Deductive and Inductive Flashcards

A student argues: 'My three friends all failed this professor's class. This professor must be an unfair grader.' This argument is BEST described as:

Answer: A hasty generalization — a weak inductive argument

Generalizing from only three cases to a conclusion about the professor's grading overall is a hasty generalization, a weak inductive argument.

Which is the correct form of modus tollens?

Answer: If P then Q; not Q; therefore not P

Modus tollens takes the form: If P then Q; Q is false; therefore P is false — a valid deductive form.

An argument by analogy concludes that because two things share several properties, they share another property. This type of reasoning is:

Answer: A form of inductive reasoning that varies in strength

Analogical reasoning is inductive because its conclusions are probable based on shared features, not logically guaranteed.

Consider: 'Whenever pressure increases in a gas, temperature rises (in a sealed container). We increased the pressure. Therefore the temperature rose.' This is:

Answer: A valid deductive argument from a scientific law

Applying an established law (the premise) to a specific case and deducing the outcome is deductive reasoning.

What does it mean to say that deductive arguments are 'truth-preserving'?

Answer: If the premises are true, a valid deductive argument guarantees the conclusion is true

Truth-preserving means valid deductive reasoning cannot lead from true premises to a false conclusion.

Which of the following would WEAKEN an inductive generalization the most?

Answer: Discovering that the sample is biased or unrepresentative

A biased or unrepresentative sample undermines the foundation of an inductive generalization, making it much weaker.

Which correctly identifies a difference between inductive and deductive reasoning regarding certainty?

Answer: Deductive reasoning yields necessary conclusions; inductive reasoning yields probable ones

In valid deductive reasoning the conclusion is necessarily true given true premises; inductive conclusions are only probably true.