1.Non-Causal Relationship
2.The Fallacy of Analogy and Comparison
3.Concerning Data, Statistics or Appeal to Authority
4.Sufficient Evidence and Necessary Condition
5.Composition and Division
6.Assuming all things unchanged.
7.False Dilemma
8.Ad Hominem, Straw Argument
1.Non-Causal Relationship
a, Correlation Mistaken for Causation
- The following appeared in the editorial section of a local newspaper.
Commuter use of the new subway train is exceeding the transit company's projections. However, commuter use of the shuttle buses that transport people to the subway stations is below the projected volume. If the transit company expects commuters to ride the shuttle buses to the subway rather than drive there, it must either reduce the shuttle bus fares or increase the price of parking at the subway stations.
The argument depends on an unproven cause-and-effect relationship between the unexpectedly low shuttle bus usage and shuttle-bus fares and station-parking fees. The reason
for the unexpectedly low shuttle-bus usage might have nothing to so with either shuttle-bus fares
or station-parking fees. For instance, commuter's awareness of the shuttle-bus option might be
growing more slowly than anticipated. for that matter, many commuters might be wary of
riding the buses due to a recent shuttle-bus accident. Without ruling out these and other
alternative explanations for the low shuttle-bus usage, the author cannot reasonably conclude
that adjusting shuttle fares or station-parking fees will have any effect on that usage.
b. The " After This, Therefore Because of This " Fallacy.
- The following appeared in the editorial section of a local newspaper.
In the first four years that Montoya has served as mayor of the city of San Perdito, the population had decreased and the unemployment rate has increased. Two business have closed for each new business that has opened. Under Varro, who served for four years before Montoya, the unemployment rate decreased and the population increased. Clearly, the residents of San Perditto would be best served if they voted out of office and reelected Varro.
The author assumes that the Montoya administration caused the unemployment in San Perdito
as well as its population loss. The line of reasoning is that because Montaya was elected
before the rise in in unemployment and the decline in population, the former event caused the
latter. But this is fallacious reasoning unless other possible casual explanations have been
considered and ruled out. For example, perhaps a statewide or nationwide recession is the
cause if these events. Or perhaps the current economic downturn is part of a larger pattern of
economic cycles and trends, and has nothing to do with who happens to be the mayor. Yet
another possibility is that Verro enjoyed a period of economic stability and Verro's own administration set the stage for the unemployment and declining in population the city is now
experiencing under Montoya.
c. Confuse the Cause and Effect
- Two years ago, the town of Ocean View built a new municipal golf course and resort hotel. During the past two years, tourism in Ocean View has increased, new businesses have opened there, and Ocean View's tax revenues have risen by 30 percent. Therefore, the best way to improve Hopewell's economy. and generate additional tax revenues, is to build a golf course and resort hotel similar to those in Ocean View.
This argument used the " Analogy as Reasoning ". It is possible that the mayor has confused
cause with effect respecting the recent development in Ocean View. Perhaps Ocean View's
construction of a new golf course and hotel was response to previous increases in tourism and
business development - increases that have simply continued during the most recent two years.
Since the mayor had failed to account for this possibility, the claim that Hopewell would boost
its economy by also constructing a golf course and hotel is completely unwarranted.
The mayor failed to account for other possible account for other possible causes of the trends
in Ocean View during the last two years. The increase in tourism might have been due to improving economic conditions nationwide, or to unusually pleasant weather in the region. The
new businesses that have opened in Ocean View might have opened there irrespective of the
new golf course and hotel. And the 30% increase tax revenues might have been the result of
an increase in tax rates, or the addition of a new type of municipal tax. Without ruling out these
and other alternative explanations for the three recent trends in Ocean View, the mayor cannot
reasonably infer based on those trends that Hopewell's economy would benefit by following
Ocean View's example.
d.Casual Oversimplification
- For the third year in a row, the average household income in our country has risen significantly. That prosperity means that families are likely to be spending more time and money on leisure activities. Megamart stores should therefore concentrate on enlarging and promoting its line of products typically used in leisure activities : athletic and outdoor equipment, televisions, gourmet cooking equipment, and luggage and travel accessories.
a. The fallacy of analogy
- Over time, the costs of processing go down because as organizations learn how to do things better, they become more efficient. in color film processing, for example, the cost of a 3-by-5-inch print fell from 50 cents for five-day service in 1970 to 20 cents for one-day service in 1984. The same principle applies to the processing of food. And since Olympic Foods will soon celebrate its twenty-fifth birthday, we can expect that our long experience will enable us to minimize costs and thus maximizes profits.
It is highly doubtful that the facts drawn from the color-film processing industry are applicable
to the food processing industry. Differences between the two industries clearly outweigh
the similarities, making the analogy invalid. For example, problems of spoilage, contamination,
and timely transportation all affect the food industry but are virtually absent in the film-processing industry. Problems such as these might present insurmountable obstacles
that prevent lowering food-processing costs in the future.
b. Incomplete or Selective Comparison
- Professor Taylor of Jones University is promoting a model of foreign language instruction in which students receive ten weeks of intensive training, then go abroad to live with families for ten weeks. The superiority of the model, Professor Taylor contends is proved by the results of a study in which foreign language tests given to students at 25 other colleges show that first-year at Jones speak more fluently after only ten to twenty weeks in the program than do nine out of ten foreign language majors elsewhere at the time of their graduation.
The argument is based on the assumption that students from Professor Taylor's program have
learned more than foreign language students at other universities. However, we are not given
enough information about the study to be sure that this comparison is reliable. For example, the
article does not tell us whether the foreign language students at Jones were given the tests; it
only reports that the tests in question were "given to students at 25other colleges." If Jones
students were not tested, then no basis exist for comparing then to students at other universities. In addition, the article does not indicate whether students at all the universities,
including Jones, were given the same tests. If not, no basis exists for the comparisons.
3. Concerning data
a. The insufficient Sample Fallacy
- The following appeared as part of an article in a health club trade publication.
After experiencing a decline in usage by its members, Healthy Heart fitness center built an indoor pool. Since usage did not increase significantly, it appeared that health club managers should adopt another approach-lowering membership fees rather installing expensive new features.
The conclusion that installing new features at fitness centers will not increase member usage
is based on too small a sample to be reliable. The only evidence offered in support of this
conclusion is the fact that Healthy Heart fitness center did not experience an increase. Unless,
it can be shown that Healthy Heart us typical of all fitness centers, the fact that it experienced
no increase in member usage is not grounds for concluding that all fitness centers will
experience similar results.
- The following appeared in a newspaper story giving advice about investment.
As overall life expectancy continues to rise, the population of our country is growing increasingly older. For example, over twenty percent of the residents of one of our more populated regions are now at least 65 years old, and occupancy rates at resort hotels in that region declined significantly during the past six months. Because of these two related trends, a prudent investor would be well advised to sell interest in hotels and invest in hospitals and nursing homes instead.
The author provides no evidence to support the claim that the population as a whole is aging
and that the hotel occupancy in general is declining. The example cited, while suggestive of
these trends, is insufficient to warrant their truth because there is no reason to believe that
data drawn from this unmanned region is representative of the entire country. For example,
if the region from which the data was gathered was Florida, it would clearly be unrepresentative. The reason for this is obvious. Florida is populated by a disproportionate
number of retired people over 65 years old and is a very popular vacation destination during
the winter months. Moreover, resort hotel occupancy in Florida typically declines signifcantly
during the summer months.
b. The Biased Sample Fallacy
- Among Newtrue employees participating in our department's most recent survey, about half indicated that they are happy with our current four-day work week. These survey results show that the most effective way to improve overall productivity at Newtrue is to allow each employee to choose for himself either a four-day or five-day work week.
The survey methodology might be problematic in two respects. First, we are not informed
whether the survey required that respondents choose their work-week preference between
alternatives. If it did, then the results might distort the preferences of the respondents, who might very well prefer a work-schedule choice not provided for in the survey. Secondly, we are not informed whether survey responses were anonymous or even confidential. If they were not,
then respondents might have provided responses that they believed their superiors would
approve of, regardless of whether the response were truthful. In either event, the survey results
would be unreliable for the purpose of drawing any conclusions about Newtrue employees
preferences, let alone about how to improve overall productivity at Newtrue.
- Who conducted the survey ?
- Are the statistics misleadingly vague ?
- When was the survey conducted ?
- Managers at our central office report that their employees tend to be most productive in the days immediately preceding a vacation. To help counteract our declining market share, we could increase the productivity of our professional staff members, who currently receive four weeks paid vacation a year, by limiting them to a maximum of one week's continuous vacation time. They will thus take more vacation breaks during a year and give us more days of maximum productivity.
Comment :
The memo provides no evidence that reports from the managers are reliable. The managers
all have vested interests in the vacation policies, and therefore might fabricated the reports so
that the company would adopt policies that they would prefer for themselves. The memo's
author must first convince me that the reports are not biased. Not until then could I begin to
consider the department's recommendation.
- The following appeared in a memorandum from the Director of Human Resources to the executive officers of Company X.
Last year, we surveyed our employees on improvements needed at Company X by having them rank, in order of importance, the issues presented a list of possible improvements. Improved communications between employees and management was consistently ranked as the issue of highest importance by the employees who responded to the survey. As you know, we have since instituted regular communications sessions (conducted by high-level management,) which the employees can attend on a voluntary basis. Therefore, it is likely that most employees at Company X now feel that the improvement most needed at the company has been made.
Even if the survey accurately ranks certain issues according to level of employee concern,
the highest ranked issue in the survey might not be the issue about which employees are most
concerned. Why ? The improvement most needed from the point of view of the employees might not have appeared as one of the choices on the survey. for example, if the list of improvement presented on the survey was created by management rather than by the
employees, the the issue of greatest concern to the employees might not be included on the
list. Lacking information about how the survey was prepared, it is impossible to assess its reliability. Consequently, any conclusion based on it is highly questionable.
(2) Are the statistics misleading vague ?
- Re-elect Adams, an you will be voting for proven leadership in improving the state's economy. Over the past year along, seventy percent of the state's workers have had increases in their wages, five thousand new jobs have been created, and six corporations have located their headquarters here. Most of respondents in a recent poll said they believed that the economy is likely to continue improve if Adams is reelected. Adams's opponent, Zebulon, would lead our state in the wrong direction, because Zebulon disagrees with many of Adams;s economic policies.
First, the statistics are intended to support the main claim that the state is economically better
off with Adams as governor. But these statistics are vague and oversimplified, and thus may
distort the state's overall economic picture. For example, state workers' pay raise may have
been minuscule and may not have kept up with cost of living or with pay for state workers in
other states. Moreover, the 5,000 new jobs may have been too few to bring state unemployment
rates down significantly; at the same time, many jobs may have been lost. Finally, the poll
indicates that six new corporations relocated to the state, but fails to indicate if any left.
Next, the poll cited by the author is described in the vaguest possible terms. The as does not
indicate who conclude the poll, who responded, or how the poll was conducted. Until these
questions are answered, the survey results are worthless as evidence for public opinion about
Adams or his economic policies.
Finally, while we have only vague and possibly distorted evidence that the state is better off with
Adams, we have absolutely no evidence that it would be worse off with Zebulon. Given that the
state economy is good as the moment, none of the author's reasons reasons establishes that
Adams is the cause of this. And neither do they establish that the state wouldn't be even better
off with someone else in office.
(3) When was the survey conducted ?
- The practice of officially changing speed limits on the highways-whether by increasing or decreasing them - is a dangerous one. Consider what happened over the past decade whenever neighboring East Cambria changed its speed limits : an average of 3 percent more automobile accidents occurred during the week following the change than had occurred during the week preceding it - even the speed limit was lowered. This statistic shows that the change in speed limit adversely affected the alertness of drivers.
It is unlikely that brief one-week periods under comparison are representative of longer time
periods. A difference of only 3 percent during one particular week can easily be accounted
for by other factors, such as heavy holiday traffic or bad weather, or by problems with reporting
or sampling. Had the editorial indicated that several speed-limit changes in East Cambria
contributed to the statistic, the argument would be more convincing; but for all we know, the
statistic is based on only one such change. In any event, a one-week period is too brief be
representative because it is likely that accidents will occur more frequently immediately
following the change, while people adjust to the new limit, than over the longer therm when drivers have become accustomed to the change.
4.Sufficient Evidence and Necessary Condition
Unless ABC Company hires the former marketing director of XYZ Company, ABC will not
reverse its current profit decline. By hiring the former marketing director of XYZ Company, ABC Company will boost its profits. In order to boost its profits, ABC Company should hire the former marketing director of XYZ Company.
a.Sufficient - condition Problems
- It makes no sense that in most places fifteen-year-olds are not eligible for their driver's license while people who are far older can retain all of their driving privileges by simply renewing their license. If older drivers can get these renewals, often without having to pass another driving test, then fifteen-year-older should be eligible to get a license. Fifteen-year-olds typically have much better eyesight, especially at night; much better hand-eye coordination; and much quicker reflexes. They are also less likely to feel confused by unexpected developments or disoriented in unfamiliar surroundings, and they recover from injuries more quickly.
Even if it is granted that fifteen-year-olds possess better high vision, reflexes, hand-eye
coordination, and are less disorientated in unfamiliar surroundings than older drivers, these
abilities do not qualify them to obtain a driver's license. The author assumes that physical
capabilities are the only attributes necessary to operate a motor vehicle. But this assumption
is clearly mistaken. In addition to these abilities, drivers must be able to exercise good
judgment in all types of driving situations and conditions and must be cognizant of the
consequences of their decisions and actions when driving. It is because fifteen-year-olds
typically lack these latter abilities that they are denied driving privileges.
b. Necessary-condition Problems
- Scientists must typically work 60 to 80 hours a week if they hope to further their careers; consequently, good and affordable all-day child care must be made available to both male and female scientists if they are to advance in their fields. Moreover, requirements for career advancement must be made more flexible so that preschool-age children can speed a significant portion of each day with a parent.
In this argument, the author asserts that in order for scientists, male and female alike, to
further their career, they must access to good, affordable, all-day child care. However, the
author fails to consider and rule out other options for ensuring proper care for scientists'
children during the workday. For instance, a scientist whose spouse (or partner) has time
during each day to spend with their child requires no professional day care. Besides, many
scientists-parents, including scientists single-parent scientists, might have friends or relatives
who can provide child care. Furthermore, childless scientists or scientists whose children are
old enough to take care of themselves will have no need for the services advocated in the
argument. Thus, to the extent that scientists have other options to ensure day care for their
children, the author's assertion that scientists must have access to good, affordable, all-day
child care is unwarranted.
c. Sufficient and Necessary Condition Problems
- Application for advertising spots on KMTV, our local cable television channel, decreased lat year. Meanwhile a neighboring town's local channel, KOOP, changed its focus to farming issues and reported an increase in advertising applications for the year. To increase applications for advertising spots, KMTV should focus its programming on farming issues as well.
The argument depends on the assumption that the proposed change is the only way KMTV
can stimulate advertising applications. Common sense tells me that there are other ways of
doing this - reducing advertising rates, improving programming quality, or extending broadcast
range, to list just a few. The author must explain either why none of these options are available
or why they would fail to stimulate applications. Otherwise, I cannot accept that the proposed
change is necessary.In addition, the author further assumes that the proposed programming
change would suffer to bring about the desired increase. However, if it turns out that last year's
decline was due to a combination of factors, some of which will remain unchanged in the future,
a mere programming shift might not have a stimulating impact on application.
5. Composition and Division
a. What is true for a group is also true for any member
- It is no longer coat-effective for the Perks Company to continue offering its employees a generous package of benefits and incentives year after year. In periods when national unemployment rate are low, Perks may need offer such a package in order to attract and keep good employees, but since national unemployment rate are now high, Perks does not need to offer the same benefits and incentives. The money thus saved could be better used to replace the exiting plant machinery with more technologically sophisticated equipment, or even to build an additional plant.
The author relies on the reasoning that it is unnecessary to pay relatively high wages during
periods of high unemployment because the market will supply good employees at lower rates
of pay. While the reasoning may be sound in a general sense, the particular industry that Perks
is involved in may not be representative of general unemployment levels. It is possible that
relatively few unemployed people have the type of qualifications that match job openings at
Perks. If this is the case, the claim that it it easier now to attract good employees at lower wages is ill-founded.
b. What is true for a member is also true for the group
- This is a common misconception that university hospitals are better than community or private hospitals. This notion is unfounded, however : the university hospitals in our region employ 15 percent fewer doctors, have 20 percent lower success rate in treating patients, make far less overall profit, and pay their medical staff considerably less than do private hospitals. Furthermore, many doctors at university hospitals typically divide their time among teaching, conducting research, and treating patients, From this it seems clear that the quality of care at university hospitals is lower than at other kinds of hospitals.
The most egregious reasoning error in the argument is the author's use of evidence pertaining
to university hospitals in this region as the basis for a generalization about all universities
hospitals. The underlying assumption operative in this inference is that university hospitals in
this region are representative of all university hospitals. No evidence is offered to support this
gratuitous assumption.
c. The Fallacy of Hasty Generalization
Most students in Riverside school must have participated in gang activities, because six
students from this school last year were involved in gang crimes.
6. Assuming all things remain unchanged over time
a. Past conditions remain unchanged in the present and future
- Mental health experts have observed that symptoms of mental illness are less pronounced in many patients after group music-therapy sessions, and job openings in the music-therapy filed have increased during the past year. Consequently, graduates from our degree program for music therapists should have no trouble finding good positions. To help improve the financial status of Omega University, we should therefore expand our music-therapy degree program by increasing its enrollment targets.
The argument depends on the assumption that in the future will continue to be sufficient job
openings in music therapy for Omega graduates. however, a recent one-year increase is
insufficient evidence in itself to convince me that this trend will continue, providing a ready job
supply for new Omega graduates. Moreover, should this trend actually reverse, then adopting
the chair's proposal might result in a decrease Omega's job placement rate, which might very
well have a negative impact on the school's overall reputation and, in turn, financial status.
b. Present conditions will remain unchanged into future
- The following appeared as part of the business plan of an investment and financial consulting firm. Studies suggest that an average coffee drinker's consumption of coffee increases with age, from age 10 through age 60. Even after age 60, coffee consumption remain high. The average cola drinker's consumption of cola, however, declines with increasing age. Both of these trends have remained stable for the past 40 years. Given that the number of older adults will significantly increase as the population ages over the next 20 years. it follows that the demand for coffee will increase and demand for cola will decrease during this period. We should, therefore, consider transferring our investment from Cola Loca to Early Bird Coffee.
The argument assumes that relative supply conditions will remain unchanged over the next twenty years. However, the supply and cost and coffee beans, as well as other costs of doing
business as a producer of coffee or cola, may fluctuate greatly greatly over a long time period.
Thees factors may affect comparative prices of coffee and cola, which in turn may affect
comparative demand and the value of investment in coffee and cola companies. Without
considering other factors that contribute to the value of a coffee or cola company, the firm
cannot justify its recommendation.
7. False Dilemma (The Either or Thinking, The Black-White Fallacy)
- The following appeared in the editorial section of a local newspaper. Commuter use of the new subway train is exceeding in the transit company's projections. However, commuter use of the shuttle buses that transport people to the subway station is below the projected volume. If the transit company expects commuters to ride the shuttle buses to the subway rather than drive there, it must either reduce the shuttle bus fares or increase the price of parking at the subway stations.
The author assumes that reducing shuttle fees and increasing parking fees are mutually
exclusive alternatives. However, the author provides no reason for imposing an either/or
choice. Adjusting both shuttle fares and parking fees might produce better results. Moreover,
if the author is wrong in the assumption that parking fees and shuttle fees are the only possible
cause of the problem, then the most effective solution might include a combination of policy
charges - for example, in shuttle fares, parking fees, rerouting , and rescheduling.
8. Other
a. Failing to weighing the advantage and disadvantage thoroughly.
- The following appeared in a memorandum from the business department of the Apogee Company. When the Apogee Company had all its operation in one location, it was more profitable than it is today. Therefore, the Apogee Company should close down its field offices and conduct all its operations from a single location. Such centralization would improve profitability by cutting costs and helping the company maintain better supervision of all employees.
The author assumes that centralization would improve profitability by cutting costs and
streamlining supervision of employees. This assumption is not supported with any data or
projections. Moreover, the assumption fails to take into account cost increases and inefficiency
that could result from centralization. For instance, company representatives would have to travel to do business in areas formerly served by a field coffee, creating travel costs and loss of
critical time. In short, this assumption must be supported with a thorough cost-benefit analysis
of centralization versus possible cost-cutting and/or profit-enhancing strategies.
b. Failing to define important terms
- The following appeared in a speech delivered by a member of the city council.
Twenty years ago, only half of the students who graduated from Einstein High School went on to attend a college or university. Today, two thirds of the students who graduate from Einstein do so. Clearly, Einstein has improved its educational effectiveness over the past two decades. This improvement has occurred despite the fact that the school's funding, when adjusted for inflation, is about the same as it was twenty years ago. Therefore, we do not need to make any substantial increase in the school's funding as this time.
We must establish the meaning of the vague concept " educational efficiency ". If the term is
synonymous with the rate of graduation to college, the the statistics cited would strongly
support the argument. But, typically we are interested in something more than just the numbers
of students who go on to college experience - that is, whether the school has provided a good
secondary education. Thus, for the speaker the term " educational efficiency " must essentially
carry the same meaning as " educational quality ."
c. Circular Reasoning (Tautology , Begging the Question)
- The following appeared in a letter from the owner of the Sunnyside Towers apartment building to its manager. One month ago, all the showerheads on the first five floors of Sunnyside Towers were modified to restrict the water flow to approximately 1/3 of its original force. Although actual readings of water usage before and after the adjustment are not yet available, the change will obviously result in a considerable savings for Sunnyside Corporation, since the corporation must pay for water each month. Except for a few complaints about how water pressure, no problems with showers have been reported since the adjustment. Clearly, restricting water flow throughout all the 20 floors of Sunnyside Towers will increase our profits further.
The total amount of water may remain the same due to people extended the time to shower.
d. Drawing a conclusion that is too board in degree or scope
- The following appeared in the editorial section of a local newspaper. The probability of Croesus Company, recently restored to private ownership, is a clear indication that businesses fare better under private ownership than under public ownership.
Even if most businesses that return from public to private status improve their profitability
(fare better) as a result, the author's conclusion that private businesses as an entire group face
better than public ones is far too broad. Perhaps the most profitable businesses are the ones
that remain public ones forever. If so, then the author would need to narrow his conclusion
accordingly.
e. Relying on vague or ambiguous evidence
- The following appeared as part of an article in the business section of a daily newspaper.Company A has a large share of the international market in video-game hardware and software. Company B, the pioneer in these products, was once a $12 billion-a-year giant but collapsed when children became bored with its line of products. Thus, Company A can also be expected to fail, especially given the fact its games are now in so many American homes that the demand for them is nearly exhausted.
The mere fact that Company A's products appeared in " so many " American homes
accomplishes little toward showing waning demand for its products, let alone toward showing
that the company will fail. To begin with, the term " so many " is too vague to be statistically
meaningful. Even if by " so many " the author means " nearly all ", perhaps among Americans,
the demand for more new Company A games is strong. Moreover, the author ignores foreign
markets, which might account for a significant portion of Company A's sales. The greater the
demand outside America, the less likely Company A will fail.
f. Arguing simultaneously for two competing objectives
- The following appeared as part of an article om a popular science magazine. Scientists must typically work 60 to 80 hours a week if they hope to further their careers; consequently, good and affordable all-day child care must be made available to both male and female scientists if they are to advance in their fields. Moreover, requirements for career advancement must be made more flexible so that preschool-age children can spend a significant portion of each day with a parent.
In essence, the second assertion serves to undermine the first one. If the children of scientists
spend significant time each day with a parent, without compromise to the scientists-parent's
career, then all-day child care would seem unnecessary - in direct contraction to the author's
first assertion. Thus, the author must either reconcile the two assertions or choose one
assertion over the other.
g. Irrational Appeals
Include : Appeal to Authority, Emotion, Personal Observation (Experience) ...
h. Ad Hominem
i. Straw Argument
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