What is an argument?

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What is an argument?

• http//www.youtube.com/watch?vkQFKtI6gn9Y
• An argument is a connected series of statements
  to establish a definite proposition
• When trying to persuade ? USE AN ARGUMENT
• Giving reasons to support a conclusion
• Parts of an argument
• PREMISES propositions taken as support or proof
• CONCLUSION the proposition being proven or
  supported

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Consider this example

• Capital punishment should not be used because
  wrongly convicted people will be executed by
  mistake and this is totally unacceptable.
• (What is the conclusion? What are the supports?)
• P1 If capital punishment is used, then wrongly
  convicted people will be executed by mistake.
• P2 The execution of wrongly convicted people is
  totally unacceptable.
• C Capital punishment should not be used.
• (P premise, C conclusion)

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Conclusion-Indicators Premise-Indicators

• Conclusion-indicators
• Therefore
• Hence
• Thus
• So
• Consequently
• It follows that
• We may infer that
• We may conclude that

• Premise-indicators
• Since
• Because
• Given that
• Assuming that
• Inasmuch as
• For the reason that

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Deductive Arguments

• A DEDUCTIVE argument is either valid or invalid
• VALID deductive argument
• The conclusion is logically entailed in, or
  necessarily follows from the premises
• (the form of the argument works the conclusion
  follows the premises.
• THERE IS INFERENCE the conclusion is CONNECTED
  to the premises)
• LOGICAL ENTAILMENT
• Occurs when the conclusion must be true given
  that the premises are true.
• INVALID deductive argument
• An argument is offered as valid, but the
  conclusion is not logically entailed in the
  premises.
• An argument could have true premises, and yet the
  conclusion is false
• (there is NO INFERENCE the conclusion is NOT
  CONNECTED to the premises)

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Deductive Reasoning

• Begins with a UNIVERSAL rule, truth, or
  generalize statement.
• Leads to a particular/specific instance of the
  universal rule.
• In valid deductive reasoning / arguments,
  therefore, the conclusions are NECESSARILY,
  DEFINITELY OR CERTAIN as true.
• All men are mortal.
• Socrates is a man.
• Socrates is mortal.

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Inductive Arguments

• An argument where the conclusion is PROBABLY
  true.
• (Inductive reasoning proceeds from specific /
  particular instances to develop a generalization
  or universal rule)
• Its likely more helpful to judge inductive
  arguments as strong or weak (not valid or invalid)

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Inductive Arguments

• The basic assumption present and past
  observations lead to a general statement, and
  will continue to follow that pattern in the
  future.
• Notice since we havent observed ALL the
  possibilities, our rule is only PROBABLE
• (Consider David Humep. 32)

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Abductive Arguments

• Arguments where the conclusion is a best guess
  that is to be judged to the most plausible
  explanation among competing alternatives, given
  that the premises are true.
• The term, abductive comes from Charles Sanders
  Pierce (19th C. American philosopher)

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Comparing the Three

• Deductive
• If premises true ? conclusion true
• Impossible for all premises to be true
  conclusion false
• Contradictory for premises to be true and
  conclusion false
• If conclusion false, at least one of the premises
  must be false
• Inductive
• If premises true ? conclusions probably
  true
• unlikely that if premises are true, conclusion
  false
• conclusion can be false while all premises
  true
• Abductive
• If premises true ? conclusion judged a good
  candidate, among other possibilities, for
  being true
• Ockhams razor the basic assumption
• conclusion can be false while premises true

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Reasoning Bias

• Francis Bacon (1561-1626)
• Focused on the utility of scientific knowledge
  for enabling us to know better
• Novum Organon (New Instrument) departure from
  Aristotles Organon
• Bacon emphasized observation and induction
• Aristotle preferred deduction, knowledge for its
  own sake (not utility)

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Idols of the Mind

• We strive to be impartial, objective
  open-minded
• But, we can be swayed from reasoning clearly
  correctly by distortions
• Bacon called these distortions IDOLS, i.e.,
  revered false appearances
• Idols of
• The tribe
• The cave
• The marketplace
• The Theatre

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Idols of the Tribe

• Biases common to all people that are inherent in
  human nature and the very tribe or race of men,
  for mans sense is falsely asserted to be the
  standard of things.
• Human understanding like a false mirror
• We should be wary of our sense perception for our
  senses often deceive us.

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Idols of the Cave

• Everyone has a cave or den of his own, which
  refracts and discolours the light of nature,
  owing either to his own proper and peculiar
  nature, or his education
• Individual habits of thought, personal
  experiences, our own education, interests
• The distortion is peculiar to each individual
  person

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Idols of the Marketplace

• Our thoughts are traded by the use of words in a
  conversational marketplace
• The idols of the marketplace sloppy use of
  words,
• i.e., words that are ill-defined, ambiguous
• the ill and unfit choice of words wonderfully
  obstructs the understanding.

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Idols of the Theatre

• Bacon cautions against blind acceptance of
  established systems of knowledge,
• Like theatrical productions that present mere
  fiction
• We need to critically examine the foundations of
  our philosophical, scientific, theological
  systems
• Uncritical acceptance of systems of thought
  idols of the theatre

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Consider these distortions

• Stereotyping other people cultures
• Self-centred thinking, our own interests colour
  our interpretations
• Peer pressure, pressure for social conformity, we
  have a powerful psychological need to be liked
  accepted by others
• Confirmation bias, the tendency to accept
  information that confirms what we already think
  and disregard information that threatens not to
  confirm what we already think