Logic & Fallacy Quiz
Identify whether an argument is deductive, inductive, or abductive — and name the logical fallacy when one is present. 45 problems across three tiers: Foundation covers the most common fallacies (ad hominem, straw man, false dilemma, slippery slope, appeal to authority, bandwagon, hasty generalization, appeal to ignorance) and basic argument types. Intermediate adds subtle informal fallacies (post hoc, tu quoque, anecdotal evidence, appeal to nature, poisoning the well, circular reasoning, relative privation). Advanced covers formal fallacies (affirming the consequent, denying the antecedent, modus tollens), validity vs. soundness, equivocation, and abductive reasoning.
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How to Play Argument Types
Read the Argument
Each question presents an argument — it may be a formal multi-premise syllogism (like 'All mammals breathe air. Dolphins are mammals. ∴ Dolphins breathe air.') or an informal everyday argument (like 'You can't trust Maria's opinion — she's overweight.'). The '∴' symbol means 'therefore' and marks the conclusion.
Check the Category Badge
The colored badge tells you what you're being asked: IDENTIFY TYPE means pick which kind of reasoning this is. FALLACY means name the specific logical error. FORMAL LOGIC means classify the argument structure using formal logic terms. EVALUATE means assess whether the argument is valid, sound, or strong.
Choose Your Level
Foundation covers the classic fallacies taught in critical thinking and rhetoric courses. Intermediate adds subtler informal fallacies that require more nuance to recognize — like post hoc vs. false cause, or tu quoque vs. ad hominem. Advanced introduces formal logic notation, the validity/soundness distinction, and the difference between formal and informal fallacies.
Learn from the Explanation
After every answer, a detailed explanation appears showing exactly why the correct answer is right — including why the other options are wrong. For fallacies, the explanation names the Latin term, gives the structure of the error, and provides the key insight for recognizing it in the future.
Key Features
45 Problems Across 3 Tiers
Foundation (15): Distinguish deductive, inductive, and abductive reasoning from clear examples; identify the most widely taught fallacies — ad hominem, straw man, false dilemma, slippery slope, bandwagon, appeal to tradition, hasty generalization, and appeal to ignorance. Intermediate (15): Name subtler informal fallacies — anecdotal evidence, tu quoque, false cause (cum hoc), post hoc ergo propter hoc, appeal to nature, poisoning the well, circular reasoning, circumstantial ad hominem, relative privation, and appeal to consequences. Advanced (15): Formal fallacies with logical notation (affirming the consequent, denying the antecedent, modus tollens), validity vs. soundness distinctions, equivocation, non sequitur, red herring, and abductive inference-to-best-explanation.
Formal Argument Display
Multi-premise arguments are shown in structured form with premises listed above a dividing line and the conclusion introduced with '∴' (therefore) in gold. This mirrors how arguments are presented in logic textbooks and philosophy courses, making the structure immediately readable.
4 Question Modes
IDENTIFY TYPE (amber): What kind of reasoning is this — deductive, inductive, abductive, or analogical? FALLACY (rose): What is the name of the fallacy in this argument? FORMAL LOGIC (purple): Classify the argument form — is it modus ponens, modus tollens, affirming the consequent, or denying the antecedent? EVALUATE (sky): Is this argument valid, sound, strong, or weak?
Dark Indigo Philosophical Theme
The game uses a deep slate/indigo color scheme with gold accents — evoking the atmosphere of a philosophy seminar or logic classroom. The lobby displays the classic Socrates syllogism alongside a visual summary of the three argument types, immediately orienting new players.
Frequently Asked Questions
What's the difference between deductive and inductive reasoning?
Deductive reasoning guarantees the conclusion IF the premises are true. The classic example: 'All humans are mortal. Socrates is human. Therefore, Socrates is mortal.' If the premises are true, the conclusion cannot be false — it's logically necessary. Inductive reasoning supports a probable conclusion from evidence, but cannot guarantee it. Example: 'Every swan I've seen is white. Therefore, all swans are probably white.' (False! Black swans exist.) Inductive arguments range from weak (few cases) to strong (many diverse cases), but never achieve logical certainty.
What is abductive reasoning?
Abductive reasoning — also called 'inference to the best explanation' — picks the most plausible explanation for a set of observations. It's the reasoning of detectives (Sherlock Holmes), doctors (diagnosing from symptoms), and scientists (forming hypotheses). Example: 'The patient has a fever, rash, and joint pain. The best explanation is Lyme disease.' Abductive conclusions are tentative — better evidence can change the conclusion. It's neither deductive (no guarantee) nor purely inductive (not a generalization from frequency).
What is the difference between a valid and a sound argument?
A VALID argument has a correct logical form — if the premises were true, the conclusion would have to be true. 'All unicorns can fly. Sparkle is a unicorn. Therefore, Sparkle can fly.' is valid (the form is correct) but UNSOUND (the premises are false). A SOUND argument is valid AND has all true premises. A sound argument is guaranteed to have a true conclusion. Validity is about structure; soundness is about structure + truth.
What's the difference between formal and informal fallacies?
FORMAL fallacies are errors in the logical structure itself, independent of content. Affirming the Consequent (P→Q, Q, ∴ P) is formal — it's always invalid regardless of what P and Q say. INFORMAL fallacies are errors in the content, context, or delivery of an argument, not its logical form. Ad Hominem is informal — the logical form might be fine, but the content (attacking the person) undermines the argument's relevance. Most named fallacies (hasty generalization, straw man, slippery slope) are informal.
What is the difference between Ad Hominem and Straw Man?
Ad Hominem attacks the PERSON making the argument: 'You can't trust her nutrition advice — she's overweight.' The argument itself is never addressed. Straw Man distorts the ARGUMENT itself into a weaker version: 'My opponent wants to reduce military spending' → 'My opponent wants America to be defenseless.' The real argument is misrepresented. Both are irrelevant-to-the-actual-argument fallacies, but Ad Hominem attacks the source and Straw Man attacks a fictional version of the claim.
How does scoring work?
Correct answers earn 10 pts (Foundation), 15 pts (Intermediate), or 20 pts (Advanced). Consecutive correct answers add a 5-point streak bonus per answer after the first. A wrong answer resets the streak to zero. Your best all-time score persists across sessions.