Logical Fallacies and Errors

Types of Appeals

  • Appeal to Tradition / Common Practice

    • Definition: Argues that something is valid simply because it has been traditionally done.
    • Example: "We've always used paper ballots - why change it now?"

  • Bandwagon

    • Definition: Claims something is true or good because it is popular or widely accepted.
    • Example: "Everyone's buying this phone, so it must be the best."

  • Appeal to Novelty

    • Definition: Assumes something is superior merely because it is new.
    • Example: "This app just launched - it must be better than the old one."

  • Appeal to Flattery

    • Definition: Utilizes compliments to gain support rather than logical reasoning.
    • Example: "You're so smart, you'll definitely agree with me on this."

Ad Hominem Arguments

  • Ad Hominem - Tu Quoque

    • Definition: Responding to criticism by pointing to the accuser's hypocrisy.
    • Example: "You smoke too - so don't tell me it's bad."

  • Ad Hominem - Circumstantial

    • Definition: Attacks the individual's circumstances rather than their argument.
    • Example: "You only support higher taxes because you're a student."

  • Ad Feminam

    • Definition: Targets someone based on gender instead of addressing the argument.
    • Example: "She's just emotional - ignore what she's saying."

Emotional & Distraction Fallacies

  • Appeal to Spite

    • Definition: Dismisses an argument due to personal resentment.
    • Example: "Don't vote for him - he got that promotion you deserved."

  • Appeal to Fear

    • Definition: Uses fear as a means of persuasion instead of rational argument.
    • Example: "If you don't buy this security system, your house could get robbed."

  • Appeal to Pity

    • Definition: Leverages sympathy instead of sound reasoning.
    • Example: "I should get an A - I worked so hard and my dog died."

  • Guilt by Association

    • Definition: Discredits someone based on their associations.
    • Example: "He hangs out with criminals, so he must be one too."

  • Poisoning the Well

    • Definition: Discredits someone before they have a chance to speak.
    • Example: "Before he talks, remember he's a liar."

  • Honor by Association

    • Definition: Occurs when accepting an idea due to its supporters.
    • Example: "Einstein liked this theory, so it must be true."

Logic Errors

  • Sunk Cost Fallacy

    • Definition: Continuing an endeavor due to prior investments.
    • Example: "I've spent 2 hours on this movie - I can't stop now."

  • Gambler's Fallacy

    • Definition: Belief that past random events affect future random events.
    • Example: "I've lost 5 times - next one has to be a win!"

  • Texas Sharpshooter

    • Definition: Selecting data that supports an argument while ignoring other data.
    • Example: "This town has fewer robberies, so it must be safer - ignores murder rates."

  • Cherry Picking

    • Definition: Using only evidence that supports your argument while ignoring contradictory information.
    • Example: "Look at this one study that supports my diet - ignores 20 others."

  • Misleading Vividness

    • Definition: Using dramatic events to form broad conclusions.
    • Example: "I saw one shark attack - swimming is always dangerous!"

Burden of Proof & Circular Reasoning

  • Burden of Proof / Appeal to Ignorance

    • Definition: Claims something is true without evidence proving it false.
    • Example: "No one's proved aliens don't exist, so they must exist."

  • Begging the Question / Circular Reasoning

    • Definition: Uses the conclusion as a premise of the argument.
    • Example: "He's honest because he always tells the truth."

Cause & Effect Errors

  • Confusing Cause and Effect

    • Definition: Errors in determining the direction of causation between events.
    • Example: "People who sleep more are happier - so sleeping makes you happy." (May be the case that happy people sleep more).

  • Post Hoc Ergo Propter Hoc

    • Definition: Concludes that one event caused another merely because it occurred earlier.
    • Example: "I wore red and won my game - red is lucky!"

  • Ignoring a Common Cause

    • Definition: Misallocates blame to one cause rather than recognizing a shared contributing factor.
    • Example: "Kids who play violent games are angry - ignores family issues causing both."

Sample & Definition Issues

  • Biased Sample

    • Definition: Uses an unrepresentative sample to make conclusions.
    • Example: "90% of my friends hate school - so most students must." (Your friends may not represent the entire student body).

  • Hasty Generalization

    • Definition: Draws broad conclusions based on insufficient evidence.
    • Example: "One bad driver from New York - New Yorkers are terrible drivers."

  • No True Scotsman

    • Definition: Modifies the definition to protect a claim from counterexamples.
    • Example: "No Scotsman puts sugar on porridge."
      "My uncle is Scottish and he does."
    • "Well, no true Scotsman would."

Other Logic Slips

  • Equivocation (Ambiguity)

    • Definition: Utilizing words with multiple meanings in misleading ways.
    • Example: "Feathers are light. Light things aren't dark. So feathers aren't dark."

  • Slippery Slope

    • Definition: Asserts that a minor action will lead to extreme and dire consequences.
    • Example: "If we allow phones in class, soon no one will learn anything."

  • Middle Ground

    • Definition: Assumes that the middle position between two extremes is always the correct one.
    • Example: "One person says the sky is blue, the other says it's red - so it must be purple."

  • Two Wrongs Don't Make a Right

    • Definition: Justifies inappropriate actions by pointing to similar actions by others.
    • Example: "He cheated on me, so I cheated too."