List of fallacies Study Guide

📖 Core Concepts Fallacy – use of invalid or faulty reasoning; the argument is unsound (premises not well‑grounded, conclusion unproven). Formal fallacy – error in the logical form (structure) of an argument; always a non‑sequitur. Informal fallacy – error in the content of an argument (premises, relevance, evidence). Non‑sequitur – conclusion does not follow from the premises. Premise vs. conclusion – a sound argument requires premises that are true (or well‑supported) and a conclusion that logically follows. 📌 Must Remember Every formal fallacy is a non‑sequitur. Informal fallacies are far more common than formal ones. Fallacy fallacy: assuming that because an argument is fallacious, its conclusion must be false. Base‑rate fallacy – ignore prior probabilities; conjunction fallacy – think a conjunction is more probable than a single event. Affirming the consequent: \(P \rightarrow Q,\; Q\) → invalidly infer \(P\). Denying the antecedent: \(P \rightarrow Q,\; \neg P\) → invalidly infer \(\neg Q\). Undistributed middle: the middle term is not distributed in either premise → invalid syllogism. Begging the question / circular reasoning – premise already assumes the conclusion. Hasty generalization – draw a broad claim from a tiny/biased sample. Cherry‑picking / survivorship bias – select evidence that supports a claim while ignoring contrary data. Post‑hoc ergo propter hoc – “X happened before Y, therefore X caused Y.” Cum‑hoc ergo propter hoc – “X and Y covary, therefore X causes Y.” Ad hominem – attack the person, not the argument. Straw man – refute a distorted version of the opponent’s claim. Appeal to authority – claim truth because an expert says so (without supporting evidence). Appeal to emotion – manipulate feelings (fear, pity, flattery, ridicule) instead of providing reasons. Appeal to popularity (bandwagon) – “many people believe it, so it must be true.” 🔄 Key Processes Identify the type of fallacy Check structure → possible formal fallacy (e.g., affirming consequent). Check content/relevance → possible informal fallacy (e.g., ad hominem). Test the logical form Write premises in symbolic form (if possible). Verify that the conclusion follows via valid inference rules. Evaluate evidence Are premises well‑grounded? Look for omitted counter‑evidence (cherry‑picking) or small samples (hasty generalization). Search for hidden assumptions Does the argument presuppose something unproved? (loaded label, many‑question). Apply the “Fallacy Checklist” Formal? → non‑sequitur, undistributed middle, illicit major/minor, etc. Informal? → improper premise, faulty generalization, questionable cause, relevance, ad hominem, appeal, etc. 🔍 Key Comparisons Affirming the consequent vs. denying the antecedent Affirming the consequent: \(P \rightarrow Q,\; Q\) → wrongly infer \(P\). Denying the antecedent: \(P \rightarrow Q,\; \neg P\) → wrongly infer \(\neg Q\). Post‑hoc vs. cum‑hoc Post‑hoc: temporal order → causation. Cum‑hoc: mere correlation → causation. Ad hominem attack vs. circumstantial ad hominem Attack: insults the person’s character. Circumstantial: rejects claim because of the person’s interests. Straw man vs. red herring Straw man: misrepresents the opponent’s argument. Red herring: introduces an irrelevant issue to distract. Appeal to authority vs. appeal to achievement Authority: cites prestige. Achievement: cites personal successes unrelated to the claim’s truth. ⚠️ Common Misunderstandings “All fallacies are false arguments.” → A fallacy makes an argument unsound; the conclusion may still be true by coincidence. Confusing “correlation” with “causation.” → Leads to post‑hoc or cum‑hoc errors. Treating a single anecdote as proof. → Argument from anecdote is a weak informal fallacy. Assuming a complex conjunction is more likely than a single event. → Conjunction fallacy. Believing that because a speaker is an expert, every claim they make is true. → Appeal to authority fallacy. 🧠 Mental Models / Intuition “Form follows function” → If the form (logical structure) doesn’t match the function (intended inference), a formal fallacy is present. “Evidence ≠ Confirmation” – Evidence must support a claim; cherry‑picking tricks you into thinking it does. “Cause ≠ Correlation” – Visualize two lines moving together; ask, “Is there a mechanism?” before assuming causality. “Person ≠ Argument” – Separate the messenger from the message; if you’re attacking the messenger, you’ve slipped into ad hominem. 🚩 Exceptions & Edge Cases Fallacy of the undistributed middle can sometimes be legitimate if the middle term is actually distributed (e.g., “All mammals are animals; all dogs are mammals → all dogs are animals” is valid). Appeal to authority is not a fallacy when the authority is relevant and the claim is within their expertise and supported by evidence. Bare assertion (ipse dixit) may be acceptable in definitional contexts where a premise is a convention, not a factual claim. 📍 When to Use Which Formal analysis → use when the argument’s logical form is explicit (syllogisms, conditional statements). Informal analysis → use when the argument relies on examples, anecdotes, emotional language, or relevance attacks. Statistical scrutiny → apply to arguments invoking probabilities, base rates, or observational data (watch for base‑rate, conjunction, gambler’s fallacy). Source evaluation → apply when an appeal to authority or accomplishment appears; check expertise and relevance. 👀 Patterns to Recognize “X happened before Y, therefore X caused Y.” → spot post‑hoc. “Most people think… therefore it’s true.” → spot bandwagon. “Because this expert says so…” with no supporting data → spot appeal to authority. “If A then B; B is true, so A must be true.” → spot affirming the consequent. “All A are B; All C are B; therefore All A are C.” → spot undistributed middle / four‑term fallacy. “You’re just saying that because you’re rich/poor.” → spot appeal to wealth/poverty. 🗂️ Exam Traps Distractor: “The argument is sound because the premises are true.” → Wrong if the conclusion doesn’t follow (formal fallacy). Distractor: “Correlation proves causation.” → Picks cum‑hoc; the correct answer should note lack of causal mechanism. Distractor: “An expert’s statement is automatically correct.” → Appeals to authority; need to assess relevance and evidence. Distractor: “Since the speaker used a harsh tone, the argument is invalid.” → Confuses tone policing (ad hominem) with logical invalidity. Distractor: “Because the claim is popular, it must be true.” → Bandwagon trap. Distractor: “The argument is a fallacy because the conclusion is false.” → Misunderstanding; a true conclusion can still be reached via a fallacy. --- Use this guide to scan each argument quickly: identify the logical form, check the evidence, watch for hidden assumptions, and match the pattern to a named fallacy.