A logical fallacy is a mistake in reasoning that makes an argument weaker than it looks. The speaker gives reasons, but those reasons do not really support the conclusion.
Here is one you may have heard: “If you really cared about the planet, you’d never fly.” It sounds convincing, yet it ignores every other way to help. Here we’ll explain 15 fallacies, each with a plain example and a polite reply.
- What a logical fallacy is and how to pronounce fallacy
- Formal and informal fallacies
- 15 common logical fallacies in three simple groups
- How to spot a fallacy and reply politely
- How to avoid fallacies in your own essays, with a practice quiz
What Is a Logical Fallacy?
Quick Navigation
Every argument has two parts: a claim (what the speaker wants you to believe) and reasons (why you should believe it). A good argument has a strong link between them.
A fallacy breaks that link. The facts might even be true, but they do not prove the claim. This is why fallacies can be so persuasive: they often sound reasonable at first.
⬇ relevant link
Claim: “The drug probably works.”
⬇ broken link
Claim: “The drug works.”
How to pronounce fallacy
| Word | Sounds like | IPA | Part of speech |
|---|---|---|---|
| Fallacy | FAL-uh-see | /ˈfæl.ə.si/ | Noun |
| Fallacies | FAL-uh-seez | /ˈfæl.ə.siz/ | Plural noun |
| Fallacious | fuh-LAY-shus | /fəˈleɪ.ʃəs/ | Adjective |
Useful patterns: commit a fallacy, a fallacious argument, this argument relies on a fallacy, a common fallacy. See more on our fallacy dictionary page.
Formal vs Informal Fallacies
| Type | What goes wrong | Example |
|---|---|---|
| Formal fallacy | The structure of the argument is broken | “If it rains, the street gets wet. The street is wet, so it rained.” (Someone may have washed it.) |
| Informal fallacy | The content is weak, irrelevant or misleading | “You can’t trust his idea; he’s only 19.” |
Most fallacies you meet in daily life are informal. The 15 below are all informal fallacies, grouped into three families.
15 Common Logical Fallacies
Group 1: Attacking or avoiding the real argument
| Fallacy | What happens | Example |
|---|---|---|
| Ad hominem | Attacks the person, not the argument | “Why listen to her climate plan? She drives a big car.” |
| Straw man | Twists an argument into a weaker one, then attacks it | “You want less homework? So you think students shouldn’t learn anything.” |
| Red herring | Changes the subject to distract | “Yes, our prices went up, but look at our beautiful new logo.” |
| Tu quoque (whataboutism) | Answers criticism with “you do it too” | “You say I eat too much sugar, but you drink cola every day.” |
Group 2: Weak or unfair evidence
| Fallacy | What happens | Example |
|---|---|---|
| Hasty generalization | A big conclusion from a few cases | “Two of my neighbors are rude, so people in this city are rude.” |
| Appeal to false authority | Trusts someone who is not an expert on the topic | “A famous footballer says this diet works, so it must.” |
| Bandwagon | Something is right because many people believe it | “Everyone is buying this phone, so it must be the best.” |
| Anecdotal evidence | One personal story replaces real data | “My grandfather smoked and lived to 95, so smoking isn’t harmful.” |
| Cherry picking | Chooses only the facts that help | Showing one good month of sales and hiding a bad year |
Group 3: Faulty cause, choice or logic
| Fallacy | What happens | Example |
|---|---|---|
| Slippery slope | One small step will lead to disaster, with no evidence | “If we allow phones at lunch, soon nobody will study.” |
| False cause | Because B came after A, A caused B | “I wore my lucky socks and we won, so the socks helped.” |
| False dilemma | Only two choices when there are more | “You either support this law or you don’t care about children.” |
| Circular reasoning | The conclusion is used as the reason | “This book is reliable because the book says so.” |
| Appeal to ignorance | Something is true because nobody has proved it false | “No one has proved ghosts don’t exist, so they’re real.” |
| Appeal to emotion | Feelings replace evidence | “Think of the poor animals. You must agree with me.” |
Latin names you may see (tap a card)
Ad hominemTap to reveal
Tu quoqueTap to reveal
Post hoc ergo propter hocTap to reveal
Non sequiturTap to reveal
How to Spot a Logical Fallacy
When you read or hear an argument, ask these five questions.
- Is the speaker talking about the argument or the person? If the person, think ad hominem.
- Is this what the other side really said? If not, think straw man.
- Does this answer the question? If not, think red herring.
- Is the evidence enough? One story, one expert or one popular opinion is rarely enough.
- Does each step really lead to the next? Look for missing links, false causes and only-two-choices thinking.
Check your answer
How to Reply Politely
Naming a fallacy out loud (“That’s a straw man!”) can sound rude. In discussions, meetings and speaking exams, these softer phrases work better.
| Situation | Polite reply |
|---|---|
| Someone attacks you, not your idea | “Let’s focus on the idea itself. What do you think of the plan?” |
| Someone twists your words | “That’s not quite what I said. My point is that…” |
| Someone changes the subject | “That’s a fair point, but I’d like to come back to the main question.” |
| Someone predicts a disaster | “Is there evidence that one step will really lead to the next?” |
| Someone offers only two options | “I think there might be a third option here.” |
| Someone uses one example | “That’s one case. Do we know if it’s typical?” |
You can practice these in our C2 lesson on rebuttal techniques and the C1 lesson on conceding and refuting a counter-argument.
How to Avoid Fallacies in Your Own Writing
- Use relevant evidence. Facts, studies and expert opinions from the right field.
- Describe the other side fairly. Present the strongest version of the opposing view, then respond to it.
- Be careful with absolute words. Always, never, everyone and nobody are rarely true.
- Hedge your predictions. Write “This could lead to…” rather than “This will definitely cause…”.
- Check each step. Read your argument and ask, “Does this really follow?”
For more on strong arguments, see the anatomy of a strong argument and our lesson on ethos, pathos and logos.
Common Mistakes Learners Make
- Calling every weak argument a fallacy. Some arguments are simply wrong about the facts. A fallacy is a problem with the reasoning.
- Thinking a fallacy proves the opposite. A badly argued claim can still be true.
- **Mixing up the two meanings of fallacy.** In daily English, “a common fallacy” often means a popular false belief.
- Spelling: fallacy has a double l; the plural is fallacies.
Practice: Test Your Understanding
Part A. Name the fallacy: ad hominem, bandwagon, false dilemma, hasty generalization, slippery slope, red herring.
- “You’re either with us or against us.”
- “If we let one student retake the test, every student will want to, and exams will become meaningless.”
- “The film must be great. It’s number one at the box office.”
- “I met two lazy teenagers yesterday. Young people today don’t want to work.”
- “Why should we listen to a doctor who can’t even keep her own garden tidy?”
- “Is the bridge safe? Well, our town has won three awards for its parks.”
Show answers for Part A
- False dilemma – there are more than two positions.
- Slippery slope – no evidence for the chain of events.
- Bandwagon – popularity does not prove quality.
- Hasty generalization – two people are not enough.
- Ad hominem – her garden has nothing to do with her medical advice.
- Red herring – the parks do not answer the question about the bridge.
Part B. Rewrite each fallacy as a fair argument.
- “Everyone is learning Spanish, so you should too.”
- “If you don’t go to university, you’ll never get a good job.”
Show sample answers for Part B
- “Spanish is spoken by millions of people, so it could be useful for travel and work.”
- “A degree can help in many careers, but there are other routes, such as apprenticeships.”
Part C (writing). Find an ad or a social media post that tries to persuade you. Write three sentences: what it claims, what fallacy (if any) it uses, and how it could be argued more fairly. Check your writing with our AI Writing Feedback tool.
Key Takeaways
- A logical fallacy is a mistake in reasoning, not just a false fact.
- Most everyday fallacies are informal: they use weak, irrelevant or unfair content.
- Three families: attacking or avoiding the argument, weak evidence, and faulty cause or choice.
- Reply politely: focus on the idea, correct the record, and ask for evidence.
- In your own writing, use relevant evidence, describe the other side fairly and hedge your predictions.
Explore each fallacy in more depth, starting with ad hominem, the straw man fallacy and the slippery slope fallacy.
Frequently Asked Questions
What is a logical fallacy in simple words?
A logical fallacy is a mistake in reasoning. The reasons someone gives do not really support their conclusion, even if the argument sounds convincing at first.
What are the most common logical fallacies?
Some of the most common are ad hominem, straw man, red herring, slippery slope, hasty generalization, false dilemma, bandwagon, appeal to authority, false cause and circular reasoning.
What is the difference between a formal and an informal fallacy?
A formal fallacy is a mistake in the structure of an argument, so the conclusion does not follow. An informal fallacy is a mistake in the content, such as weak evidence or an irrelevant point. Most everyday fallacies are informal.
Can an argument with a fallacy still have a true conclusion?
Yes. A fallacy shows that the reasoning is weak, not that the conclusion is false. Saying a claim must be wrong because the argument for it is fallacious is itself a mistake, sometimes called the fallacy fallacy.
How do I avoid logical fallacies in an essay?
Support each claim with relevant evidence, describe opposing views fairly, avoid words like “always” and “never” unless they are true, and check that each step of your argument really leads to the next.
What does “fallacy” mean in everyday English?
In everyday English, a fallacy can also mean a common false belief, as in “It’s a fallacy that money always brings happiness.” In logic and debate, it means a mistake in reasoning.
Related Articles
- Logical Fallacies: 15 Common Types with Examples - October 6, 2026
- Ethos, Pathos and Logos: The 3 Persuasive Appeals with Examples - October 6, 2026
- Paradox: Meaning, Types and Examples in Literature and Life - October 5, 2026
