Critical Thinking

PHI10003 / PHI60001 Critical Thinking

FALLACIES

In Questions 1 to 4, say which of the following fallacies has been committed and explain how it is committed:

Hasty generalisation

Post hoc

Ad hominem

Circular reasoning

Slippery slope

Appeal to ignorance

Red Herring

Question 1

The tax rate has gone up and the failure rate of new business has gone up. Clearly, higher taxes are causing business failures.

Question 2

Cycling is not a very effective way of losing weight. My friend Gabriel frequently cycles long distances, but he is quite overweight.

Question 3

My cousin said I should be careful not to become a compulsive gambler because it will hurt me and my family; but he’s a drug addict—so I don’t trust what he says anymore.

Question 4

“Fracking”, technically known as “induced hydraulic fracturing”, is a process for extracting natural gas by injecting water and chemicals deep into the ground. The pressure causes the shale and other rock to fracture, releasing the gas. Some people have argued against fracking on the grounds that it can cause earthquakes and that the chemicals used might contaminate drinking water supplies. However, these worries are unjustified, as natural gas produces much less carbon dioxide than coal and is therefore a key part of the strategy to combat climate change.

STANDARDISATION

Question 5

Standardise this argument

There are several reasons why (1) the Government should not give handouts to the car industry. (2) If car manufacturers are not successful, it is not the responsibility of the taxpayer to pay money for them to become more innovative and efficient. Furthermore, (3) the car industry is not a major employer, since (4) it employs fewer people than many other industries. Finally, (5) rather than propping up the declining car manufacturing industry, the Government would be better off creating new jobs in clean energy.

COUNTER-CONSIDERATIONS

Question 6

Think of a counter-argument against the argument given in Question 5. Include as many counter-considerations as you can think of.

DEDUCTIVE ARGUMENTS

Which of the following arguments is an example of the invalid pattern Denying the Antecedent?

If a then b, Not a, Therefore Not b

1. If Greece defaults on its loans, that will make it harder for the government to borrow money. And if that happens, it will not be able to afford to run public services. So, if Greece defaults on its loans, public services will have to be shut down.

2. If speed cameras actually prevented traffic accidents, they would be justified. But they don’t seem to prevent traffic accidents, so they are not justified.

3. The brake lights on my car have stopped working. The problem is either with the fuses or the light globes. I’ve inspected the fuses and they are fine, so the globes must be faulty.

4. If carbon dioxide in the atmosphere is causing global warming, then we should expect to see temperatures increasing steadily over the last 100 years. But although temperatures have risen, the rise has not been steady, so it cannot be carbon dioxide that is causing global warming.

ARGUMENTS USING ANALOGY

Question 7

Car owners have to obtain a license to prove they can safely operate a car and must register their cars every year. They must also obey speed limits and not drive while under the influence of alcohol and drugs, else they will lose their licence to drive. So, gun owners too should be required to register their guns, pass safety and background tests, and not use their guns in ways that endanger people—if they don’t, they should lose the right to own a gun.

(a) What is the Primary Subject of this argument, and what is the Analogue?

(b) The argument claims there are similarities between the two cases; are these similarities (i) positively relevant, (ii) negatively relevant, or (iii) irrelevant?

(c) If there are relevant differences between the two cases, will they be (i) positively relevant or (ii) negatively relevant?

LANGUAGE AND ARGUMENT

Question 8

What’s wrong with the following argument?

The weasel arguments of our opponents are too slimy, and their proposals too disgusting for decent people to countenance. My good friends, you must vote against those vile proposals.

1