Critical reasoning

What is critical reasoning?
❖ Critical reasoning includes the dispositions to:
❖ Seek alternative hypotheses, explanations, conclusions, plans,
and sources.
❖ Endorse a position that is justified by the information that is
available
❖ Be well acquainted with the available information.

Who are critical thinkers?
• Present a position honestly and clearly, theirs as well
as others'. This includes the dispositions to
✓ Be clear about the intended meaning of what is
said, written, or otherwise communicated,
seeking as much information and precision as
the situation requires
✓ Determine, and maintain focus on the
argument given
✓ Seek and offer reasons for their
opinions/conclusions

Steps in Critical Reasoning
(Deconstruction of Argument)
• Analyze arguments:
1. Identify premises
2. Identify unstated reasons
❑ (Assumptions)
1. Identify conclusions
2. Identify and handle superfluousness
3. See the overall structure of an argument
4. Summarize

What is premise?
• A premise is a sentence offered as a reason
for reaching the conclusion.
• e.g.:
• It is Friday. Wioletta always wears jeans
on Friday, so Wioletta will be wearing
jeans today.

What is conclusion?
• Conclusion is based on premises (and
assumptions).
• e.g.:
• It is Friday. Wioletta always wears jeans
jeans today.

What is argument?
• An argument is:
• a set of sentences.
• .... one of them is being said to be true, and
• the others are being offered as reasons for
believing the truth of the one.

What is an argument?
• It is almost the entire situation that’s built
up. e.g.:
• It is Friday. Wioletta always wears jeans on
Friday, so Wioletta will be wearing jeans
today.
• Stan was driving his truck over the speed
limit. He had no excuse for driving over the
speed limit. Furthermore, he was
intoxicated. Therefore, Stan was breaking
the law.

What is assumption?
• Assumption is something that
is accepted as true or certain to happen, but
it has no proof.
Twelve Types: Unrecognised, unstated,
unquestioned, naive, pragmatic, productive,
unproductive, predictions, pessimistic,
optimistic, likely facts, and sour grapes.

Conti…
• In the following argument:
• “It is Friday. Wioletta always wears jeans
jeans today.”
• ….., it could be assumed that:
• Wioletta doesn’t wear jeans on the other
days.
• People wear particular dresses on particular
days/occasions.

Let’s have another example.
• Manchester is north of Oxford and
Edinburgh is north of Manchester;
therefore, Edinburgh is north of Oxford.
• The assumption is:
• Edinburgh can’t be in the East, South or
West of Oxford.

Let’s have one more example of
assumption.
• A CEO of a major company noted a serious
decline in worker’s productivity during the
previous five years. According to a report
given by an outside consultant, productivity
dropped by 35% by the end of that period.
The CEO has therefore initiated a plan to
boost productivity by giving employees
shares of the company as part of their pay
package.

Conti…
• Assumption:
• Owning something or to be a part of
something obliges you to work harder to
make it successful.

Conti…
• Premise(s) + Assumption(s) = Conclusion
(Reasonably acceptable assumption)

Types of Critical Reasoning
Questions
1. Weaken the Argument
2. Strengthen the Argument
3. Find the Assumption
4. Draw Inference
5. Find the Conclusion
6. Paradox Questions

Weaken the Argument
• There are two ways in which an argument can be
weakened:
• I. An option that weakens the argument can directly
disprove the assumption.
• 2. Any new information given in an answer choice
that makes the assumption less likely to be correct
will weaken the argument as a whole.
• e.g. The cellular service quality got dropped
significantly in India. Ten years ago, there were no
instances of call drop or disconnectedness. There is
also a decrease in the speed and reliability of
service.

• Which option does weaken the argument?
• A. The volume of connections handled by the mobile
operators has increased dramatically over the last ten
years.
• B. Unprecedented increases in the cost as well as scarce
availability of spectrum for mobile services have put
severe pressures on the mobile companies.
• C. Mobile services have diversified from carrying mere
voice data to a whole range of internet data such as
downloading, video-calling, and data sharing.
• D. The opposition to negative externality of cellular
radiation has obstructed increase of network services in
response to the increasing subscriber base.

Strengthen the Argument
• If the correct answer can confirm the
assumption by mentioning an experiment,
survey or any other proof and help the
assumption appear to be true, then it will
support the main argument.

Strengthen the Argument
• Pakistan and Bangladesh have suffered
defeats at the hands of Indian cricket team.
India will defeat them in tennis as well.
• The option that strengthens the argument is:
• A. India has been losing to them also.
• B. It is not necessary what happened in cricket, that
will also happen in tennis.
• C. India has been defeating them for the past ten years.
• D. Both A and B

Find the Assumption
• Questions on assumption will ask you to
select the answer choice with the
information that must be true (‘the̳
assumption’) for the given argument to be
accurate.

Find the Assumption
• Last year, support for the social and behavioural sciences represented
only three percent of the government‘s total budget for research funds
in the United States. Thus the sharp reductions imposed particularly
on such programmes this year seem to be dictated not by financial
constraints but by social philosophy.
• Which of the following is an assumption on which the conclusion
of the above passage is based?
• Government funding is the primary source for research in the US.
• The social and behavioural sciences are as valuable as physical and
biological sciences.
• Three per cent is an insignificant portion of the government‘s total
budget for research funds.
• The government funds allocated for research in the social and
behavioural sciences are not sufficient for the work that needs to be
done.

Assumption
e.g.
 You should marry Radha because she has the same temper as you
have.
Premise : She has the same temper as you have
Conclusion : You should marry Radha
Assumption : People with same temper should get married.

Statement: 4 out of 5 doctors recommended
brand X types of chocolates to their sugar
eating patients.
• Conclusion A: 80 % doctors recommend
brand X chocolates.
• Conclusion B: Brand X chocolates are
considered to be good for health by the
doctors.

• Statement: A recent study shows that children
below 5 in the cities of the developing nations
die mainly of diarrhoea and parasitic intestinal
worms.
• Action 1: Governments of the developing
nations should take adequate measures to
improve the hygienic conditions in the cities.
• Action 2: Children below 5 in the cities of
developing nations should be brought under
continuous medication.
• Being a responsible citizen, which action
will you prefer?

• Statement: A recent study shows that
children below 5 in the cities of the
developing nations die mainly of diarrhoea
and parasitic intestinal worms.
• Action 1: Governments of the developing
nations should take adequate measures to
improve the hygienic conditions in the
cities.
• Action 2: Children below 5 in the cities of
developing nations should be brought under
continuous medication.

Draw Inference
• For inference questions, you must draw conclusions
only from the information you are directly given in
the passage.
• e.g.
• Shakespeare: Some of the productions of my plays by
a non-professional theatre are poorly performed, and
such interpretations do not provide a true measure of
my skills as a dramatist.

Inference conti…
• Which one of the following can be properly inferred from the
preceding statement?
• (A) Some non-professional theatre group productions of
Shakespeare’s plays provide a true measure of his skills as a dramatist.
(B) All non-professional theatre group productions of Shakespeare’s
plays that are not poorly done provide a true measure of his skills as a
dramatist.
• (C) All of the productions of Shakespeare’s plays by non-professional
theatre groups that do not provide a true measure of his skills as a
dramatist are poorly done.
(D) If a production of a dramatist’s play is well done, then it provides
a true measure of his/her skills as a dramatist.
• (E) At least some non-professional theatre group productions of
Shakespeare’s plays fail to provide a true measure of his skills as a
dramatist.

Inference conti…
• Which one of the following can be properly inferred from the
preceding statement?
• (A) Some non-professional theatre group productions of
Shakespeare’s plays provide a true measure of his skills as a
dramatist.
(B) All non-professional theatre group productions of Shakespeare’s
plays that are not poorly done provide a true measure of his skills as a
dramatist.
• (C) All of the productions of Shakespeare’s plays by non-professional
theatre groups that do not provide a true measure of his skills as a
dramatist are poorly done.
(D) If a production of a dramatist’s play is well done, then it provides
a true measure of his/her skills as a dramatist.
• (E) At least some non-professional theatre group productions of
Shakespeare’s plays fail to provide a true measure of his skills as a
dramatist.

Paradoxical Questions
• Paradoxical/discrepancy questions will ask
you to choose the answer choice that
explains the paradox (self-contradiction) in
the given argument.

• In 2009, there was a sharp increase in the return of
people who were reported to have died in the
country during the first week of the year,
compared with the first week of the previous ten
years... . There was no epidemic spreading through
the country at that point in time. Moreover, most
of the deaths were not among the young and could
not even be attributed to binge drinking in
celebration of the new year.

• Which of the following can best explain the
discrepancy?
• The government announced in 2008 that estate taxes, payable by
the heirs on someone's death, would be abolished effective from
the new year.
• Astrologists predicted that 2009 was a good year to die in, for
salvation of the soul.
• The data is an anomaly that has no logical explanation.
• The price of some cancer drugs and chemotherapy increased by
10% in January 2009, making treatment more expensive than
before.
• An earthquake in one of the cities during December 2008 made
hospital care availability more difficult for regular illnesses.

Paradoxical Questions Conti…
French cuisine is famous for its frequent and
liberal use of cream and cheese, both high in
saturated fat. For years, medical studies have
shown the strong correlation between diets high in
saturated fat and coronary heart disease, and yet,
France has a much lower incidence of such
disease than found in comparable countries like
the United States.

• Which of the following can best explain the French paradox?
• (A) Certain kinds of cheese can have as much as five times the
amount of saturated fat that cream has.
• (B) People in the United States, per capita, eat almost the same
amount of saturated fat on average as do people in France.
• (C) The United States imports more cheese from France than from any
other country.
• (D) Red wine, typically served with French food, helps to clean the
build-up of fats in the arteries, reducing the risk of heart disease.
• (E) It is typically for a French person to have either cream or cheese at
each of the three meals in a day.

Let’s discuss one more example
of a paradoxical situation.
• The exchange rate between the currency of Country X and that of
Country Y has historically favored the currency of Country Y.
Because of this, citizens of Country Y often take their vacations in
Country X, where the exchange rate makes hotels and restaurants
more affordable. Yet, citizens of Country Y rarely purchase
clothing or electronics in Country X, despite the fact that those
items are more expensive in their home country, even when sales
taxes are taken into account.
• Which of the following, if true, would best explain the buying
habits of the citizens of Country Y?

Let’s discuss one more example of a
paradoxical situation…Conti…
• Which of the following, if true, would best explain the buying
habits of the citizens of Country Y?
• A. Citizens of Country Y prefer the fashions available in their own
country.
B. Stores in Country X receive the latest fashions and technology
several months after they are available in Country Y.
C. The citizens of Country X believe in the buying power of the
currency of Country Y.
D. The government of Country Y imposes tariffs on imported
goods.
E. The currencies of Country X and Country Y are both weak
compared to the currency of Country Z.

Questions with Different Wording
• Sue: Commercial flights currently contribute more
carbon dioxide to the atmosphere in one year than does
the whole of Africa. If we want to reduce global
warming, we need to restrict the number of flights we
take.
• Dave: Do you know that by taking one inter-continental
flight you cause more pollution than you will in twelve
months of car travel?
• Dave’s response to Sue’s comment serves to

Dave’s response to Sue’s comment serves to
• A. reinforce Sue’s contention that flights are a major
contributor to increased carbon dioxide levels
B. add more weight to her contention that we should
reduce the number of flights we take
C. mitigate the force of her argument by suggesting that
there is an alternative approach
D. suggest an alternative that will reduce the effect of
pollution
E. question whether she really understands the severity of
global warming

• Since Dave’s comments don’t challenge what Sue
says, we can eliminate answers E and C (mitigate
= lessen). His comments reinforce what she says
and so A sounds tempting but is wrong since Dave
talks about pollution in general and doesn’t
mention carbon dioxide. Of the remaining choices,
B is best since Dave does give information that
suggests, like Sue, that we should take fewer
flights. (D is incorrect mainly because Dave is not
talking about the effect of pollution.

• The committee on sexual discrimination in the
workplace has highlighted the Supremo of the
company as a chief offender. Out of the twenty
senior executives in the firm, only one is a
woman; and out of the forty junior executives,
only five are female.
The Supremo could best defend itself against
the charges by showing that:

The Supremo could best defend itself
against the charges by showing that:
• A. Male and female executives at the same level
have the same qualifications
B. They pay the same salary to senior men and
senior women
C. Ten times more men than women apply for jobs
with the company
D. The work pressures and long hours make jobs
with the company unattractive to married women
E. All job applicants who were rejected had fewer
qualifications than those accepted

• Recent studies have highlighted the harmful
effects of additives (colors, preservatives,
flavor enhancers etc.) in food . There are no
synthetic substances in the foods we produce at
Munchon Foods. We use only natural
ingredients. Hence you can be sure you are
safeguarding your family’s health when you
buy our products.
• Which of the following, if true, would most
weaken the contention of Munchon Foods?

Which of the following, if true, would most
weaken the contention of Munchon Foods?
• A. Some synthetic substances are not harmful
B. Some natural substances found in foods can be
harmful
C. Food without additives is unlikely to taste good
D. Munchon Foods produces only breakfast cereals
E. Without preservatives some foods could cause
harm

• A fruit known as amla in certain parts of Asia is
an excellent source of vitamin C. A small
quantity of the fruit grated and added to salads
provides almost all the daily requirement of this
vitamin. However, the fruit is very sour. A new
process designed to remove most of the sour
taste will make the fruit acceptable to American
tastes. We are therefore starting to grow this fruit
for sale in the United States.

The argument above assumes all of
the following except
• A. Americans generally won’t eat very sour
foods.
B. The new process does not remove a
significant part of the vitamin content
C. That a market exists for a new source of
vitamin C.
D. The fruit can be used only in salads.
E. Apart from being sour there are no other
objections to eating this fruit.

Critical reasoning

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