Philosophy: Logic, Fallacies, and Everyday Arguments
Evaluating reasons, evidence, and common mistakes in reasoning
Philosophy: Logic, Fallacies, and Everyday Arguments
Evaluating reasons, evidence, and common mistakes in reasoning
Philosophy - Grade 9-12
- 1
Decide whether the passage contains an argument. Passage: Everyone in the school should have access to clean drinking water. The water fountains in the east hallway have been broken for two months, and many students cannot afford to buy bottled water every day.
Look for a claim that the speaker is trying to support with reasons.
The passage contains an argument. The conclusion is that everyone in the school should have access to clean drinking water, and the reasons are that the fountains are broken and some students cannot afford bottled water. - 2
Identify the conclusion in this argument: If students are expected to complete online homework, then the school should make sure all students have reliable internet access. Some students do not have reliable internet access at home. Therefore, the school should provide a way for those students to get online.
The conclusion is that the school should provide a way for students without reliable internet access to get online. The earlier statements give reasons for that claim. - 3
Identify the premise or premises in this argument: The city should add more bike lanes because biking reduces traffic, lowers pollution, and gives residents a healthy way to travel.
Premises are the statements offered as support.
The premises are that biking reduces traffic, lowers pollution, and gives residents a healthy way to travel. These reasons support the conclusion that the city should add more bike lanes. - 4
Determine whether the argument is deductive or inductive. Explain your answer. Argument: Every mammal is warm-blooded. A dolphin is a mammal. Therefore, a dolphin is warm-blooded.
The argument is deductive because the conclusion is meant to follow with certainty from the premises. If the premises are true, then the conclusion must be true. - 5
Determine whether the argument is deductive or inductive. Explain your answer. Argument: I have seen five movies by this director, and all of them had surprise endings. The director's next movie will probably have a surprise ending too.
Ask whether the conclusion must be true or is only likely to be true.
The argument is inductive because the conclusion is probable rather than guaranteed. It uses a pattern from past movies to make a prediction about a future movie. - 6
Test the validity of this argument form: If it rains, then the game will be canceled. It is raining. Therefore, the game will be canceled.
The argument is valid. It has the form modus ponens: if P then Q, P, therefore Q. If the premises are true, the conclusion must be true. - 7
Test the validity of this argument form: If I study, then I will improve my score. I improved my score. Therefore, I studied.
The conclusion reverses the if-then statement. Check whether another cause could produce the same result.
The argument is invalid. It commits the fallacy of affirming the consequent because there could be other reasons the score improved, such as easier questions or extra sleep. - 8
Name the fallacy in this argument and explain it: You should not listen to Maya's opinion about the school dress code because she always wears old sneakers.
This is an ad hominem fallacy. The argument attacks Maya personally instead of addressing her reasons or evidence about the dress code. - 9
Name the fallacy in this argument and explain it: Everyone is buying the new phone, so it must be the best phone available.
Popularity can be evidence of interest, but it is not the same as proof.
This is a bandwagon fallacy. The argument assumes that a phone is best just because many people are buying it, but popularity does not prove quality. - 10
Name the fallacy in this argument and explain it: If the school allows students to redo one assignment, soon students will expect to redo every assignment, then deadlines will disappear, and grades will become meaningless.
This is a slippery slope fallacy if no evidence is given that the first step will actually lead to all the extreme results. The argument jumps from one limited policy to a chain of dramatic consequences. - 11
Name the fallacy in this argument and explain it: We should either spend all of the club budget on a party or cancel the club entirely.
Look for missing middle options.
This is a false dilemma fallacy. The argument presents only two choices even though other options may exist, such as saving some money, planning a smaller event, or fundraising. - 12
Name the fallacy in this argument and explain it: The cafeteria food made me tired today. I ate lunch, and then I felt sleepy during class, so lunch must have caused it.
This is a questionable cause fallacy, also called post hoc reasoning. The argument assumes that because sleepiness happened after lunch, lunch caused it, but other factors could explain it. - 13
Create a simple argument map for this passage by listing the conclusion and two supporting reasons. Passage: The school library should stay open later during exam week. Many students need a quiet place to study after sports and jobs. Also, some students do not have a reliable internet connection at home.
Put the main claim at the top, then place the supporting reasons underneath it.
The conclusion is that the school library should stay open later during exam week. One supporting reason is that many students need a quiet place after sports and jobs. Another supporting reason is that some students do not have reliable internet at home. - 14
Revise this weak argument so it is stronger and fairer: Homework is pointless because my friend hates it and teachers just want to make students miserable.
Remove insults, add evidence, and make the claim more specific.
A stronger version could be: Some homework assignments may not help students learn when they are repetitive or disconnected from class goals. Teachers should design homework that gives meaningful practice and feedback. This version gives a clearer claim and avoids attacking teachers' motives. - 15
Evaluate this everyday argument for strength. Passage: The new park rules should allow dogs on leashes. In nearby towns with leash rules, dog-related complaints have stayed low. Leashed dogs are easier for owners to control, and allowing them would let more residents enjoy the park. Is the argument strong or weak? Explain your answer and name one piece of additional evidence that would help.
The argument is fairly strong because it gives relevant reasons and uses examples from nearby towns. More evidence would help, such as data about dog-related incidents in this park or survey results from residents who use the park.