LOGIC

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					LOGIC

DEDUCTIVE
   Vs
INDUCTIVE
        DEDUCTIVE REASONING
• Deductive reasoning works from the more general to the more
  specific. Sometimes this is informally called a "top-down" approach.
• We might begin with thinking up a theory about our topic of
  interest. We then narrow that down into more specific hypotheses
  that we can test.
• We narrow down even further when we collect observations to
  address the hypotheses. This ultimately leads us to be able to test
  the hypotheses with specific data -- a confirmation (or not) of our
  original theories.
• DEDUCTIVE REASONING: Deduction deals more with soundness of
  arguments than "truth".
• Given that their premises are true, the conclusions of deductive
  reasoning must be true.
• For instance, if it is true that all dogs are animals, and if it is true
  that all animals are living things, then it must be true that all dogs
  are living things
• Effort in deduction is spent in determining
  whether arguments are sound.
• Many puzzles involve deductive reasoning.
• Solve this puzzle below. Explain your
  solutions.?
• a) You are marooned on an island, where
  there are only liars and truth-tellers. You
  meet a couple and the husband says, "My wife
  told me that she is a liar.". Is he a liar or a
  truth-teller?
• A liar of course. No one on the island can
  claim themselves to be a liar - if they are
  truth-tellers, it would be a lie, and they
  cannot lie; conversely, if they are liars, it
• A liAr becAuse…if his wife wAs A liAr then
  she would have told her husband she was a
  truth-teller.
• If his wife was a truth-teller she would have
  told her husband she was a truth-teller.
• If the first had happened and the man was a
  truth teller, he would have told you she was
  a truth teller.
• If the second had happened and the man was
  a truth teller, he would have told you she
  was a truth teller.
• If the first had happened and the man was a
  liar, he would have told you she was a truth
  teller.
• And ditto if the second had happened and the
       INDUCTIVE REASONING
• Inductive reasoning works the other way, moving from specific
  observations to broader generalizations and theories
• Informally, we sometimes call this a "bottom up" approach (please
  note that it's "bottom up" and not "bottoms up" which is the kind of
  thing the bartender says to customers when he's trying to close for
  the night!).
• In inductive reasoning, we begin with specific observations and
  measures, begin to detect patterns and regularities, formulate some
  tentative hypotheses that we can explore, and finally end up
  developing some general conclusions or theories.
• Inductive reasoning, by its very nature, is more open-ended and
  exploratory, especially at the beginning.
“NEVER ASSUME ANYTHING…BEWARE OF FAULTY BELIEFS
BUILT ON THE SHAKY GROUND OF FAULTY PERCEPTIONS”

• Francis Bacon …science should be used to explAin the
  world and the universe.
• And, religion should explain faith.
• Bacon advocated the SCIENTIFIC METHOD OF REASONING
  (inductive reAsoning…inductive reAsoning is Also
  called scientific reasoning)
• LOGIC…the wAy we think…hAs been divided into two
  forms of reasoning INDUCTIVE AND DEDUCTIVE
  REASONING.
• Inductive reasoning essentially involves
  generalization.
• After observing a number of examples,
  conclusions are drawn which seem most
  likely.
              Inductive reasoning…another example

• Honey bee hives are dying all across the country.
  This is an actual fact. What is killing them?
• I observe that five hundred of these hives have
  varroa mites. However, the other five hundred hives
  do not have mites.
• I observe, in my very scientific way, that hives with
  mites usually die in a year, but hives without mites
  live.
• I conclude that varroa mites are killing honey bees.
• When an argument claims that the truth of its
  premises make it likely or probable that its
  conclusion is also true, it is said to involve inductive
  reasoning.
• so, frAncis bAcon’s scientific Method involves
  OBSERVATION, MEASUREMENT, EXPERIMENTATION,
  HYPOTHESIS, AND VERIFICATION
• These two methods of reasoning have a very different "feel" to them
  when you're conducting research.

• Inductive reasoning, by its very nature, is more open-ended and
  exploratory, especially at the beginning.

• Deductive reasoning is more narrow in nature and is concerned with
  testing or confirming hypotheses. Even though a particular study may
  look like it's purely deductive (e.g., an experiment designed to test the
  hypothesized effects of some treatment on some outcome), most social
  research involves both inductive and deductive reasoning processes at
  some time in the project.

				
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posted:4/21/2012
language:English
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