Logical Fallacies

Logical Fallacies

In this unit, we will look at some of common types of logical fallacy that people commit in arguments. Knowing about logical fallacies has two benefits:

1)    It makes you less likely to commit them in your arguments

2)    It helps you to rebut arguments made by your opponents.

Task 1

Read the following seven statements. Put a tick (√) next to the statements that seem reasonable to you.

 

In fact, all of these seven statements are illogical. Read the following discussion to see why.

1.    You have to finish your degree, or you won’t get a good job.

This is an example of a false dilemma. It suggests that there are only two alternatives. We can see that it is illogical by pointing out that a) some people finish their degree, but still do not get good jobs for other reasons, and b) some people (e.g. Bill Gates) have good jobs even though they didn’t go to university.

2.    Well, of course BC teachers say that a grasp of English is important in the Malaysia job market! That’s only because they’re English teachers!

This is an example of attacking the person – saying that an argument is untrue because of the character or the circumstances of the person speaking. The truth of a statement does not depend on who says it.

3.     Legalizing soccer gambling is a bad idea because if it happens, people will spend all their money on it, and they won’t have enough to pay their bills and they’ll start stealing in order to continue gambling.

This is known as a slippery slope argument. It involves the unreasonable assumption that a series of negative future consequences will definitely occur. Without more evidence, we cannot say that legalizing soccer betting will definitely lead to the consequences suggested.

4.    You can’t prove that the monster doesn’t exist, so it probably does.

This is an argument from ignorance. It implies that where there is no proof on one side, we can be sure that the other side is true. (Note: this works the other way as well – it is just as illogical to say, “You can’t prove that the monster exists, so it probably doesn’t”.)

5.    She deserves to pass the exam. She worked really hard, and she’ll be really upset if she fails.

This is an example of an appeal to pity. People who use this kind of statement are trying to substitute emotion for reasons. It’s a common way to discuss issues, but can have dangerous consequences, depending on the topic. Imagine, for example, if Osama Bin Laden were allowed into power simply because he “felt really sorry” for what he had done! In the case of exams, if everyone passed because we felt sorry for them, exam results would cease to have any meaning.

6.    All sensible people accept that free speech is a good idea.

This is an example of prejudicial language. The speaker is trying to “bully” others into accepting his/her position by implying that anyone who disagrees is not a “sensible person”.

7.    “The Matrix” must be a good movie. It sold millions of tickets.

This is an example of an appeal to popularity. It assumes that if many people think something is true, then it is. But what if the majority is wrong? There was, for example, a time when most people thought women were incapable of working outside the home.

Most of us, in day-to-day conversation, are guilty of one or more of these unreasonable ways of thinking. But in a debate, it is important to avoid this kind of poor logic, and to recognize it in your opponents’ speeches. It is also important to recognize when politicians, advertisers and other “professional liars” are using these techniques to convince us of false or illogical statements.

Task 2

There are many other types of faulty thinking. Match the following statements with the type of logical fallacy that they contain.

1. Universities are like business corporations, so their chief aim should be to make a profit.	a) False cause – assuming that if one thing happens, and then another thing happens, that the first caused the second
2. Few secondary schools in Malaysia use English as the medium of instruction. The English level is dropping. Therefore, English should be the medium of instruction in all schools in Malaysia.	b) Irrelevant conclusion – Even if two statements are true, it does not necessarily mean that they lead to a specific conclusion. A conclusion can only be drawn if there is a logical connection between the two statements.
3. I drank some green tea, and two days later, my back stopped hurting. What amazing powers that drink has!	c) Hasty generalization – allowing a few examples to “prove” a universal claim.
4. I’ve met twenty Koreans, and they all hate noodles. I guess noodles just aren’t popular in Korea.	d) False analogy – claiming that two things that are similar in some ways must be similar in all ways

1.	2.	3.	4.

Task 3

You have now learned about several different types of illogical thinking.

Work with a partner to compose seven statements, each one illustrating a different logical fallacy. Test your classmates on their ability to spot the problems in thinking.

1.

2.

3.

4.

5.

6.

7.

For more information on logical fallacies, have a look at these websites:

http://www.csun.edu/~dgw61315/fallacies.html#Why%20learn%20fallacies

http://www.nizkor.org/features/fallacies/

http://www.logicalfallacies.info/

http://www.onegoodmove.org/fallacy/toc.htm