"Nearly everyone in my class has bought this brand of phone, so it must be the best phone available." The reasoning is flawed because it:

attacks the people who disagree instead of their reasons

offers only two options when more exist

assumes that one event caused another because it came first

"The economist's proposal to simplify the tax code should be rejected. He was fined last year for a traffic offence." The reasoning is flawed because it:

assumes the conclusion it is trying to prove

relies on the opinion of an unqualified authority

draws a general conclusion from a single example

"Either we ban all private cars from the city centre, or we accept that the air there will never improve." The reasoning is flawed because it:

concludes that one event caused another because it followed it

treats a claim as true because many people believe it

misdescribes the opposing position to make it easier to attack

"The school's examination results improved in the year after the new principal joined. The new principal is therefore the reason for the improvement." The reasoning is flawed because it:

uses a key word in two different senses

generalises about all schools from one school

attacks the previous principal's character

"This newspaper always reports the truth. We know this because the newspaper itself says so in its editorial, and whatever the newspaper says is true." The reasoning is flawed because it:

confuses a necessary condition with a sufficient one

relies on a sample that is too small

predicts a chain of consequences without support

"I have met three lawyers, and two of them were rude to me. Lawyers are rude people." The reasoning is flawed because it:

presents only two possibilities when more exist

assumes that rudeness causes people to become lawyers

attacks an opponent's position that nobody holds

Anita says that homework for primary school children should be reduced. Bharat replies: "So Anita thinks children should learn nothing at all and schools should stop teaching." Bharat's reply is flawed because it:

attacks Anita's character instead of her position

treats Anita's view as false because few people hold it

"If we allow students to retake one class test, they will soon demand to retake every examination, then to choose their own marks, and in the end a degree will be worthless." The reasoning is flawed because it:

concludes that something is true because an authority said so

treats two events that occur together as cause and effect

generalises from a small sample to a large group

"A famous cricketer has said in an advertisement that this investment scheme is completely safe. So the scheme is safe." The reasoning is flawed because it:

presents two options as the only ones

assumes the scheme is safe because many people have invested in it

attacks the critics of the scheme personally

"Every candidate who cleared the examination had studied hard. Riya has studied hard. So Riya will clear the examination." The reasoning is flawed because it:

relies on what most candidates believe

attacks Riya's character instead of her preparation

assumes that clearing the examination causes hard study

Logical Reasoning · Micro-test

Flaws in Reasoning: Logical Fallacies

CLAT's critical reasoning passages often ask what is wrong with an argument. The same dozen flaws come up again and again, and each has a recognisable shape.

10 questions · 5 minutes · instant scoring

What this topic actually tests

A flawed argument is one whose conclusion does not follow from its premises, whether or not the conclusion happens to be true. The flaws worth knowing by name are these. Ad hominem attacks the person making a claim instead of the claim. Appeal to popularity treats a belief as true because many hold it. Appeal to authority relies on someone who has no expertise in the matter. A false dilemma offers two options as if they were the only ones. Post hoc reasoning concludes that because one event followed another, the first caused the second. A hasty generalisation draws a conclusion about a whole group from a sample too small or unrepresentative to support it. Circular reasoning assumes the conclusion in one of its own premises. A straw man replaces the opponent's actual position with a weaker or more extreme one and attacks that. A slippery slope claims, without support, that one step will inevitably lead to a chain of others. And confusing a necessary condition with a sufficient one treats something that is required for a result as if it guaranteed the result. In the examination, the question is usually phrased as 'the reasoning is flawed because it…', and the options are descriptions, not names. So practise describing each flaw in plain words: 'attacks the speaker's character', 'assumes what it sets out to prove', 'treats two options as the only ones'.

The common trap on this topic

The first trap is choosing an option that describes a flaw in general but not the flaw in this argument. Several options will be genuine fallacies; only one is what the argument actually does. Test each option by asking whether you can point to the sentence in the argument where it happens. The second is confusing neighbouring flaws: post hoc reasoning needs a claim about cause, while a hasty generalisation needs a claim about a whole group. The third is rejecting an argument because its conclusion is false, or accepting it because the conclusion is true. A flaw is a defect in the route, not in the destination.

Flaws in Reasoning: Logical Fallacies: answers and explanations

"Nearly everyone in my class has bought this brand of phone, so it must be the best phone available." The reasoning is flawed because it:
Answer: B. treats the popularity of a choice as proof of its quality
The only support offered is that many people have chosen the phone. How widely something is chosen does not establish that it is the best; this is an appeal to popularity.
"The economist's proposal to simplify the tax code should be rejected. He was fined last year for a traffic offence." The reasoning is flawed because it:
Answer: C. attacks the character of the person instead of the merits of the proposal
A traffic fine has no bearing on whether the tax proposal is sound. The argument discredits the speaker in place of answering the proposal: an ad hominem.
"Either we ban all private cars from the city centre, or we accept that the air there will never improve." The reasoning is flawed because it:
Answer: B. presents two options as the only ones when others are possible
Cleaner fuels, congestion charges and better public transport are all ignored. Presenting two extremes as the only choices is a false dilemma.
"The school's examination results improved in the year after the new principal joined. The new principal is therefore the reason for the improvement." The reasoning is flawed because it:
Answer: A. assumes that because one event followed another, the first caused the second
The argument moves from sequence to cause. A new syllabus, a stronger batch or easier papers could equally explain the results; this is post hoc reasoning.
"This newspaper always reports the truth. We know this because the newspaper itself says so in its editorial, and whatever the newspaper says is true." The reasoning is flawed because it:
Answer: B. assumes the truth of the very claim it sets out to prove
The paper's own statement can prove its reliability only if we already accept that the paper is reliable. The conclusion is among the premises: circular reasoning.
"I have met three lawyers, and two of them were rude to me. Lawyers are rude people." The reasoning is flawed because it:
Answer: D. draws a conclusion about a whole group from a sample too small to support it
Three people cannot stand for an entire profession. This is a hasty generalisation.
Anita says that homework for primary school children should be reduced. Bharat replies: "So Anita thinks children should learn nothing at all and schools should stop teaching." Bharat's reply is flawed because it:
Answer: A. replaces Anita's actual position with a more extreme one and attacks that
Anita proposed less homework, not no learning. Bharat answers a position she did not take: a straw man. He does not attack her character, so it is not an ad hominem.
"If we allow students to retake one class test, they will soon demand to retake every examination, then to choose their own marks, and in the end a degree will be worthless." The reasoning is flawed because it:
Answer: D. claims without support that one step will lead inevitably to a series of extreme consequences
No reason is given for why each step must follow from the one before. An unsupported chain of consequences is a slippery slope.
"A famous cricketer has said in an advertisement that this investment scheme is completely safe. So the scheme is safe." The reasoning is flawed because it:
Answer: C. relies on the opinion of a person who has no expertise in the subject
Fame in cricket gives no special knowledge of investment risk. The argument appeals to an authority who is not an authority on the matter.
"Every candidate who cleared the examination had studied hard. Riya has studied hard. So Riya will clear the examination." The reasoning is flawed because it:
Answer: D. treats something required for success as if it were enough to guarantee success
The premise makes hard study necessary for clearing the examination; it does not say everyone who studies hard clears it. The argument confuses a necessary condition with a sufficient one.

FAQ

Do I need to know the Latin names of fallacies for CLAT?

No. CLAT describes flaws in plain words in the options. The names are useful only as labels to organise your own revision.

What is the difference between a necessary and a sufficient condition?

A necessary condition must be present for the result but does not guarantee it; a sufficient condition guarantees the result. Registering is necessary to vote; it is not sufficient, since you must also turn up.

How are flaw questions different from weaken questions?

A flaw question asks what is wrong with the reasoning as it stands. A weaken question asks which new fact, if true, would make the conclusion less likely. The first is about structure; the second adds information.

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