작성일 : 07-06-23 18:48
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토플배경지식 (독해1반 ) dedutive reasoning
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글쓴이 :
이선미 (210.♡.253.218)
 조회 : 2,930  추천 : 0
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토플배경지식
Perhaps the simplest example of a valid deduction is logical inference. Logical inference relies on an axiomatic framework of several ground rules, such as
P → Q
P
⊢ Q
(If P, then Q; P; Therefore, Q - also known as modus ponens), and
P
⊢ ~(~P)
(If P is true, P cannot be false - also known as the law of noncontradiction).
Once the axioms are accepted as true, conclusions may follow from premises by synthesising them into syllogisms. A well-known type is the categorical syllogism, which reaches a conclusion through the synthesis of a major premise, which asserts a universal truth regarding the relationship between two properties P and Q, and a minor premise, which asserts a connection between some entity Z and either P or Q. Through the universal relationship between P and Q, Z's relationship with one of them is deduced to necessitate its relationship with the other. e.g.
All men are mortal (major premise),
Socrates is a man (minor premise),
It follows that Socrates is mortal.
Note that replacing "mortal" with any nonsensical property like "purple-skinned" will not affect the validity of the argument: intuitively, one might deny the major premise or the conclusion; yet anyone accepting the premises must accept the conclusion.
Another body of knowledge that relies exclusively on deductive reasoning is mathematics. Though some areas of mathematics deal with uncertainties (notably probability theory), mathematical thought only concerns itself with what can certainly be known about these uncertainties by deduction
http://en.wikipedia.org/wiki/Deductive_reasoning
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