Logical Fallacies

Arguments & Evidence

Ad Hominem

• Attacking the person^ⓘ instead of addressing the argument
• Example: "You can't trust his views on nutrition—he's overweight"
• Why it's wrong: The validity of an argument is independent of who makes it

Strawman

• Misrepresenting someone's argument^ⓘ to make it easier to attack
• Example: "You want better public transport? So you want to ban all cars?"
• Why it's wrong: You're not engaging with what they actually said

Appeal to Authority

• Accepting something as true because an expert said it^ⓘ
• Example: "This famous physicist says homeopathy works"
• Why it's wrong: Expertise in one field doesn't transfer to others; always ask for evidence

Appeal to Nature

• Assuming natural = good/healthy^ⓘ
• Example: "It's natural, so it must be safe"
• Why it's wrong: Arsenic, poison ivy, and earthquakes are all natural

Burden of Proof

• Demanding others disprove your claim^ⓘ
• Example: "You can't prove ghosts don't exist, so they must be real"
• Why it's wrong: The person making the claim must provide evidence

Cause & Effect

Post Hoc

• Assuming correlation means causation^ⓘ
• Example: "I wore my lucky socks and won—the socks caused it"
• Also known as: Post hoc ergo propter hoc ("after this, therefore because of this")

False Cause

• Finding patterns in noise^ⓘ
• Example: "Ice cream sales and drowning both increase in summer—ice cream must cause drowning"
• Why it's wrong: Both are caused by a third factor (hot weather)

Slippery Slope

• Claiming one step inevitably leads to extreme consequences^ⓘ
• Example: "If we allow this small change, society will collapse"
• When valid: Only if there's actual evidence for the chain of causation

Faulty Logic

False Dilemma

• Presenting only two options when more exist^ⓘ
• Example: "You're either with us or against us"
• Why it's wrong: Most situations have multiple options or nuanced positions

Circular Reasoning

• Using your conclusion as a premise^ⓘ
• Example: "The Bible is true because it says so in the Bible"
• Also known as: Begging the question

Hasty Generalization

• Drawing broad conclusions from limited examples^ⓘ
• Example: "I met two rude French people, so French people are rude"
• Why it's wrong: Small or biased samples don't represent the whole

No True Scotsman

• Moving the goalposts to protect a generalization^ⓘ
• Example: "No real fan would criticize the show" (redefining 'real fan')
• Why it's wrong: You can't change your definition after the fact

Emotional Tricks

Appeal to Emotion

• Using feelings instead of evidence^ⓘ
• Example: "Think of the children!" (without relevant evidence)
• Not always wrong: Emotions are valid in ethics—but shouldn't replace facts

Bandwagon

• Something is true/good because many people believe/do it^ⓘ
• Example: "Everyone's buying it, so it must be good"
• Why it's wrong: Millions once believed the Earth was flat

Appeal to Tradition

• It's right because we've always done it this way^ⓘ
• Example: "We've always done it this way"
• Why it's wrong: Longevity doesn't prove something is correct or optimal

Sunk Cost Fallacy

• Continuing because of past investment^ⓘ
• Example: "I've already watched three hours of this terrible movie, I might as well finish"
• Why it's wrong: Past costs are gone—only future costs and benefits matter

How to Spot Fallacies

• Pause before reacting — Strong emotions often signal manipulation
• Ask for evidence — What's the actual data supporting this claim?
• Consider alternatives — Are there other explanations or options?
• Check the logic — Does the conclusion actually follow from the premises?
• Look for the motive — Who benefits from you believing this?