Critical Thinking: Argument Evaluation

Study Notes

Claims: Statements that express a belief or opinion
Premises: Statements that provide evidence or support for a claim
Inferences: Conclusions drawn from premises
Argument structure:
1. Identify the claim
2. Identify the premises
3. Identify the inference(s)
4. Evaluate the relationship between premises and claim
Argument evaluation criteria:
- Validity: Does the argument follow logically?
- Soundness: Are the premises true and the argument valid?
- Strength: How well do the premises support the claim?

Formal fallacies: Errors in the argument's structure or form
Informal fallacies: Errors in the argument's content or reasoning
Common fallacies:
- Ad hominem: Attacking the person instead of the argument
- Ad populum: Appealing to popularity instead of evidence
- False dichotomy: Presenting only two options when there are more
- Slippery slope: Assuming a chain of events will occur without evidence
- Straw man: Misrepresenting an opponent's argument

Inductive arguments: Conclusions drawn from specific observations or data
Inductive strength: The degree to which the premises support the conclusion
Inductive leap: The step from observing patterns to making a general claim
Inductive reasoning examples:
- Analogies: Comparing two things to argue they share a common property
- Mill's methods: Systematically eliminating alternative explanations
- Statistical reasoning: Drawing conclusions from data analysis

Deductive arguments: Conclusions that follow necessarily and with absolute certainty from the premises
Deductive validity: The guarantee that the conclusion follows from the premises
Deductive reasoning examples:
- Syllogisms: Arguments with two premises and a conclusion
- Categorical logic: Reasoning with categories and classifications
- Propositional logic: Reasoning with statements and their relationships

An argument consists of claims, premises, and inferences.
Claims are statements that express a belief or opinion.
Premises provide evidence or support for a claim.
Inferences are conclusions drawn from premises.
To evaluate an argument, identify the claim, premises, and inference, and assess the relationship between premises and claim.
Argument evaluation criteria include validity, soundness, and strength.
Validity refers to whether the argument follows logically.
Soundness requires true premises and a valid argument.
Strength is how well the premises support the claim.

Inductive arguments involve drawing conclusions from specific observations or data.
Inductive strength refers to the degree of support the premises provide for the conclusion.
Inductive reasoning involves making an educated guess or "inductive leap" from observations to a general claim.
Examples of inductive reasoning include:
- Analogies: comparing two things to argue they share a common property.
- Mill's methods: systematically eliminating alternative explanations.
- Statistical reasoning: drawing conclusions from data analysis.

Deductive arguments involve conclusions that follow necessarily and with absolute certainty from the premises.
Deductive validity guarantees that the conclusion follows from the premises.
Examples of deductive reasoning include:
- Syllogisms: arguments with two premises and a conclusion.
- Categorical logic: reasoning with categories and classifications.
- Propositional logic: reasoning with statements and their relationships.

A valid argument form to arrive at a logical conclusion, also known as "denying the consequent"
Structure:
- If P, then Q (premise)
- Not Q (premise)
- Therefore, not P (conclusion)
Example: If it's raining, then the streets will be wet. The streets are not wet. Therefore, it's not raining.
Reliable way to infer the negation of the antecedent (P) from the negation of the consequent (Q)
Often used to eliminate possibilities or arrive at a negative conclusion

A valid argument form to arrive at a logical conclusion, also known as "affirming the antecedent"
Structure:
- If P, then Q (premise)
- P (premise)
- Therefore, Q (conclusion)
Example: If you study hard, then you will pass the exam. You studied hard. Therefore, you will pass the exam.
Reliable way to infer the consequent (Q) from the affirmation of the antecedent (P)
Often used to arrive at a positive conclusion or confirm a hypothesis

Both modus tollens and modus ponens are valid argument forms, ensuring the conclusion is true if the premises are true
Modus tollens is used to arrive at a negative conclusion, while modus ponens is used to arrive at a positive conclusion