Critical Thinking and Ethics Lecture Review

Lecture notes: Evaluating Philosophical and Moral Arguments

• Context and course schedule (Module 1: Critical Thinking and Ethics)

  • Argument analysis worksheet due Friday at 11:59 PM.
  • Wednesday topic: fallacies and biases.
  • Monday, Sept 29: Reading Quiz 1 on subjectivism by Julian Driver and egoism and moral skepticism by James Rachel.
  • Goal: learn to identify, map, and evaluate arguments; understand what makes an argument strong or weak.

• Big-picture motivation

  • Critical thinking is underemphasized in many educational systems; modern times push for more careful engagement with issues that matter in daily life.
  • Higher education should be a venue for the free exchange of ideas and constructive argumentation, not just assertion.
  • The ability to evaluate arguments helps us discern what to believe and how to respond in disagreements, debates, or everyday decisions.

• What is an argument? basic definitions

  • An argument is a piece of reasoning offered in support of the truth of a claim.
  • A claim, or statement, is an assertion that something is the case or is not the case; it can be true or false.
  • A standalone question, command, greeting, or exclamation is not an argument.
  • In everyday text, arguments can be woven into narrative background information; the argument itself is the reasoning that supports a claim.
  • In practice, arguments consist of:
  • A main claim (the conclusion),
  • One or more supporting claims (premises or reasons).

• Key terms: statements, claims, conclusions, premises

  • Statement/claim: an assertion that something is or is not the case; can be true or false.
  • Conclusion: the main claim that follows from the premises; what the argument is trying to establish.
  • Premises: the reasons or supporting claims given for the conclusion.
  • Mapping arguments: identify conclusion first, then premises; then check logical connection.

• Indicators of premise and conclusion

  • Premise indicators (signal that what follows is a reason):
  • because, since
  • Conclusion indicators (signal that what follows is a conclusion):
  • therefore, so
  • Important caveats
  • The word "so" can be ambiguous; context is needed to determine if it signals a conclusion.
  • Practical use: when you see a premise indicator (e.g., "because"), what follows is a reason; when you see a conclusion indicator (e.g., "therefore"), what follows is the conclusion.

• Mapping a simple argument (example: slavery)

  • Text: "Slavery is wrong because it deprives another human being of the right to freedom."
  • Identification:
  • Conclusion: Slavery is wrong.
  • Premise: It deprives another human being of the right to freedom.
  • Alternative ordering:
  • Premise: Slavery deprives … of the right to freedom.
  • Conclusion: Slavery is wrong. (Introduced by "Therefore" or "So".)
  • One-sentence argument: conclusions and premises can appear in the same sentence.

• Examples used to illustrate argument structure

  • Pepperoni on pizza:
  • Premise: Pepperoni makes me sick.
  • Conclusion: We should not get pepperoni on the pizza.
  • Indicator word: because (tells you what follows is the premise).
  • One-sentence form: Pepperoni makes me sick, therefore we should not get pepperoni on the pizza.
  • Capital punishment example:
  • Premise indicator: because
  • Conclusion: Capital punishment is morally permissible.
  • Premise: It helps deter crime.
  • Mapping shows how conclusions can be at the start or end of a sentence depending on word order.
  • Conditional (If–Then) argument:
  • If John killed Bill in self defense, then he did not commit murder.
  • Premise: John did kill Bill in self defense.
  • Conclusion: Therefore, he did not commit murder.
  • Important: when mapping, include the if–then clause as part of the premises.
  • Sherlock Holmes example (implied premise):
  • Explicit premise: The dog did not bark.
  • Implied (well-known) premise: Dogs bark at strangers.
  • Conclusion: The thief was no stranger to the dog.
  • Mapping: Dogs bark at strangers (implied); The dog did not bark (explicit); Therefore, the thief was no stranger to the dog.
  • Note: implied premises are often well-supported general facts; you may need to acknowledge them in analysis.
  • All pigs can fly example (valid but not sound):
  • Premises: All pigs can fly; Anything that can fly can swim.
  • Conclusion: Pigs can swim.
  • This is logically valid (if premises were true) but not sound because the premises are false.
  • Inadequate premises can make a valid argument unsound:
  • Example: Cost-effectiveness claim in capital-punishment debate may be false; if a premise is false, the argument remains valid but not sound.
  • Invalid argument example (Jill–Jeff–Kathy):
  • Premises: Jill loves Jeff; Jeff loves Kathy.
  • Conclusion: Jill loves Kathy.
  • This is invalid because the conclusion does not logically follow from the premises.

• Inductive vs deductive arguments

  • Deductive arguments: aim for guaranteed truth of the conclusion if premises are true; validity matters.
  • Example: All men are mortal; Socrates is a man; Therefore, Socrates is mortal. (Deductive, valid, and sound.)
  • Inductive arguments: aim for probable support; conclusions are likely but not guaranteed.
  • Valid vs sound distinction (recap):
  • Valid: the conclusion follows logically from the premises (structure only, does not consider truth of premises).
  • Sound: the argument is valid and the premises are actually true.
  • An argument can be valid but not sound if a premise is false.
  • An argument can be invalid even if many premises are true.

• Common pitfalls and nuanced points

  • Even if the conclusion follows logically, you must assess the truth/acceptability of the premises (often requires evidence or data).
  • The presence of an implied premise requires asking whether it is a well-known or established fact.
  • A paragraph in a text may be background or narration; the actual argumentative core is the set of statements that support the conclusion.
  • One-sentence premises and conclusions are common, but longer arguments have multiple premises and possibly intermediate conclusions.

• The steps in analyzing an argument (process from the lecture)
  1) Identify the conclusion using conclusion indicator words or strong claims (e.g., a moral obligation, a claim about what is true).
  2) Identify the premises (the reasons given in support of the conclusion).
  3) Determine if the conclusion follows logically from the premises (the logic condition).

  • Formally: if the premises were true, would the conclusion necessarily be true?
  • Notation: the relationship can be expressed as P1 \,\land\, P2 \,\land\, \dots \,\land\, Pn \rightarrow C or equivalently {P1, P2, \dots, Pn} \models C. 4) Determine if the premises are true or acceptable (often requires research or evidence; some premises require data to verify). 5) Determine if there are any faults in the reasoning (to be explored in the next class: fallacies and biases).
    • If you confirm step 3 (logical connection) but step 4 fails (premises are false), the argument is valid but not sound.
    • If step 3 fails, the argument is invalid regardless of premises.

• Practical exam preparation notes (context for your worksheet)

  • Your worksheet will be about identifying the conclusion, identifying premises, and evaluating whether the conclusion follows logically from the premises.
  • You will also evaluate the truth/acceptability of the premises and comment on strengths and weaknesses of the argument.
  • Expect to encounter a mix of one-sentence arguments and longer, multi-premise arguments; pay attention to premise indicators and conclusion indicators.

• The broader goal for your course meetings

  • Friday: complete argument analysis worksheet.
  • Wednesday: cover fallacies and biases to prepare for deeper analysis.
  • Readings ahead: On the quiz, focus on subjectivism and egoism/moral skepticism as assigned.
  • Upcoming lectures will finish the current topic and introduce fallacies and biases, then move to new material.

• Quick takeaway checklist for evaluating any argument

  • Step 1: What is the conclusion? (look for indicators and strong claims)
  • Step 2: What are the premises? (the reasons given)
  • Step 3: Does the conclusion logically follow from the premises? (logic condition)
  • Step 4: Are the premises true/acceptable? (needs evidence or data)
  • Step 5: Are there any fallacies or faulty reasoning patterns?
  • Remember: an argument can be valid but unsound if a premise is false; it can be sound only if both it is valid and all premises are true.

• Final note from the session

  • The instructor plans to finish lecture three (philosophical argumentation) and then move to lecture four on fallacies and biases in the next class.
  • The argument-analysis portion of the course remains a central focus through the upcoming sessions.

• Encourage questions and practice

  • If you’re unsure, try mapping an argument you encounter in readings or everyday life by identifying C, P1, P2, etc., and then test logical connection and premise truth.
  • Use the if–then form when needed to preserve conditional structures in your maps.

• Remember the math/logic notations used here

  • Logical entailment form: P1 \,\land\, P2 \,\land\, \dots \,\land\, P_n \rightarrow C
  • Logical entailment shorthand: {P1, P2, \dots, P_n} \models C