Post on 07-Apr-2018
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Generalization andArgument by Example
forms of inductive
reasoning
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argument from generalization
Generalizations are one of the most commonforms of reasoning.
Definition: Generalizing involves attempts to
identify general patterns, gauge what is typical oraverage, or formulate general rules
Generalizing is necessary, indispensable Imagine what life would be like if you couldnt form
generalizations--if all knowledge was particularizedand fragmented.
Generalizing is also fraught with risks Think how many false stereotypes people hold about
race, gender, age, etc. What if Jim Abbot had believed people who said you
couldnt pitch in the major leagues with only one arm?
What if Stephen Hawking presumed that a person in awheelchair couldnt be a leading theoretical physicist?
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Bondes are dumb?
Blondes are dumb?
Does the stereotype refer only to
natural blondes?D
oes thestereotype only to female, notmale blondes?
Reese Witherspoon attendedStanford and won an oscar.
Hillary Clinton, law degree fromYale
Lisa Kudrow, degree in biologyfrom Vassar
Sharon Stone has a reported IQof 154
Kim Campbell, Canadas firstfemale prime minister, is blonde.
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White men cant jump?
Does the stereotype onlyapply to basketball?
Andrey Silnov, a Russian, won
the gold medal in the high jumpin Beijing in 2008.
Javier Sotomayor, a Cuban hasthe current world record in themens high jump.
Patrick Sjberg of Sweden hasthe 2nd highest world record inthe high jump
IgorPaklin, a Russian, has the3rd place world record,
Rudolph Povarnitsyn, anotherRussian, is 4th best. Andrey Silnov
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Asians are bad drivers?
AfricanorBlack
AngloorWhite
AsianandPacific
Islander
Hispanic orLatino
NativeAmerican
Percentage ofdeathsfromtraffic
fatalities
1.8 1.6 2.5 4.7 6.8
Does the stereotype apply to allAsians, or only some?
Are Taiwanese better than
Japanese or Vietnamese orKorean drivers? Does it apply to2nd or 3rd generation Asian-
Americans?
A study by the NHTSA publishedin 2006 revealed that Asiandrivers were not responsible for adisproportionate share of fatal
accidents As a percentage of the population
Hispanics and Native Americansaccounted for more fatal crashes.
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An Indian kid always wins thespelling bee?
An Indian kid (sub-Asian continent)always wins the national spelling bee?
4 of the past 9 winners were ofIndiandescent
National Spelling Bee Winners Since2000
2008 Sameer Mishra
2007 Evan ODorney
2006 Katharine Kerry Close 2005 Anurag Kashyap
2004 David Scott Pilarski Tidmarsh
2003 Sai R. Gunturi
2002 Pratyush Buddiga
2001 Sean Conley
2000 George Abraham Thampy
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Polling and surveys as a form ofgeneralizing
Public opinion polls
Nielsen ratings forTV shows
American Idol voting ratemyprofessor.com
call-screening on radio talk shows
To be truly valid a sample should be:
random
representative
sufficient in size.
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universal and statisticalgeneralizations
Universal generalization:Universal generalization: claims that all members of a group have certainattributes or characteristics
Asians are good at math.Feminists hate men.
Republicans favor tax cuts, Democrats oppose tax cuts.
Statistical generalization:Statistical generalization: claims that a percentage or a portion of a group hasa certain attribute or property.
76% of felons are recidivists
1 out of 3 children in the U.S. is born out of wedlock
19 of the 21 hijackers on Sept. 11 were Saudi Arabians. Contingent generalization: based on conditions or qualifications that must be
met for the generalization to hold true.Generalizations are more likely tohold true if they are confined to specific times, places, or situations
Most serial killers are male
The majority of journalists are Democrats
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inductive and deductivegeneralizations
Two types of generalizations: inductive and deductive
Inductive GeneralizationInductive Generalization:: bases a larger inference on an
example, sample, or particular instance
example: Babbs bought a Saturn and it runs well. Biff
bought a Saturn and it runs well. I guess Saturns are
reliable cars. (the generalization is based on a
nonrandom sample of 3 cars)
example: Of the 19 hijackers on Sept. 11, 15 wereSaudis. I think we can safely conclude that Saudi
Arabia is a breeding ground for terrorists.
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inductive and deductivegeneralizations
Deductive GeneralizationDeductive Generalization:: proceeds from a
general rule or general principle to a specific case
example: Brazilians love soccer. Hector is from
Brazil, so he probably loves soccer too.
example: Dont give money to that vagrant.
They are all winos and drug addicts.
example: Biff is a Republican, so of course hell
be opposed to gun control.
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tests of generalizations
How valid or reliable is the general rule?
Is the sample from which the generalization is
drawn random, and representative?
Is the sample from which the generalization is
drawn sufficient? (sample size)
Are there any exceptions to the rule?
Even if the general rule is true, does it apply in
this particular case?
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Reasoning by Example
A sub-set of inductive generalizations (a sample of one,
or a few)
Offers a generalization based on one or more cases to
other cases which are presumed to share the same
features as the example.
Examples may be based on personal experience,
hearsay, anecdotes, or case studies
example: testimonials on infomercials, The X47 Super mop
worked so well I threw away all my other mops!
example: deciding whether to take a class, see a movie, or
eat at a particular restaurant based on a friends say so.
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reasoning by example: Beware oftestimonials!
Thesetestimonials
serve as
examples of
how effective
diets,supplements, or
exercise
equipment is
He is a real person, but
was he selected at
random?
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Reasoning by example: Beware oftestimonials!
Before andAfter pictures
for miracle
diets, or
testimonials for
various productsare based on
examples.
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tests of examples
Is the example relevant or germane?
How typical or representative is the example?
Watch out for hand-picked examples
Do the examples cover a critical period of time?
Are there enough examples to prove the case?
Are there any negative or contradictory examples?