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RMIT University Library - Learning Lab

Critical thinking activity



Identify the faulty reasoning in the following statements. Click 'Check Answer' after each question.

Faulty reasoning:

Example 1

If you want better education you have to raise taxes. If you don’t want to raise taxes you can’t have better schools.
a. Presents two options when others exist.
b. Uses a threat to persuade.
c. I don't know, tell me.

Correct answer is (a).
It looks like there are only two choices (raise taxes or not improve education). Often these can appear as reasonable logic. If there other alternatives to your arguments, don’t ignore them – instead, explain why they should be ruled out.

Tip: Be aware of arguments that seem to offer only opposing positions. Usually these arguments use excluding forms of language, such as the words, ‘either’ and ‘or’. This is called a 'false dichotomy'.

Example 2

The Prime Minister doesn’t have any children. She isn’t a mother so how can she make decisions about what’s best for families.
a. Presents a personal attack.
b. Asks a rhetorical question.
c. I don't know, tell me.

Correct answer is (a). This argument focuses attention on the person (her family status) rather than evidence of her decision-making ability.

Tip: Be sure to stay focused on the argument. This type of reasoning can appeal to our emotions, values and beliefs in order to persuade. This is called a 'ad hominem'.

Example 3

The number of fatal shark attacks in Australia has increased 150% in the last decade. Australian beaches are very dangerous and you are likely to be attacked by a shark if you go swimming.
a. Assumes a result based on experience and observation.
b. Uses a small number of cases to support a general claim.
c. I don't know, tell me.

Correct answer is (b). In this instance, an assumption about a likelihood of an event occurring (deaths at Australian beaches) has been based on what are actually very small numbers (4-5 shark attacks in 2015 compared with 1-2 in 2014). The writer has changed the reporting of the evidence to support their claim.

Tip: Ensure you have enough relevant and credible evidence to support your claims and you are not just overgeneralising. This is called a 'hasty generalisation'.

Example 4

Banning guns is ridiculous. More people are killed by cars each year but nobody talks about banning cars.
a. Compares two elements which are not alike in relevant aspects.
b. Assumes a single action will lead to undesirable consequences.
c. I don't know, tell me.

Correct answer is (a). Many arguments try to compare objects, ideas, or situations. If the two things aren’t alike in the relevant aspects (e.g. the usual function of guns and cars), the relevance and reliability of the argument is weak.

Tip: Identify what is important to your claim. Are the two things you’re comparing really alike in the key aspects? This is called a 'weak analogy'.

Example 5

There has been an increase in crime in the area. More families are moving into the suburbs and young people should have access to sports grounds to keep them off the streets.
a. Assumes a cause and effect relationship between two events.
b. Applies the traits of a small group to a large group.
c. I don't know, tell me.

Correct answer is (a). Just because there seems to be a relationship linking events or a trend doesn’t mean it is ‘cause and effect’. Don’t assume that because B comes after A, A caused B (i.e. more young people in the area leads to more crime).

Tip: If you say that A causes B, you need to have evidence that shows A caused B or it could just be a coincidence. This is called a 'false cause'.

Example 6

If I don’t pass my university course then I won’t graduate. If I don’t graduate I won’t get a good job and if I can’t get a good job my parents will think I’m a complete failure.
a. Assumes a causal relationship between two events.
b. The contention does not follow from the evidence.
c. I don't know, tell me.

Correct answer is (b). A series of connected statements which lead to an unreasonable and usually negative consequence. It is often used in emotional appeals rather than logical arguments.

Tip: Check your argument for chains of consequences. Make sure these connections are supported by evidence. This is called a 'slippery slope'.