🧠 Logic & Critical Thinking

What you’ll learn

1. What Makes an ArgumentDefine an argument as premises supporting a conclusion and distinguish it from assertions and explanations.An argument offers premises as reasons for a conclusion, and the first skill is separating the two, aided by signal words. Arguments differ from mere assertions and from explanations, which account for something already accepted rather than arguing for a disputed claim.
2. Deductive vs. InductiveDistinguish deductive from inductive reasoning and the standards each is held to.Deductive reasoning aims for certainty (the conclusion follows necessarily), while inductive reasoning aims for probability by generalizing from evidence. Deductive arguments are valid or invalid; inductive ones are strong or weak, and their conclusions should be held in proportion to the evidence.
3. Validity and SoundnessExplain validity and soundness and why a valid argument can have a false conclusion.Validity means the conclusion must be true if the premises are, a matter of structure rather than fact, so a valid argument can still have a false conclusion from a false premise. A sound argument is both valid and has true premises, guaranteeing a true conclusion.
4. Argument Forms and Their TrapsRecognize valid conditional forms (modus ponens, modus tollens) and their invalid look-alikes.Modus ponens and modus tollens are always-valid conditional forms, while affirming the consequent and denying the antecedent are common invalid look-alikes. Validity depends on the argument's logical form, not its subject matter.
5. Fallacies of RelevanceIdentify fallacies of relevance and counter them by steel-manning.Fallacies of relevance — ad hominem, straw man, appeal to emotion, appeal to popularity, misused authority — persuade by introducing something beside the point. The remedy is to restate an opponent's view in its strongest form before responding.
6. Fallacies of PresumptionIdentify fallacies of presumption and judge when a suspected fallacy is a real error.Fallacies of presumption — false dilemma, slippery slope, circular reasoning, hasty generalization, equivocation — hide a faulty assumption. Naming a fallacy is a prompt to check whether the support holds, not an automatic refutation.
7. How the Mind Fools ItselfExplain cognitive biases and why process, not willpower, is the fix.Systematic biases such as confirmation bias, anchoring, the availability heuristic, and the Dunning-Kruger effect distort reasoning below awareness. Because willpower can't remove them, structured habits like seeking disconfirming evidence and outside views are the effective defense.
8. Weighing EvidenceEvaluate evidence: distinguish correlation from causation and interrogate claims and sources.Correlation does not imply causation, and a common cause or reverse causation may explain a link. A quick checklist — source, sample, causation, mechanism, replication — helps discount overselling headlines and weak evidence.
9. Reasoning with ProbabilityReason with probability: base rates and the conjunction fallacy.Untrained intuition mishandles probability, notably by neglecting base rates — why a highly accurate test for a rare disease still yields many false positives. The conjunction fallacy, judging a specific conjunction more likely than one of its parts, is another vivid violation of basic probability.
10. Thinking Well in PracticeCombine the skills into a routine of clarifying, checking, weighing, and calibrating belief.Good thinking is a repeatable loop: clarify the argument, classify it, check validity and premises, scan for fallacies and biases, weigh evidence and base rates, then hold belief in proportion to support. Steel-manning and willingness to update, aiming at calibration rather than false certainty, complete the practice.

Questions this course answers

Grounded in trusted sources

• Patrick J. Hurley & Lori Watson, 'A Concise Introduction to Logic' (Cengage)
• Aristotle, 'Prior Analytics' and 'Sophistical Refutations'
• Daniel Kahneman, 'Thinking, Fast and Slow' (Farrar, Straus and Giroux, 2011)
• Amos Tversky & Daniel Kahneman, 'Judgment under Uncertainty: Heuristics and Biases', Science (1974)
• Carl Sagan, 'The Demon-Haunted World: Science as a Candle in the Dark' (1995)
• Internet Encyclopedia of Philosophy and Stanford Encyclopedia of Philosophy — entries on Fallacies, Validity, and Argument

Every Wunder lesson is built from real, reputable sources — never invented.

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