Some proponents of Global Warming have suggested that hurricanes are getting more intense due to Global Warming. Using the Hurricane data from the previous worksheets, support or refute this claim. E

Eight Week Session Module 5

How Good is the Evidence: Intuition, appeals to Authority and Testimonial?

FACTUAL CLAIMS

Factual claims are beliefs about the way the world is, was, or is going to be that the communicator wants you to accept as “fact”.

The first question you should ask when encountering a factual claim is, “Why should I believe it?” Your next question should be, “Does the claim need evidence to support it?” If the factual claim requires evidence and none is provided it is considered an assertion, not a factual claim.

If the factual claim requires evidence, and that evidence has been provided, then you must ask, “How good is the evidence?” When dealing with evidence the one thing to keep in mind is that there are no absolutes. You should be concerned with the “dependability” of the evidence, not the absolute correctness of it.

SOURCES OF FACTUAL CLAIMS

Descriptive Conclusions

Reasons

Descriptive Assumptions

ACCEPTABLE FACTUAL CLAIMS

There are three instances when you can readily accept a factual claim as fact.

Undisputed Common Knowledge

Claim is Based on a Well-Reasoned Argument

Claim is Supported By Solid Evidence

MAJOR KINDS OF EVIDENCE

Intuition

Testimonials

Appeals to Authority

Personal Experience

Personal Observation

Case Studies and Examples

Research Studies

Analogies

INTUITION

Intuition can be a hunch, a “gut feeling”, or just common sense based on experience. One person’s common sense may not be the same as another person’s common sense, so whom should we believe? Well the problem with intuition is that it is based on your personal experiences or lack thereof; consequently, we must be skeptical of claims based on intuition because your experiences most likely do not represent all experiences. Limitations in our experience create a false sense of knowledge, one that most of us are not willing to admit. Thus, intuition is not a very good form of evidence.

Imagine if all your experience with a particular race came from viewing TV and it was negative. Upon first meeting someone of this race, would your intuition tell you to be cautious or wary of this person or would you be able to set aside all your negative impressions and treat this person impartially?

PERSONAL TESTIMONIALS

Personal testimonials are one of the most biased forms of evidence. They are based on selective experiences and often are provided by individuals having a personal interest or conflict of interest in the outcome. You may be aware of Doctor’s who have been paid by pharmaceutical companies to speak at conferences, promoting their drug. You may recall the Pfizer commercial on Lipitor in which the Doctor was providing personal testimony that proved to be false and he subsequently resigned.

APPEALS TO QUESTIONABLE AUTHORITY

Appeals to Authorities can include Medical Experts, Clergy, and College Professors to name a few. None of these groups are infallible and very often you will encounter a diverse range of opinions amongst them. We must remember that experts do not know everything about a certain topic, rather they know more about a certain topic than the rest of us.

If experts truly knew everything about a particular topic, then you would never have experts who disagree. However, experts disagree all the time. Another problem with invoking an authority is their experience. If you were charged with a crime and going to trial, would you hire a lawyer just out of law school, or would you rather engage an attorney with trial experience?

PERSONAL EXPERIENCE

We often turn to family and friends, and to their personal experiences, as a form of evidence. Your car’s engine sounds funny, or you have a toothache, and you are not sure what to do. The natural inclination is to ask someone for his or her experience.

Personal experience can be useful; however, it does have its flaws. The major problem with personal experience is that it tends to draw on generalizations, rather than on specific criteria.

Chapter 5 Huff

The Gee Whiz Graph

Graphs and charts are useful visual tools to convey statistical information. However, just like the numbers they represent, charts and graphs can be very misleading.

Graphs show comparisons or distributions, which may be represented in percentages or absolute values. There are several types of graphs: bar graphs, line graphs, circle, and scatter-plots or graphs.

Below, you will see the graphic representation of data, in which I have purposely omitted the title and labels. Without such labels, you may not be able to figure out what this graph is supposed to represent.

The vertical column represents frequency and consequently should be labeled indicating whether this is days, weeks, years, minutes, or hours.

The horizontal column, which is identified, is not labeled.

Now let’s see what this figure should look like. Properly labeled, we now have no difficulty determining the frequency (mean) for category 3-5 hurricanes for any particular decade.

What was the mean for the decade 1941-1950?

Source: National Hurricanes Center 2004 - Category 3-5 Hurricanes per decade.

Let’s look at these data represented as a line graph. Line graphs can also be used to show comparisons in experiments or display distributions.

Source: National Hurricane Center 2004

Scatter Plots- a special form of a line graph.

In research experiments, the independent variable x (cause) is plotted on the horizontal axis and the dependent variable y (effect) is plotted on the vertical axis. Scatter plots used in correlations sometimes refer to the independent variable as the predictor or explanatory variable and the dependent variable is called the response variable because in correlation we are looking at the mathematical relationship between two variables, not the cause and effect relationship, which cannot be determined from correlation.

Scatter plots consists of single dots that are plotted as if on a line graph, but the dots are not joined. The dots represent where the variables intersect.

Source: NetMBA.com (Business Knowledge Center 2011)

Now that you know what a graph should look like, it should help you in identifying deceptive graphs.

Manipulating the vertical axis can alter your graph, creating a false impression. Nothing has changed in terms of values, but chart C provides a more impressive visual impact than do charts A or B.

CHART A

CHART B

CHART C

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