Evaluating fact 5 pptx

But you need to have the following: ■ The effect must occur after the cause.. By focusing on parts of a whole and drawing a conclusion based only on those parts, you create a composition

On the other hand, what if you have been

study-ing and gettstudy-ing good grades and there is a test comstudy-ing

up? You are busy with other things and don’t study for

it You get a D on the test The argument goes like this:

Every time I have a test coming up, I study

for it and get good grades This time, I

didn’t study, and I got a D

If you don’t want to get more Ds in the future, you

will want to know what caused the bad grade,

pre-venting the unwanted result by prepre-venting the cause

What is the key difference in the argument? Studying

In this case, the key difference means if you don’t want

bad grades, you must study Remember that in order to

determine cause, an argument must be formed that

looks for a key difference between two otherwise

sim-ilar events

Here is another example:

You had a stomachache on Thursday and

you are trying to figure out why Every

morning for breakfast you eat bran cereal

with skim milk and a banana But,

Thurs-day you were out of milk and had toast

for breakfast instead By midmorning, you

had a painful stomachache You picked up

milk on the way home from work and had

your usual breakfast on Friday The

stom-achache did not occur on Friday Nothing

else in your routine was out of the

ordinary

What caused the stomachache? Chances are, it

was the toast you ate for breakfast It is the key

differ-not this easy, however Sometimes the key difference is difficult to spot and requires an inference based on the information presented in the argument

Real-life situations can get complicated Our lives and the world around us are affected by thousands of details, making the finding of one key difference diffi-cult That said, if there is a strong likelihood of causa-tion and there are no other obvious causes, you can make a convincing causal argument But you need to have the following:

■ The effect must occur after the cause This

sounds like common sense, but there are many arguments that place the effect before the cause

Example

You are blamed for a computer problem at work However, you did not use the computer until after the problem was detected The argu-ment against you has no strength

■ You need more than just a strong correlation

to prove causation Coincidence can often

explain what might first appear to be cause and effect

Example

Every time you wear your blue sweater, your team wins the game Can you determine that if you always wear the sweater, your team will always win? The answer is no, because there is

no causation Nothing about your wearing the sweater could have caused a certain outcome in

a game

Practice

Look for causation in the following scenario

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wheel and move forward, when another

car backed out of a spot behind me She

drove right into me, smashing my left rear

door with the corner of her bumper The

other driver told the police officer that I

hit her But he agreed with me that it was

her fault, and wrote down why on the

police report

What did the police officer write? Circle all that

could apply

a Drivers must wait their turn if another car is

already pulling out of a parking space behind

them It is clear that the first car was already out

of her space when she was hit on her door

b It is impossible to hit the corner of someone’s

bumper with your rear door when backing out of

a parking spot It is possible to hit the rear door

of someone’s car with the corner of your bumper

c Speeding in parking lots is prohibited by law.

d The other driver must not have been looking in

her rearview mirror, or she would not have backed into the other car

Answer The probable causes of the car accident are a, b, and d.

While speeding in parking lots is never a good idea, it was not a factor in this accident

 I n S h o r t

Inductive reasoning uses specific information that has been observed or experienced, and draws general con-clusions about it To make those concon-clusions, it relies

on either (or both) past experience and common sense Because the conclusions can only state what is likely or probable, there is a greater chance of error with induc-tive reasoning as opposed to deducinduc-tive reasoning In the next lesson, you will learn about specific ways in which inductive reasoning goes wrong

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You are always drawing conclusions from your observations Pay attention to this inductive reason-ing and evaluate your skills Are you usreason-ing common sense and/or past experience? Have you noticed

a key difference, or compared two similar events? Become a better user of inductive reasoning by being aware of when and how you use it

Skill Building Until Next Time

A N I N D U C T I V E C O N C LU S I O N is only as good as the quantity and quality of its premises.

There are a number of ways in which to create a strong inductive argument, and just as many ways to create a weak one The premises must contain enough evidence or the conclusion

will be what is known as a hasty generalization If you claim cause and effect and there is not enough evi-dence, you create a chicken and egg fallacy If the conclusion you draw does not fit the facts, it is a fallacy

known as post hoc, ergo propter hoc By focusing on parts of a whole and drawing a conclusion based only

on those parts, you create a composition fallacy.

It is important to understand how these fallacies work so you can avoid them in your own arguments and recognize them when they are used by others

L E S S O N

Misusing Inductive Reasoning—

Logical Fallacies

L E S S O N S U M M A R Y

An inductive fallacy looks like an argument, but it either has two prem-ises that do not provide enough support for the conclusion, or a con-clusion that does not fit the premises This lesson helps you spot them

so you are not taken in by their faulty logic

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 C h i c k e n a n d E g g ( C o n f u s i n g

C a u s e a n d E f f e c t )

The age-old question,“which came first, the chicken or

the egg?” is used to describe dilemmas to which there

are no easy answers In terms of logical arguments,

when you are not sure which came first, you could

make an error by confusing cause and effect Just

because two things regularly occur together, you

can-not necessarily determine that one causes the other

Chicken and egg is a fallacy that has the following

gen-eral form:

1 A and B regularly occur together.

2 Therefore, A is the cause of B.

This fallacy requires that there is no common

cause that actually causes both A and B, and that an

assumption is made that one event must cause another

just because the events occur together The assumption

is based on inadequate justification; there is not enough

evidence to draw the causal conclusion

A common example of the chicken and egg

fal-lacy is the relationship between television and movie

violence and real-life violent behavior Many people

believe that violent behavior is the result of watching

TV and movie violence Many others believe that

peo-ple are violent, and therefore they create, watch, and

enjoy violent programming Does television violence

cause real-life violence, or vice versa? Or, is there no

causal relationship between the two? The simple fact

that some people are violent, and some entertaining TV

shows and movies contain violence, is not enough to

assert a connection

tion to the sequence of events If A happens after B, A can’t cause B Another way is to ask yourself if there is anything else that could have been the cause Think about the evidence presented Is it enough to draw the conclusion?

Examples

■ Many people who have lung cancer are smok-ers Having lung cancer causes people to smoke

■ If you keep speeding, you will become a bad driver

■ Last night I had a fever This morning, I have a cold and a fever The fever caused the cold

Practice

Which of the following is NOT a chicken and egg fallacy?

a Johnny Cash was famous He was also on

televi-sion frequently Johnny Cash was famous because

he was on television frequently

b I didn’t wash dishes all week My dirty dishes

started to grow mold If I don’t want mold grow-ing on my dishes, I should wash them

c My boss really liked the work I did on my latest

project I didn’t work as hard on the project as I usually do In order to make my boss happy, I shouldn’t work as hard as I usually do

d Your grades went down this semester You joined

a study group this semester Your grades went down because you joined the study group

Answer Choice b is not a chicken and egg fallacy, it is a logical inductive argument Choices a, c, and d are all

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both A and B, or a reversal (B caused A, and not the

other way around)

 J u m p i n g t o C o n c l u s i o n s

( H a s t y G e n e r a l i z a t i o n )

In this fallacy, there are too few samples to prove a

point While you can’t be expected to poll thousands of

people or know the outcome of every instance of a

par-ticular event, your sample must be large enough to

draw a conclusion from For example, a waitress

com-plains,“those Southerners left me a lousy tip All

South-erners are cheap!” She has made a generalization about

tens of millions of people based on an experience with

a few of them

A hasty generalization takes the following form:

1 A very small sample A is taken from

popula-tion B

2 Generalization C is made about population B

based on sample A

There are two common reasons for hasty

gener-alizations One is because of bias or prejudice For

instance, a sexist person could conclude that all

women are bad drivers because he had an accident with

one (See Lesson 8 for more information about bias and

prejudice in arguments.) Hasty generalizations are also

often made because of negligence or laziness It is not

always easy to get a large enough sample to draw a

rea-sonable conclusion But if you can’t get the right

sam-ple, do not make the generalization Better yet, make an

attempt to add to your sample size Improve your

argument with better evidence

How do you know when your sample is large

enough? There is no one rule that applies to every type

of sample, so you will need to use the “practicality and

reasonability” test What is the largest sample you can gather that makes sense, practically? Will it be large enough so that you can reasonably make a generaliza-tion about it? Reread the secgeneraliza-tion on statistics in Lesson

10 to refresh your memory about the problems that can occur when taking a sample, and how those problems can be recognized and/or avoided

Make an effort to avoid jumping to conclusions, and learn to spot such conclusions in the arguments of others by being certain that bias is not playing a role

If the generalization is the result of preexisting opin-ions about the population in question, the bias needs

to be removed and the generalization rethought, based

on real information For example, you do not want to draw a conclusion about a particular type of person if all you have to rely on are a couple of isolated, nega-tive past experiences

Second, take the time to form an adequate sam-ple Your sample must be large enough that it makes sense to draw a conclusion from it For instance, if you are drawing a conclusion about a large group of peo-ple, you will need to find out about many more of them than you would if you were drawing a conclusion about

a very small group

Examples

■ I asked eight of my coworkers what they thought of the new manufacturing rules, and they all thought they are a bad idea The new rules are generally unpopular

■ That new police drama is a really well done show All police dramas are great shows

■ Omar threw the ball from left field to the sec-ond baseman, and he made an incredible dou-ble play Whenever Omar gets the ball, he should throw it to the second baseman

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