Logical Fallacies

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# Logical Fallacies - PowerPoint PPT Presentation

Logical Fallacies. 8 th grade ELA. What is a logical fallacy?. Definition: a mistake in reasoning. Used when trying to make an argument and the use of bad logic makes the point invalid QUESTION: Which of the following is a logical fallacy?

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## PowerPoint Slideshow about 'Logical Fallacies' - nhi

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### Logical Fallacies

What is a logical fallacy?

Definition: a mistake in reasoning.

Used when trying to make an argument and the use of bad logic makes the point invalid

QUESTION: Which of the following is a logical fallacy?

• All men are mortal; Mr. Morgan is a man; therefore, Mr. Morgan is a mortal
• All men are mortal; Mr. Morgan is mortal; therefore, Mr. Morgan is a man
• Bonez is stupid; Bonez is a Pekingese; therefore, all Pekingese are stupid.
• Bonez is stupid; Bonez is a Pekingese; therefore, some Pekingese are stupid.

Definition: A question which contains an assumption

EX: Police have in custody someone they suspect of robbery. They bring the victim by and ask the suspect, “Is this the woman you robbed?” This is a leading question because it assumes that he robbed someone. A non-leading question would have been, “Did you rob this woman?”

Question: Explain what is assumed with this leading question: “Did you enjoy spoiling the dinner for everyone else?”

Question: Identify if the question is leading or not. If so, explain what is assumed.
• "Have you stopped cheating on your taxes?"
• "Are you happy with the mess your interruption has created?"
• "Are you happy with the job that the repairmen have done?"
False Assumptions
• Definition: when an author assumes a relationship between factors that leads to a conclusion the factors do not support
• Sometimes a false assumption may be true. Sometimes the premise (a statement given to support an argument) may be true. HOWEVER, the issue is the logic of the argument. The conclusion being drawn is not logical based on the premise. The assumption made is false even if the conclusion is true.
• Which sentence is a false assumption? A. Ice cream sales increase in the summer. B. Violent crimes increase during the summer. C. Ice cream causes violent crimes.
False Assumptions
• There have been studies done on milk. From whymilk.org (the Got Milk? People who are actually the California Milk Processor board [hint, hint, they are trying to sell milk to make money!]): “Research suggests teen milk drinkers are less likely to suffer from type 2 diabetes as adults”
• What is the false assumption they want people to make?
• What are some other factors NOT being addressed that would prevent the false assumption?
False Assumptions

(Osmosis is when a molecules can actually move through cell walls.)

What is Garfield’s false assumption?

Definition: when a word has a judgmental connotation; meant to bias (prejudice) the reader

Question: Explain why “pro-life” and “pro-choice” are both loaded terms.

Question: During WWII, the Nazis had “labor camps”. Today we call them for what they were “death camps” and “concentration camps.” They also called the people in these camps “prisoners”, but in truth, most were not criminals and were used as slave labor. Additionally, Hitler came up with “The Final Solution”, which really meant the extermination and murder of the Jewish people and Slavic groups. Think back to The Giver, what Loaded Terms were used similar to the Nazis? How did these loaded terms make the people of the community feel?

Incorrect Premises

Definition: when a premise (a statement given to support an argument) is untrue and the conclusion may be untrue as a result.

EX:

• All men are green. (premise)
• Mr. Morgan is a man. (premise)
• Therefore, Mr. Morgan is green. (conclusion)

Question: How is the above premise incorrect?

Note: notice the logic actually makes sense, but since we are basing logic on something untrue, the conclusion becomes untrue.

Incorrect Premises
• If the streets are wet, it has rained recently. (premise)
• The streets are wet. (premise)
• Therefore it has rained recently. (conclusion)

Question: How is the above premise incorrect?

Note: notice the logic actually makes sense, but since we are basing logic on something untrue, the conclusion becomes untrue.

Caricature

Definition: attributing to all members of a group beliefs and practices which are caricatures of the most extreme positions taken by anyone in the movement attacked

EX: Pitt bulls are killers.

Question: Why is the above a caricature?

Note: Caricature is commonly used against people of a certain religion (or similar group). However, all the caricatures I could think of were things I would never want to say, even if it was just to illustrate a point. But I do feel the need to inform you that the nature of caricatures is quite hateful. I’m sure you can think of non-religious examples as well, such as certain political parties, people from certain countries, etc. Remember though, these are not just stereotypes. This is basing a whole group on the actions of a minority within that group.