Inference Flashcards

A scientist observes that every swan seen over 200 years has been white. Which inference is most logically sound?

Answer: All swans observed so far in this dataset have been white.

Inductive generalizations from observation are limited to the evidence gathered; they do not guarantee universal truth.

An insurance company charges higher premiums to drivers under 25. This practice is most likely based on what kind of inference?

Answer: Statistical data show higher accident rates for drivers under 25.

Actuarial pricing relies on statistical group patterns rather than assumptions about any individual driver's character.

A doctor says, 'The X-ray suggests a fracture.' The word 'suggests' indicates:

Answer: The evidence points toward a fracture but is not conclusive.

Hedging language like 'suggests' signals a probabilistic inference that the evidence supports but does not prove.

If the premises 'All fish have gills' and 'Sharks are fish' are both true, the conclusion 'Sharks have gills' is:

Answer: A valid deductive inference that must be true if premises are true.

This is a valid syllogism: the conclusion follows necessarily from the two true universal premises.

A wine expert tastes a wine and infers it is from a specific region based on its flavor profile. This is an example of:

Answer: Inference to the best explanation based on sensory evidence.

The expert draws the most plausible conclusion that explains the observed evidence, a form of abductive reasoning.

A survey asks 500 college students about sleep habits and reports results as representing 'all Americans.' This inference is flawed because:

Answer: College students are not a representative sample of all Americans.

Generalizing from a non-representative sample to a broader population commits the fallacy of hasty generalization.

Premises: 'If the power is out, the alarm won't sound. The alarm sounded.' What can be inferred?

Answer: The power was not out.

Using modus tollens: if the alarm sounded, the condition that would have prevented it (power outage) did not occur.