1、Chapter 8,How good is the evidence: intuition, personal experience, testimonials, and appeals to authority? by雷玲、孙杰,The Need For Evidence,We encounter many conclusions , reasons, or assumptions, but we dont know whether they are dependable. We need evidence to prove whether they are true or false. T
2、he greater the quality and quantity of evidence supporting a claim, the more we can depend on it, and the more we can call the claim a “fact”.,How to determine dependability?,These questions: What is your proof? Where is the evidence? Are you sure thats true? How do you know thats true? Why do you b
3、elieve that? Can you prove it?,Locating factual claims (P.105),We encounter factual claims as (a) descriptive conclusion, (b) reasons used to support either descriptive or prescriptive conclusion, or (c) descriptive assumption. Examples : Frequently use of headphones may cause hearing loss.recent cr
4、ime statistics report an increase in the number of gun related crimes over the last 10 years. The monetary costs of switching to hybrid cars and alternative energy sources are far less than the political benefits to decreasing dependency on fossil fuel.,Sources of evidenceintuitionpersonal experienc
5、etestimonials appeals to authoritiespersonal observationscase examplesresearch studies analogies,Intuition as evidence,When we use intuition to support a claim, we rely on “common sense”, or on “gut feelings”, or on hunches. A major problem with intuition is that it is private. We must be very wary
6、of claims backed up only by intuition.,Dangers of appealing to personal experience as evidence,“I cross the street all the time without looking, and I have never been hit by a car. Therefore I do not see the need to look both ways before crossing.” Personal experience often lead us to commit the has
7、ty generalization fallacy.,Exceptions:When an experienced pilot has an intuition that the plane doesnt feel right as it taxis for takeoff. Sometimes such “hunches” are not blind.,Pay attention to the following problems with testimonials:,selectivitypersonal interest Omitted informationthe human fact
8、or,Personal Testimonials as Evidence “ All my friends are saying about the new phone. I should buy same quality.” How helpful is such evidence? Usually, not so good until we find out much more about the experience, interests, values, and biases behind them.,Appeals to authority as evidence “ Accordi
9、ng to my doctor, recent studies have shown that eating a couple of teaspoons of sugar a day can help fight the common cold.”We encounter appeals to many forms of authority on a daily basis. And we have little choice but to rely on them because we have neither the time nor the knowledge to become ade
10、pt in more than a few dimensions of our very complicated lives.,Thus we need to ask the questions：Has the authority developed a reputation for frequently making dependable claims? Have we been able to rely on this authority in the past?,Summary: clues for evaluating the evidence Use the following qu
11、estions to help access the various kinds of evidence.Intuition Does the intuition have any other kind of evidence support?,Personal testimonyWhat biases or interests might be affecting the persons testimony? Does the person have any expertise to assist his or her judgment? How do the persons value a
12、ssumption might be helpful in assessing this persons testimony? Whose personal testimony might be helpful in assessing this persons testimony? What information has been left out in this personal testimony?,Authority,How much expertise or training does the authority have on this particular subject? Was the authority in a position to have especially good access to pertinent facts? Is there good reason to believe that the authority is relatively free of distorting influences?,Welcome the next group!,
