Term
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Definition
| An argument is a set of propositions such that the truth of one (called "the conclusion") is supposed to be supported by the truth of the others (called "the premises") |
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Term
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Definition
| A proposition is the conclusion of an argument if and only if it functions in that argument as the proposition whose truth is supposed to be supported by the arguments premises. |
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Term
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Definition
| A proposition is a premise of an argument if and only if it functions in that argument as a proposition whose truth is supposed to give support to the truth of that arguments conclusion. |
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Term
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Definition
| An argument is deductive if and only if it supposes that is the premises of the argument were true, then its conclusion would have to be true. |
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Term
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Definition
| A deductive argument is valid if and only if it is impossible for the premise to be true and the conclusion false, i.e., if the premises of the argument were true, then the conclusion would have to be true. |
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Term
| Invalid Deductive Argument |
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Definition
| A deductive argument is invalid if and only if it is possible for the premises to be true and the conclusion false. |
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Term
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Definition
| A deductive argument is sound if and only if it is both valid and all its premises are actually true. |
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| Unsound Deductive Argument |
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Definition
| A deductive argument is unsound if and only is it is either invalid or has at least one actually false premise. |
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Term
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Definition
| An argument is inductive if and only is its conclusion is supposed to be made more likely to be true than to be false given the truth of its premises. |
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Term
| Strong Inductive Argument |
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Definition
| An inductive argument is strong if and only if the argument is such that is the premises of the argument were true, the conclusion would be more likely to be true than to be false. |
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Term
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Definition
| An inductive argument is weak if and only if the argument is such that if the premises of the argument were true, then the conclusion would be less likely (or no more likely) to be true than to be false. |
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Term
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Definition
| An inductive argument is good if and only if it is both strong and all its premises are actually true. |
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Term
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Definition
| An inductive argument is bad if and only if it is either weak or has at least one actually false premise. |
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Term
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Definition
| An argument is good if and only if it is either a sound deductive argument or a good inductive argument. |
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Term
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Definition
| An argument is a bad argument is and only if it is an argument such that it either has at least one actually false premise, or even were all its premises are actually true, its conclusion is no more likely to be true than to be false. |
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Term
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Definition
| A proposition is that aspect of language which can be true or false. |
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Term
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Definition
| A law of logic states a condition that must hold before any proposition could possibly have a truth value. |
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Term
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Definition
| Each proposition is either true or false. |
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Term
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Definition
| No proposition is both true and false. |
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Term
| Rhetorically Effective Argument |
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Definition
| An argument is rhetorically effective if and only if it typically succeeds in persuading its audience of the truth of its conclusion. |
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Term
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Definition
| A use of rhetoric is an instance of content propaganda if and only if it tries to deceive us that false propositions are true and that true propositions are false. |
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Term
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Definition
| A use of rhetoric is an instance of vocabulary propaganda if and only if it tries to deceive us by distorting the meanings of words of phrases so as to make it unclear which propositions sentences are expressing. |
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Term
| Truth Functional Operator and Connective* |
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Definition
| An expression is a truth functional operator or a truth functional connective if and only if it functions to construct compound propositions such that the truth values of those compound propositions depend solely on the truth values of their component propositions. |
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Term
| Rule for Logical Negation |
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Definition
The logical negation of a proposition is true if and only if the proposition is false, and the logical negation of a proposition is false if and only if the proposition is true.
(It is not the case that P) |
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Term
| Rule for Logical Conjunction |
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Definition
A conjunction is true if and only if both conjuncts are true, otherwise the conjunction is false.
(P&Q) |
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Term
| Rule for Inclusive Disjunction |
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Definition
An inclusive disjunction is false only when both its disjuncts are false; and inclusive disjunction is true otherwise.
(P v Q) |
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Term
| Rule for Exclusive Disjunction |
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Definition
An exclusive disjunction is true if and only if exactly one of its disjuncts is true, while the exclusive disjunction is false if both its disjuncts are tye and the exclusive disjunction is false if both disjuncts are false.
(P exclusive-or Q) |
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Term
| Rule for Truth Functional Conditionals |
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Definition
A truth functional conditional is false if and only if its antecedent is true and its consequent is false, otherwise the truth functional conditional is true.
(P -> Q) |
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Term
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Definition
| A state of affairs or event S is a sufficient condition for a state of affairs or event N if and only if the occurrence of S is enough for N to occur. |
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Term
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Definition
| A state of affairs or event N is a necessary condition for a state of affairs or even S if and only if N must occur for S to occur |
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Term
| Rule for Truth Functional Biconditionals |
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Definition
A truth functional biconditional is true if and only if the component propositions it connects have the same truth value, otherwise it is false.
(P <-> Q) |
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Term
| Logical Relation Between Propositions |
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Definition
| Given a set of propositions, the propositions are logically related if and only if the truth value of any one proposition in the set depends on the truth values of the others. |
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Term
| Logically Inconsistent Propositions |
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Definition
| Two propositions are logically inconsistent if and only if it is not possible for all its members to be true. |
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Term
| Contradictory Propositions |
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Definition
| Two propositions are contradictories if and only if it is not possible for both propositions to be true and it is not possible for both propositions to be false. |
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Term
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Definition
| Two propositions are contraties if and only if it is not possible for both propositions to be true while it is possible for both propositions to be false. |
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Term
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Definition
| A proposition P is a contradiction if and only if it is not possible for that proposition to be true. |
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Term
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Definition
| A proposition P is a tautology if and only if it is impossible for that proposition to be false. |
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Term
| Logically Consistent Propositions |
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Definition
| A set of propositions is logically consistent if and only if it is possible for all the members of that set to be true. |
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Term
| Contingently Related Propositions |
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Definition
| Two propositions are contingently related if and only if the truth value of one does not depend on the truth value of the other. |
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Term
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Definition
| A proposition P is contingent if and only if it is neither necessarily true not necessarily false. |
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Term
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Definition
| A proposition P logically implies another proposition Q if and only if it is impossible for P to be true and Q false. |
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Term
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Definition
| A proposition Q is a logical consequence of another proposition P if and only if P implies Q. |
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Term
| Logically Equivalent Propositions |
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Definition
| Two propositions are logically equivalent if and only if it is not possible for one proposition to be true while the other is false. |
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Term
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Definition
| The premises of an argument are dependent premises if and only if they are supposed to be taken together in support of the conclusion |
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Term
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Definition
| The premises of an argument are independent premises if and only if each premise (or set of premises) is supposed to support the conclusion |
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Term
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Definition
| A proposition is an intermediate conclusion if and only if it functions both as the conclusion of one argument and the premise of another argument. |
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