Inductive Reasoning and Scientific Method
What the exam tests
Inductive reasoning and scientific method cover probabilistic support, generalization, analogy, causal inference, and hypothesis testing. The exam tests whether you can distinguish induction from deduction and identify the method used in a described investigation.
Core rules
- Induction is ampliative: premises make the conclusion probable, not certain. Strength varies with sample size, representativeness, and background evidence.
- Enumeration by simple induction generalizes from observed cases; analogy argues from shared properties to a further similarity.
- Mill’s methods: agreement (find the common factor), difference (remove the factor and see the effect disappear), agreement and difference, concomitant variation, residues.
- Scientific method: observation/problem, hypothesis, prediction, experiment or further observation, confirmation or refutation, revision.
- A hypothesis is testable if it forbids some observable outcomes; ad hoc rescue should be treated with caution.
Worked example
Five people who ate at a restaurant develop food poisoning; all five ate coleslaw, while the other diners did not. Using the method of agreement, the investigator identifies coleslaw as the common antecedent and frames the hypothesis that it was the cause. The reasoning is inductive: it supports the hypothesis without proving it. A controlled comparison-diners who ate coleslaw versus those who did not-would use the method of difference and strengthen the causal claim. The conclusion should be stated as probable, not deductively certain.
Traps
Do not call an inductive argument valid or invalid in the deductive sense; use strong/weak. Avoid post hoc ergo propter hoc: temporal succession is not causation. A small or biased sample cannot support a sweeping generalization. Correlation alone does not establish causation. Do not treat a confirmed prediction as proof of a hypothesis, since rival hypotheses may predict the same result.