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Argument Analysis and Diagramming II




  • Bracket all propositions
  • Number bracketed propositions according to their order of occurrence in the argument
  • Circle premise and conclusion indicators (but not other connective or transitional terms)
  • Diagram the logical structure of the argument


1. Deductive Arguments

  • Argument based on mathematics
  • Argument from definition
  • Categorical syllogism
  • Hypothetical syllogism
  • Disjunctive syllogism

2. Inductive Arguments

  • Prediction
  • Argument from analogy
  • Inductive (empirical) generalization: universal (UG) and statistical (SG)
  • Argument from authority
  • Argument based on signs
  • Causal inference
  • Statistical syllogism
  • Simple enumeration


1. Mathematically-challenged adult: Since x + y = 10, and x = 7, it follows that y = 5.

2. Concerned parent: Jane will never be able to solve that difficult problem in advanced calculus in the limited time allowed. She has never studied anything beyond basic algebra, and even in that she earned only a D. Moreover, all she does is party from Thursday night to Sunday night.

3. Former President Bill Clinton: Welfare programs are intended to help poor people, but existing programs are not helping: they encourage poor unmarried women to have babies, they discourage poor people from seeking jobs, and they perpetuate a habit of dependence. The welfare system should consequently be reformed.

4. Education merchandise telemarketer: An encyclopedia is a very valuable possession for a family to own. For adults, it’s a quick reference tool. For children, it provides a form of learning that complements what they receive in school. Why? Because in school they have to follow a structured program, whereas an encyclopedia lets them go from topic to topic following their own curiosity.

5. Young basketball fan: Either Kobe Bryant is guilty of sexual assault or his alleged victim is mentally unstable. But Kobe Bryant is not guilty of sexual assault. Consequently, his alleged victim is mentally unstable.

6. Problem-solving CCRI logic student: Since my car won’t start, I’ll have to take the bus, so I need to take exact change for the fare.

7.  Anti-trust federal prosecutor: It is rarely economical for two cable companies to lay cables in the same area. For this reason, they do not directly compete with each other. This suggests that cable TV is a natural monopoly, and should therefore be regulated by the government.

8. RISD Student: Graffiti art has several advantages over art entombed in museums. It can function as a vital part of a living environment, typically in urban settings. Accordingly, the everyday person going to work or out jogging can experience it in the context of his or her daily activities. Therefore, on this basis, graffiti art challenges the average citizen to consider its social and cultural criticism.

9. Anti-cult activist: All religious cults require members to obey the leader without question. However, an autonomous person would never obey a religious cult leader without question. So, there are no autonomous individuals in religious cults.

10. Thomas Sepe, CCRI President: Academic cheating impedes one’s educational development because it means relying on someone else’s knowledge, whereas the precise purpose of education is to learn how to rely on your own knowledge.

11. MADD (Mothers Against Drunk Drivers) activist: Getting teenagers drunk in order to teach them their driving limitations is like using Russian roulette to teach gun safety. It’s dangerous to use Russian roulette to teach gun safety since someone might get killed. Similarly, getting teenagers drunk in order to teach them their driving limitations is dangerous.

12. Citizens bank promoter: Citizens bank is committed to serving you. We have recently made a multimillion-dollar investment in data processing equipment. We are open more hours per week than any of our local competitors. Our automatic teller is open twenty-four hours a day, seven days a week. And our staff consists only of certified professionals.

13. The terms good and bad do not refer to objective qualities independently belonging to a thing since one and the same thing may be good, bad, and indifferent at the same time. For a particular piece of music may be good for someone who is celebrating, bad for someone who is in mourning, and neither good nor bad for someone who is deaf.
                                                              —adapted from Benedict Spinoza, The Ethics (1677)

14. Educational theorist: If Jeanne studies a foreign language this semester, then she’ll learn how the structure of language can affect the way we think. And, as it turns out, Jeanne will be studying French this semester. Therefore, Jeanne will learn how the structure of language can affect the way we think.

15. TV exercise guru: Regular exercise strengthens muscles, helps the cardiovascular system, and lowers cholesterol. Therefore, if you want to be healthy, you should exercise regularly.

16.  Fundamentalist Islamic cleric: History will prove that the infidel United States unfairly demonized our brother in Allah, the venerable Osama bin Laden. For one thing, the United States conveniently neglects to mention brother bin Laden’s numerous acts of compassion toward the oppressed and homeless Palestinian refugees. Nor do they mention his steadfast financial support of the Islamic clergy, which clearly indicates his profound religious nature. Also, America is—as the great Ayatollah Khomeini once proclaimed—the great Satan. Consequently, anything it says is vicious propaganda and lies.

17. Carl Everett, professional baseball player: The shadows in the Apollo photos seem to point in different directions. Accordingly, artificial lighting was used when taking the pictures. So, the Apollo photos were taken in a studio on Earth.  Therefore, it is not true that the Apollo astronauts landed on the moon.

18. Prison chaplain: Mr. McVeigh, if you do not survive death, then at the moment of death you will not be conscious. But if we do survive death, then you will be born into new life. Therefore, if you are executed for mass murder you have nothing to fear.