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29 Cards in this Set
 Front
 Back
Proposition

• a true or false sentence


Argument

• a series of propositions the complete expression of which is divided into assumptions and conclusions by an inference indicator


Logical Contradiction

• any proposition that is never true, or that is false under any circumstances, no matter what the world happens to be like, or that is true just in case its negation is true


Logical Impossibility

• the truth of a proposition or the occurrence of a condition is logically impossible if and only if the proposition or the adequate description of the state of affairs it proposes involved a logical contradiction


Logical Necessity

• the truth of a proposition or the occurrence of a condition is logically necessary if and only if its falsehood or the nonoccurrence of the state of affairs it proposes is logically impossible


Deductively Valid Argument

• an argument that is such that it is logically necessary that id its assumptions are true, then its conclusions are true, or such that it is logically impossible for its assumptions to be true and its conclusions false


Sound Argument

• a deductively valid argument with only true assumptions


subject term

 subject of the proposition
 Alice is friendly. 

predicate term

 the object of the proposition
 Alice is friendly 

Copula

 Verb of the proposition
 Alice is friendly. 

Assumption

 The ideas from which the conclusion are to follow


Conclusion

 The idea that is supposed to follow from the assumptions


inference indicator

 ‘thus,’ ‘hence,’ ‘therefore,’ etc.


reconstructed argument

1.) If the salmon are running then the river has melted
2.) But the river has not melted 3.) The salmon are not running 

principle of charity

 Requires that whenever possible, we try to reconstruct arguments as deductively valid before criticizing their logical form or content


imagination test for deductive validity

Try to imagine the situation or set of circumstances in which the assumptions of an argument are true and the conclusions false. If you can do so, then there is a strong reason to believe that the argument is deductively invalid; if you cannot do so, then there is a strong reason to believe that the argument is deductively valid


conditional statement

‘ifthen’ statement


antecedent

If P,


Consequent

Then Q


conditional argument

Contains at least one proposition that has an ‘ifthen’ form


modus ponens

If P, then Q
P_______ Q 

modus tollens

If P, then Q
Not Q_______ Not P 

affirming the consequent

If P, then Q
Q_________ P 

denying the antecedent

If P, then Q
Not P_______ Not Q 

Contrapositive

If P, then Q
If not P, then not Q 

hypothethical syllogism

If P, the Q
If Q, then R If P, then R 

disjunctive syllogism

P or Q
Not P Q 

constructive dilemma

P or Q
If P, then R If Q, then R R 

reductio ad absurdum

P
Q_____ R and not R NotP 