. When formulating an argument, you want to avoid contradictories. When criticizing an argument, you might want to look for them. Showing an argument’s internal contradictions is one of the most powerful ways to defeat it. On that note, it’s important to remember that only propositions can be contradictory, and a contradiction can only be a relationship between propositions i.e., sets of statements. There can’t be contradictions “in the world,” so to speak, nor can states of a f airs be contradictory. Contradictories Negation of “No S is P ”: Some S is P Contradictories are two propositions that cannot be true simultaneously. When people say, “That’s a contradiction,” they mean (whether they know it or not) that some argument has two premises, one of which is the negation of the other. When formulating an argument, you want to avoid contradictories. When criticizing an argument, you might want to look for them. Showing an argument’s internal contradictions is one of the most powerful ways to defeat it. On that note, it’s important to remember that only propositions can be contradictory, and a contradiction can only be a relationship between propositions i.e., sets of statements. There can’t be contradictions “in the world,” so to speak, nor can states of a f airs be contradictory. Contradictories Negation of “No S is P ”: Some S is P Negation of “All S is P ”: Some S is not P Contradictories are two propositions that cannot be true simultaneously. When people say, “That’s a contradiction,” they mean (whether they know it or not) that some argument has two premises, one of which is the negation of the other. When formulating an argument, you want to avoid contradictories. When criticizing an argument, you might want to look for them. Showing an argument’s internal contradictions is one of the most powerful ways to defeat it. On that note, it’s important to remember that only propositions can be contradictory, and a contradiction can only be a relationship between propositions i.e., sets of statements. There can’t be contradictions “in the world,” so to speak, nor can states of a f airs be contradictory. Contradictories Negation of “No S is P ”: Some S is P Negation of “All S is P ”: Some S is not P Note : “No S is P ” and “All S is P ” are not contradictories....
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This note was uploaded on 03/31/2008 for the course PHIL 1504 taught by Professor Cbhaufe during the Spring '08 term at Virginia Tech.
 Spring '08
 CBHaufe

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