We have learned this week about deductive reasoning, including what it takes for an argument to be valid. This discussion allows us to get more practice with the concept through making arguments valid. You will see a list of arguments here. These arguments are not presented in standard form, and each is missing a premise that would be necessary to make it valid. Your tasks will be to put the argument into standard form and add the missing premise that would validly link the premises to the conclusion.
Prepare: To prepare to respond to this prompt, reread the section from Chapter 2 of our book titled “Extracting Arguments in Standard form,” all required portions of Chapters 3 and 4, as well as the guidance and required media for this week. Further assistance in the filling missing premises can be gained from the document How to Construct a Valid Main Argument and the video Constructing Valid Arguments.
Reflect: Look at the list of argument options below. Choose an argument that has not yet been chosen by any of your classmates. Think through the reasoning and determine what premise is (or premises are) missing that would be needed to make the argument valid. You might also consider challenging yourself by choosing from the more difficult examples in the list (at the bottom).
Choose from the following list of argument options.
1. Flipper is a dolphin, so Flipper is a mammal.
2. Football is dumb because it is a waste of time.
3. If he loved you he would have shown up on time with flowers. He must not love you.
4. All mammals bear live young, so dragons are not mammals.
5. Abortion kills a human being, therefore abortion is wrong.
6. He broke the record for rushing yards in a game on that last play. Therefore he holds the record.
7. He won the election. So he will be the next governor.
8. He won’t go to the wedding since he doesn’t like mushy stuff and weddings are mushy.
9. I can’t go to the movies with you – I have a test tomorrow and I have to study.
10. Mike loves pickles. Pickles come from cucumbers. Therefore Mike loves cucumbers.
11. You shouldn’t go out with that guy. He rides a motorcycle and goes to bars.
12. Capital punishment is wrong because it is killing and it doesn’t save anyone’s life.
13. You shouldn’t use drugs because they are addictive and can ruin people’s lives.
14. To fix your care you will need money. However, to have money you have to have money. It appears that you need to get a job.
15. To go to the movie you have to have a ticket. To buy a ticket you must pay money. Thus, to go the movie you must pay money.
16. If you don’t do your chores then you can’t have any dessert. You really like dessert, so you will certainly do your chores.
17. You will get an A if you study hard and always come to class. You came to class every time and studied. You are bound to get an A.
18. Julie is allergic to gluten. So she won’t be having any bread.
19. Only women can have babies, so women are more important to the survival of the species.
20. If I wear that cologne then women will love me. I bought that cologne, so women are going to love me.
21. I can’t go to the party because there will be alcohol there, and I am a Mormon.
22. You shouldn’t force me to wear a seat belt because that would violate my rights.
23. In order to buy a car you will need money. But to have money you need to get a job. But to go to a job you will need to be able to get to work. So you will not be able to buy a car.
24. Capital punishment kills a human being. It is wrong to kill a human being except in self-defense. So capital punishment is wrong.
25. You shouldn’t tell someone to do something unless you would be willing to do it yourself. You’ve never gone to war. So you shouldn’t vote for others to go to war.
26. If you talk to Mike about politics then he will yell at you. If he yells at you then you will be hurt and it will damage your friendship. Therefore, you shouldn’t talk to Mike about politics.
27. Either the maid or the butler did it. For the butler to have done it he would have had to have been at the mansion yesterday. The butler was away all day yesterday. So, the maid did it.
28. If the maid was guilty then she would have had to been at the scene during the crime. However, she was seen a mile away only minutes before the crime, and she has no car. She must be innocent.
29. It is always wrong to kill a human being unless it is necessary to save somebody’s life. Abortion kills a human being. So abortion is wrong unless the mother’s life is in danger due to the pregnancy.
30. Government intervention is justified if it is necessary to protect the welfare of the people and does not violate anyone’s constitutional rights. Therefore, government intervention is justified in this specific case because it is necessary to protect the welfare of the people.
Write: In your original post, be sure to include the entire original argument, in standard form, with your own added premise (or premises) in bold. After you have presented the argument, include a description of how the conclusion logically follows from the premises. Include also a reflection on whether it seems that the missing premise(s) is likely to be true (in the context). Would there be any way to fix the argument so that it is valid and has all true premises?
Guided Response: Read the reflections of your classmates and analyze the arguments that they have presented, paying close attention to how the conclusion follows from the premises. In particular, if you believe that their argument is still technically invalid, explain a way in which it would be possible for the premises to be true and the conclusion false. If you think that their argument is valid, then address the question of whether the premises all seem to be true and how it might be improved. If someone presents such a suggestion for your own argument, then respond by attempting to revise the argument so that it is valid and has all true premises.