Test 2 Logical Reasoning

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Test 2 Logical Reasoning
2012-10-08 21:56:49

Chap 1 & 2
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  1. Enthymemes
    Arguments missing a premise or conclusion; usually left out b/c speaker thinks listener will be able to fill in
  2. Principle of charity
    Given 2 or more possible interpretations, apply the most plausible (whenever you see that one interpretation is stronger or makes more sense than another, then that is the one you ought to choose)
  3. Good Argument
    -given the premises, the conclusion follows from them either with deductive validity or inductive strength, and the premises are true
  4. Deductive arguments that follow necessarily from the premises and has a true conclusion is considered to be valid and sound; if the premises of a deductive argument are true and conclusion follows necessarily it is still considered valid but if the conclusion is not necessarily true then it would be unsound; deductive arguments can also be considered invalid if one or more premises are not true
  5. Inductive arguments are varying in strength from strong (100-90%), moderate (89-51), weak (=50 or >); if inductive argument is strong or moderate it can be cogent or not cogent, for it to be cogent it needs to have true premises and is a moderate or strong argument, conclusion follows from premises; the strong or moderate inductive argument could be not cogent if has at least one false premise
  6. Valid/logical forms:

    -Disjunctive syllogism
    -Modus Ponens
    -Modus tollens
    • -Barbara
    • -All A are B
    • All B are C
    • All A are C

    • -Disjunctive syllogism
    • -A or B
    • Not A
    • B

    • -Modus Ponens
    • -If A then B
    • A
    • B

    • -Modus tollens
    • -If A then B
    • Not B
    • Not A
  7. Invalid Logical Forms:

    -Fallacy of denying the antecedent
    -Fallacy of affirming the consequent
    -Fallacy of undistributed middle
    • -Fallacy of denying the antecedent
    • -If A then B
    • Not A
    • Not B

    • -Fallacy of affirming the consequent
    • -If A then B
    • B
    • A

    • -Fallacy of undistributed middle
    • -All A are B
    • All C are B
    • All C are A
  8. Empirical statement-
    To verify a statement by experience means that the truth or falsity of the statement is determined by making some sort of observation, having a look at the subject and seeing whether it is as the statement says it is; observations made using the senses; there is that sense that there is something to examine
  9. Nonempirical statements-
    These statements are not verifiable by experience; making observations, doing tests, conducting surveys, and so on, are of no help because these statements do not assert what is found by looking at the world around us; it is not checking the properties of things in the world, it is about our ideas