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PHILO103-23G (NET) Critical Thinking

Assignment 1

10% of final grade

Complete all five parts of the assignment and submit your assignment answers through Moodle.

You can write on this document and upload it. Remember to save your changes and upload the completed version.

Note that you must submit your assignment in a format which can be read by Feedback Studio (Turnitin): Word, PDF, and Rich Text Format formats are all readable.

Part A [20 marks]

For each of the following arguments, say whether it is valid or invalid.

Give a brief explanation of why. (Your explanation should say something specific about the particular argument, rather than just being a definition of validity – though it may be useful to also give a definition of validity.)

1. P1. The long-tailed bat was NZ’s Bird of the Year for 2021.

P2. If something is not a bird, then it cannot be the Bird of the Year.

C. The long-tailed bat is a bird.
Valid or invalid?
Why?

I think it is valid, because the premises of P1 and P2 can be deduced to the conclusion that the long-tailed bat was named the New Zealand Bird of the Year in 2021, so the long-tailed bat must be a kind of bird.

2. P1. Some children are intelligent and thoughtful.

P2. All intelligent and thoughtful people should be allowed to vote.

C. Some children should be allowed to vote.

Valid or invalid?

Why?

      Valid, because P1 said that children are smart and thoughtful, and P2 said that all smart and thoughtful people should be allowed to vote, so the conclusion is established.

3. P1. Some adults are neither intelligent nor thoughtful.

P2. All intelligent and thoughtful people should be allowed to vote.

C. Some adults should not be allowed to vote.

Valid or invalid?

Why?

Valid, the premise of P1 says that some adults are neither smart nor considerate, combined with P2 that all smart people should be allowed to vote, corresponds to the conclusion that certain adults should not be allowed to vote.

4. P1. Either the current restrictions on foreign ownership of houses in Aotearoa will be loosened, or the new government will be unable to fund the tax cuts it has promised.

P2. The new government will fund the tax cuts it has promised.

C. The current restrictions on foreign ownership of houses in Aotearoa will be loosened.

Valid or invalid?

Why?

      Invalid, This is the fallacy of affirmative consequences.

5. P1. Some animals that are not indigenous to Aotearoa are destructive both to native forests and to orchards.

P2. Some animals that are destructive both to native forests and to orchards can legally be poisoned or trapped.

C. Some animals that are not indigenous to Aotearoa can legally be poisoned or trapped.
Valid or invalid?
Why?
Valid, because this is a hypothetical syllogism.

Part B  [15 marks]

For each of the following arguments, insert an implicit premise which will make the argument valid. (Make sure that each of the stated premises remains relevant – that is, don’t add a premise that makes the existing premises unnecessary.)

1. P1.  It is immoral for anyone except God to decide the time of a person’s death.

P2._Euthanasia can determine the time of a person's death.____________________________

C. Euthanasia is morally wrong.

6. P1. If I don’t get an A+ for PHILO103, I won’t have an A average.

      P2. If I don’t have an A average, I won’t get into second-year law.

P3._I needed to enter my second year of law school._______________________________

C. I need to get an A+ for PHILO103.

P1) Either UFOs are alien vessels visiting from another world, or they are optical illusions.
P2)
_UFOs are not alien spacecraft from another world.________________________
C) UFOs are optical illusions..

Part C [10 marks]

Draw an argument tree for each of the following arguments. The easiest way to draw diagrams is to draw them on a piece of paper, photograph them with your phone, and paste the photo into the document. But if you prefer, you can use the Microsoft Word draw tools.

1. P1. You should avoid doing anything that increases the likelihood of your catching Covid.

P2. Going to the party tonight would increase the likelihood of your catching Covid.

P3. The party is at Xavier’s place.

P4. Xavier’s parties are always boring.
C. You shouldn’t go to the party tonight.

                      

7. P1. If a parent is incapable of looking after their child, then their child should not live with them.
P2. Sarah’s mother is incapable of looking after her.
C1. Sarah should not live with her mother.
P3. If Sarah shouldn’t live with her mother, then she should live with her father. 
C2. Sarah should live with her father.

                  

Part D [40 marks]

Reconstruct the following arguments in standard form. Some of them may be extended arguments.

When you reconstruct them:

- make sure each premise and conclusion is a complete statement

- label your premises and conclusion, and use an inference bar

- insert any implicit premises and/or intermediate conclusions that are needed

- omit any irrelevant material.  

1.  No great leader appeals to anything as intangible as “kindness” to get people to comply with emergency restrictions, so obviously Jacinda Ardern was not a great leader.

P1: No great leader would resort to something as intangible as “goodwill” to get people to comply with emergency restrictions.

P2: Jacinda Ardern did this

C: Jacinda Ardern is not a great leader.

2.  Nakedness should not be permitted on free-to-air television during the day. That is a time when children might see it, and they should not be exposed to nudity.

P1: Children may see nudity while watching free TV programs during the day.

P2: Children should not be exposed to nudity.

C: Nudity is not allowed on free daytime television.

3.  Either Ethel continues to live at home, or she moves into a rest home. It is better to avoid moving into a rest home unless absolutely necessary. If Ethel has adequate home help, then she can stay where she is. So we should make sure Ethel has adequate home help.

P1: Ethel can either continue to live at home or move into a nursing home

P2: Unless absolutely necessary, it is best to avoid moving into a nursing home.

P3: If Ethel has enough family help, then she can stay where she is.

C: It should be ensured that Ethel has adequate family help.

4. All cats kill birds, unless they are either kept inside all the time or made to wear a bell. Keeping cats inside all the time is not practicable.  We should make every cat wear a bell.

P1: All cats kill birds unless they are kept inside or forced to wear bells.

P2: It is impractical to keep cats indoors all the time.

C: We should let every cat wear a bell.

5. Anyone who goes boating without a life jacket is an idiot! Life-jackets are basic safety sense, and anyone who ignores basic safety is an idiot.    

P1: Life jackets are basic safety awareness.

P2: Anyone who ignores basic safety is an idiot.

C: Anyone who goes boating without a life jacket is an idiot!

Part E [15 marks]

For the following argument,

A. Sketch the basic structure of the argument. (The basic parts of the stated argument have been numbered for your sketch.)

B. Reconstruct the argument and put it into standard form, following the guidelines for reconstruction. Note that you may need to add an unstated intermediate conclusion.

C. Draw a tree diagram of the final standard form reconstruction you end up with.

(To understand what to do, you will need to have completed lessons on tree diagrams and on reconstruction, including watching the videos.) The easiest way to draw diagrams is to draw them on a piece of paper, photograph them with your phone, and paste the photo into the document - or you can use the Microsoft Word draw tools if you wish.

(1) Either David killed the Bain family or Robin did.  (2) If Robin did it, his fingerprints would have been found on the gun. (3) Robin’s fingerprints were not found on the gun. So (4) David killed the Bain family.

A: This is Disjunctive syllogism, (p or q, not p, therefore q).

B:

P1: Either David killed the Bain family, or Robin did.

P2: If Robin did this, his fingerprints would be found on the gun.

P3: Robin's fingerprints were not found on the gun.

C1: David killed the Bain family.

C：