Logic and Scientific Reasoning
Logic and Scientific Reasoning
This domain tests formal and informal reasoning: whether you can separate validity from truth, recognise argument forms, and explain how scientific hypotheses are tested. The exam often uses short arguments and asks you to identify the form or fallacy.
Core rules
- An argument has premises and a conclusion. Deductive arguments aim at validity: if premises are true, conclusion must be true. Soundness = validity + true premises.
- Inductive arguments are strong or weak, not valid; they make conclusions probable. Scientific generalisation and causal inference are inductive.
- In categorical logic, terms are distributed or undistributed; the middle term must be distributed at least once in a valid syllogism.
- Fallacies include affirming the consequent, ad hominem, straw man, false dilemma, begging the question, and post hoc ergo propter hoc.
- Scientific method involves hypothesis, prediction, observation or experiment, confirmation or falsification, and revision. Correlation alone does not establish causation.
Worked example
“All metals conduct electricity; copper is a metal; therefore copper conducts electricity.” This is a valid categorical syllogism in Barbara form. It is sound only if both premises are true. By contrast, “Copper conducts electricity; therefore all metals conduct electricity” is inductive and overgeneralised.
Traps
Do not call a valid argument true; truth belongs to propositions, validity to form. Do not treat a strong inductive conclusion as certain. Do not confuse necessary with sufficient conditions.