Introducing Logic and Critical Thinking

The Skills of Reasoning and the Virtues of Inquiry


1. Introduction to Arguments

Exercise 1.1

A. Statement or Not a Statement?

Identify whether each of the following composes a statement or does not compose a statement. If it does not compose a statement, explain why it doesn’t.

  1. Your pants don’t match your shirt.
  2. Ask green whether to sake under feather.
  3. Why does water appear on the outside of a hot glass on a cold day?
  4. You will be important to everyone you meet.
  5. The square root of 169 is 17.
  6. Is this not a great day to be alive?
  7. Take what you want.
  8. You should explain why this composes a statement.
  9. If it isn’t broken, I’m not going to fix it.
  10. It’s going to be dry, or I’m going to stay inside.

B. Argument or Nonargument?

Identify whether each of the following quoted passages composes an argument. If a quoted passage does not compose an argument, identify whether it composes a report, a mere conditional statement, an illustration, or an explanation.

  1. A doctor says, “You have a hernia because you’ve been lifting excessive weights.”
  2. A stock analyst declares, “Tech stocks fell sharply today. FANG stocks—Facebook, Amazon, Netflix, and Google—each fell around 3 percent.”
  3. A conference summary states, “At the conference, many automakers announced that they will be developing new mobility platforms. Consumers in urban areas prefer not to own vehicles but instead to hire a vehicle service on demand. Automakers wish to supply that service.”
  4. A retail website states, “Checkout is quick and easy. Click on the ‘Pay Now’ button, and your stored credit card will be charged. There is no need to enter a new password or payment information each time.”
  5. A friend states, “We should talk on the phone. I’m feeling down, and I need someone to talk to. You’re always good at listening.”
  6. A wiring manual states, “If you don’t complete the circuit, there will be no power to the fixture.”
  7. An employer describes a drink-making procedure to a barista in training, “If you let the espresso shot sit more than thirty seconds, it becomes bitter. Sometimes baristas are tempted to pour their shots first, create foam, then pour the shot into the foam, but this leads to a bitter shot.”
  8. A reporter says, “The water in Flint, Michigan, has been contaminated for months. Lead from water pipes leached into the water supply, and the city has not yet taken the proper measures to filter the water.”
  9. A political blogger writes, “You’ll be accused of perjury if you lie on a witness stand.”
  10. A concerned parent writes, “You need to teach your child fire safety. My neighbors did not discuss fire safety with their child, and their child would have died in their house fire were it not for the fact that the fire department was nearly next door.”

Exercise 1.2

A. True or False?

Using your knowledge of the key vocabulary introduced in this section, determine whether the following statements are true or false.

  1. An invalid argument can have all true premises and a true conclusion.
  2. Some valid arguments have all false premises and a true conclusion.
  3. All strong arguments with a false conclusion have at least one false premise.
  4. All strong arguments with all true premises have a true conclusion.
  5. All sound arguments are strong.
  6. All valid arguments have all true premises.
  7. Statements can be cogent.
  8. Arguments can be either true or false.
  9. Some strong arguments have all false premises and a true conclusion.
  10. Any valid argument with a false premise is weak.

B. Practice with Arguments

Using your knowledge of key vocabulary introduced in this section, attempt to construct arguments with the features listed below.

  1. A valid argument with all false premises and a true conclusion.
  2. A valid but unsound argument.
  3. A weak argument with all true premises and a true conclusion.
  4. A strong argument with a false conclusion.
  5. An invalid argument with all true premises and a true conclusion.