Crit 111 Homework 1.4: Deductive & Inductive Arguments

The following statement, "An argument is valid if and only if it is impossible for any argument to have that form and to have all true premises and a false conclusion," is:

True

Suppose an argument is invalid. Which of the following must be true?

It is possible to accept the premises but, at the same time, reject the conclusion.

Given that a particular argument is invalid, which of the following is NOT true?

The premises cannot all be true while the conclusion is false.

Given that a particular argument is invalid, which of the following is true?

It is possible for all of the premises to be true and the conclusion false.

The following statement, "An argument is valid when it is possible for any argument to have that form and to have all true premises and a false conclusion," is:

False

The following statement, "An argument is invalid if and only if its specific form is invalid," is:

True

The following statement, ""An argument is invalid if and only if its specific form is valid," is:

False

The following statement, "A conclusion is true or false, but not both," is:

True

Consider the following argument: Litmus paper reacts to acidic solutions by turning red. It looks to me as if that glass of liquid has a piece of red paper in it. So, the liquid in that glass is probably acidic. Suppose the premise "I am wearing glasses with red-tinted lenses" is added. What effect would this have on the argument?

The additional premise would weaken the argument

Consider the following argument: There are one hundred blue marbles and fifty green marbles in this bag. Deniz picks a marble out at random. So it's safe to conclude that Deniz picked out a blue marble. Suppose the premise "Deniz's favorite color is green" is added. What effect would this have on the argument?

The additional premise would have no effect upon the argument

Consider the following argument. My desktop computer must be broken. It won't power on when I press the button. Suppose the premise "No other electrical equipment in the room is working" is added. What effect would this have on the argument?

The additional premise would weaken the argument

Consider the following argument. Christian is reliable and hard-working. He has been at the company for five years. So, Christian will get the promotion. Suppose the premise "Christian is a Red Sox fan" is added. What effect would this have on the argument?

The additional premise would have no effect upon the argument

Consider the following passage: Lady Logica is the best superhero in the world! The reason is that she's the only superhero who can reason her way out of any situation, and only the best superhero in the world can reason themselves out of any situation! This passage...

contains an argument that is best classified as deductive

Consider the following passage: Children learn best in a safe, welcoming environment. One way to achieve such an environment is to have lots of brightly colored posters on the walls. Another way is to have bowls of candy placed around the classroom. But when I tried that last year, the parents sent letters of complaint to the principal. This passage...

does not contain an argument

Consider the following passage: CCTV footage of the crime scene revealed that the killer was a white woman with a large build. The only such women with access to the crime scene when the crime was committed were Ms. Smith and Mrs. Jones. So if the killer isn't Ms. Smith, it has to be Mrs. Jones. This passage...

contains an argument that is best classified as deductive

Consider the following passage: Percy and Sons quoted us $40,000 for the renovation job. Churley, Churley and Chruley quoted us $30,000. Dad is a notorious penny pincher. But Mum's friend Carol personally recommended Percy and Sons. I'm pretty sure Percy and Sons will get the job. This passage...

contains an argument that is best classified as inductive

Consider the following passage. Smoking cigarettes is the cause of about 5,000,000 deaths in the USA each year. Smoking is an entirely voluntary activity. We should disqualify cigarette smokers from health insurance programs to lower premiums for non-smokers. After all, nonsmokers should not be held liable for other people's voluntary, health-endangering behavior. This passage...

contains an argument; the third sentence is its conclusion

Consider the following passage. Just last year, some children teased a baboon and were mauled. Teasing dangerous animals is likely to get you injured. That polar bear is dangerous. Thus, you should not tease that polar bear. This passage...

contains an argument; the fourth sentence is its conclusion

Consider the following passage. Cutting the grass is good for you. When you cut the grass, you get exercise. You also get fresh air. Fresh air and exercise are good for you. This passage...

contains an argument; the first sentence is its conclusion

Consider the following enthymeme: Little Bobby only gets awful nightmares if he has seen a horror movie with his friends. He knows he's not allowed to see them anymore. But judging from last night, he must have seen a scary movie. Which of the following premises should be added to create a charitable reconstruction of the argument?

Little Bobby had awful nightmares last night

Consider the following enthymeme: I cannot believe Sam stole your money. I have known him for years. Which of the following premises should be added to create a charitable reconstruction of the argument?

Sam has never stolen anything that I am aware of.

Consider the following argument: All bakers are vegetarians. No bakers are cops. Hence no cops are vegetarians. What is the logical form of this argument?

All B are V

No B are C

------------

No C are V

Consider the following argument: All bakers are vegetarians. No bakers are cops. Hence no cops are vegetarians. Which of the following substitutions demonstrates that the argument is invalid?

B = squares

V = shapes

C = circles

Consider the following argument: Some politicians are Democrats. Barack Obama is a politician. Therefore, Barack Obama is a democrat. What is the logical form of this argument?

Some P are D

x is P

-----

x is D

Consider the following argument: Some politicians are Democrats. Barack Obama is a politician. Therefore, Barack Obama is a democrat. Which of the following substitutions demonstrates that the argument is invalid?

P = Cities

D = Capitals

x = Bridgewater