Induction by Confirmation

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Induction by Confirmation

• Induction can be used to support a hypothesis or
  theory by providing confirming instances of that
  hypothesis or theory.
• When we propose a theory or hypothesis, there are
  certain things that ought to be observed if it is
  actually true (or probable).
• These are called observation statements. If we
  do observe what the theory predicts, then we have
  confirmed the theory.

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Induction by Confirmation

• Induction by Confirmation then has the following
  form
• If h then o
• o
• It is probable that h
• NB similar to the formal fallacy of affirming
  the consequent

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Induction by Confirmation

• E.g. (203)
• If the theory of general relativity is true, then
  it follows that light rays passing near the sun
  will bend.
• During the solar eclipse of 1919 it was observed
  that light rays passing near the sun did bend.
• It is probable therefore that the theory of
  general relativity is true.

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Induction by Confirmation

• When assessing these arguments, ask
• Is the number of confirming instances relatively
  high?
• In general, the more confirming instances the
  better the theory.
• Are there any disconfirming instances?
• Any disconfirming instance refutes the theory.

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Induction by Confirmation

• Disconfirming instances are regarded as
  refutations of a theory because such a refutation
  takes this form
• If h then o
• Not-o
• Therefore not-h
• That is, a disconfirming instances refutes a
  theory because we are dealing with a deductively
  valid argument form Modus Tollens (denying the
  consequent).

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Analogical Reasoning

• Analogical reasoning works by comparing things
  which are similar (analogous) and concluding that
  properties or relations that one thing has must
  also be present in the other.

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Analogical Reasoning

• E.g.,
• Last year I put some fertilizer on my
  strawberries and in the fall got about 20 per
  cent more strawberries. You should do the same
  with your strawberries, since you have the same
  kind of soil. Youll probably get more
  strawberries too.

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Analogical Reasoning

• Analogies compare two cases the subject case,
  and the analogue case.
• The subject case is the case about which we are
  trying to derive a conclusion (fertilizer on your
  soil)
• The analogue case is the case about which we are
  more familiar (fertilizer on my soil).

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Analogical Reasoning

• The conclusion in an analogy makes a claim about
  the subject case, and in particular states that
  the subject case will (probably) have the target
  feature.
• The target feature (increase in strawberry
  production) is the feature that is present in the
  analogue case, and it is being concluded that it
  (probably) is in the subject case.

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Analogical Reasoning

• There are two kinds of analogical arguments
• Analogical Argument by Properties
• Analogical Argument by Relations

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Analogical Argument by Properties

• Analogical Argument by Properties has the
  following form
• x has A, B, C. analogue case
• y has A, B. subject case
• It is probable therefore that y has C target
  feature

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Analogical Argument by Properties

• E.g.,
• Canada geese are water birds that nest in Canada
  in the early spring and migrate south to warmer
  climates for the winter months. Ducks are also
  water birds that nest in Canada in early spring.
  Therefore, ducks probably migrate south for the
  winter, too.

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Analogical Argument by Properties

• P1 analogue case Canada geese are water birds
  that nest in Canada in the early spring and
  migrate south to warmer climates for the winter
  months.
• P2 subject case Ducks are also water birds
  that nest in Canada in early spring.
• Conclusion Therefore, ducks probably migrate
  south for the winter target feature, too.

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Analogical Argument by Relations

• Analogical Argument by Relations has the
  following form
• x is to y analogue case as a is to b subject
  case.
• x is R to y.
• It is probable therefore that a is R to b target
  feature

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Analogical Argument by Relations

• E.g.,
• The proposal to give clean needles to prison
  inmates to stop the spread of AIDS from the use
  of dirty needles is ridiculous. It is like
  giving bank robbers normal bullets to stop them
  from using dum-dum bullets, which are much more
  damaging to the victim.

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Analogical Argument by Relations

• P1 Dum-dum bullets are to normal bullets (as
  used by bank robbers) analogue case as dirty
  needles are to clean (as used by prison inmates)
  subject case.
• P2 Although dum-dum bullets are much more
  damaging to the victim, normal bullets still kill
  their victims. Further, the role of police
  officers is to stop bank robbers, not prevent the
  harms they cause.
• Conclusion Although dirty needles are more
  damaging to the victim (addicts are likely to get
  HIV, etc.), clean needles can be just as damaging
  (e.g., overdoses). Further, the role of prison
  officials is to stop drug use, not prevent the
  harms caused by it.

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Analogical Reasoning

• When assessing these arguments, ask
• Are the analogue case and the target case
  relevantly similar?
• The more similar the two cases are, the stronger
  the analogy.
• Of course, everything is similar to everything
  else in some respect. You are looking for strong
  similarities.

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Chapter 14

• Irrational Techniques of Persuasion

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Irrational Techniques of Persuasion

• There are several techniques employed that may be
  persuasive in getting someone to accept the
  conclusion of an argument, but are often
  irrationally employed.
• They are irrational because one accepts the
  conclusion not because of reasons, but because of
  something else (e.g., emotion).

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Loaded Terms

• Loaded terms are terms which contain both a
  descriptive and evaluative meaning (we saw the
  difference between these types of uses of
  language in Ch. 2).
• Sometimes these words can be used to smuggle in
  an evaluation, when it appears, on the surface,
  that someone or something is being described.

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Loaded Terms

• E.g.
• terrorist
• freedom fighter
• Is Osama bib Laden a terrorist? Freedom fighter?
• Michael Collins? Che Guevara?

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Vague Terms

• Remember the distinction between ambiguity and
  vagueness (Ch. 2).
• Ambiguous terms are those that have two or more
  possible interpretations, and it is not clear
  which one is intended.
• Vague terms are those which are imprecise, but
  the intended meaning is clear.

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Vague Terms

• The use of ambiguous terms is always fallacious.
• The use of vague terms is only fallacious when
  precision is called for (sometimes it is not).
• In particular, the use of vague terms is
  fallacious when it is used to persuade you of
  something that is false.

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Vague Terms

• The use of vague terms is particularly evident in
  advertising.
• In particular, this is evident in the use of
  metaphorical words or phrases.

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Vague Terms

• E.g.,
• Coke is the Real Thing

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Loaded Questions

• Although arguments are composed of statements
  (sentences which are capable of being true or
  false), questions are sometimes used when arguing
  with another person.
• The answers to these questions (which themselves
  are statements) can then be used as premises.

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Loaded Questions

• There are certain questions that one ought to be
  aware of complex questions.
• A complex question contains an assumption that
  any answer to the question will confirm.
• The classic example is
• Have you stopped beating your wife?

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Loaded Questions

• No matter how you answer a complex question, you
  tacitly concede the assumption. (i.e., youre
  damned if you do, damned if you dont)
• In order to respond to complex questions, you can
  either
• Refuse to answer the question
• Ask that the question be rephrased without the
  assumption

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Loaded Questions

• Accusations can also be turned into questions.
• Instead of accusing someone of, e.g., of
  plagiarizing, you can ask Did you plagiarize?
• These accusative questions are particularly
  effective when the question is asked publicly.

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False Confidence

• Presenting a claim with confidence is a way in
  which someone may be convinced of the truth of
  that claim even if the evidence (or premises) do
  not support it with the same amount of
  confidence.
• If a claim is presented confidently, then it may
  not be called into question by ones opponent.

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False Confidence

• False confidence differs from a lie in that the
  person putting forward the claim believes it.
  Liars dont believe what they say.
• A person who is falsely confident believes the
  claim, but is lying about the confidence one
  should have in the evidence that would reasonably
  lead one to believe that claim.

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False Confidence

• E.g.
• Mongolian peasants use a method of predicting the
  sex of unborn children that is accurate more than
  95 per cent of the time. On a night when there
  is a full moon, the father spits into a cup of
  the mothers urine and leaves it on the doorstep
  of their hut overnight. If the spit is still
  floating the next morning, the baby will be a boy.

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Selectivity

• Selectivity occurs when information that detracts
  from your conclusion is omitted from the
  argument.
• In these cases, no lies are told, as the failure
  to include evidence contrary to your view is not
  a lie. Nevertheless, deceit occurs here.

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Selectivity

• This sort of deceit can be used quite effectively
  with inductive arguments.
• Induction by confirmation can succumb to this
  fallacy quite easily.

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Red Herring

• To introduce a red herring is to attempt to shift
  criticism from our own argument to another topic
  that distracts from the original criticism.
• P. 293 (text)

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Guilt By Association

• This argument is an analogical argument.
• It suggests a similarity between the opponent
  (subject) and another group (analogue), and
  infers that because the analogue group has a
  particular feature, the subject must have that
  feature as well.
• This is regarded as an irrational method because
  there is usually almost no (relevant) similarity
  between the two cases.

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Guilt By Association

• E.g.,
• We should not forget that the politicians who
  gave us medicare in Canada borrowed the idea from
  the communists, who first introduced medicare in
  the 1920s.

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Self-Test No. 21