How to Spot Logical Fallacies

A logical fallacy is a flaw in reasoning that makes an argument invalid or weak. Spotting fallacies—in others' arguments and your own—is a key part of critical thinking. Common types include straw man (misrepresenting a view), ad hominem (attacking the person), circular reasoning (assuming what you're trying to prove), and false dilemma (presenting only two options). Below: the main fallacies, how to spot them in your own writing, and how argument mapping and a logic linter can catch them.

Common logical fallacies

• Straw man — Misrepresenting someone's view so it's easier to attack. ("You think we should do X." "No, I said we should consider Y.")
• Ad hominem — Attacking the person instead of the argument. ("You're wrong because you're biased.")
• Circular reasoning — Using the conclusion (or something that assumes it) as a premise. ("The Bible is true because it says it's true.")
• Appeal to authority — Treating "an expert said so" as sufficient proof without examining the reasoning.
• False dilemma — Presenting two options as the only ones when more exist. ("Either you're with us or against us.")
• Slippery slope — Claiming one step will inevitably lead to extreme outcomes without showing the causal chain.
• Hasty generalization — Drawing a broad conclusion from too few or unrepresentative examples.

None of these means the conclusion is false—they mean the argument for it is weak. You can have a true conclusion and a bad argument. The point of spotting fallacies is to improve the argument or to see when someone hasn't given you a good reason to believe them. In practice, the same argument can commit more than one fallacy—for example, a straw man plus an ad hominem. Map the argument first; then name each move. That way you're not just labeling but improving the structure. If you want to practice on real arguments, use the Argument Cartographer and run the linter; it will flag circular reasoning and contradictions automatically.

How to spot fallacies in your own writing

1. Map the argument — Use argument mapping to lay out premises and conclusions. Circular reasoning and missing support become visible.
2. Use a logic linter — The Argument Cartographer includes a logic linter that flags circular reasoning, contradictions, and unsupported claims in your maps.
3. Ask "so what?" — For each premise, ask: does this actually support the conclusion? Or am I assuming what I'm trying to prove?
4. Consider objections — Would a critic say you're attacking a straw man or ignoring alternatives? Add objections to your map and respond to them.

The linter won't catch everything—for example, it won't tell you that your premise is false, only that the structure is broken. But structure is where many arguments fail. Fix that first, then worry about evidence. Some fallacies are about relevance (ad hominem, appeal to authority); others are about form (circular reasoning, false dilemma). Learning to name them helps you both criticize others' arguments and tighten your own. The list in this post isn't exhaustive—there are many more named fallacies—but these are the ones you'll see most often in everyday argument. Once you can spot them, you can add more (e.g. begging the question, red herring) from a logic or critical thinking resource. The Argument Cartographer linter focuses on structural issues (circularity, contradiction, unsupported claims); the rest you learn by practice and by reading about fallacies. If you're not sure where to start, pick one fallacy from the list above and look for it in the next op-ed or thread you read. Where to go from here. Build a map in the Cartographer and run the linter; add an objection to your map and respond to it. For more exercises, see Critical thinking exercises you can do today. Are fallacies always intentional? No. People often commit straw man or false dilemma without realizing it. The point of learning fallacies isn't to accuse others of cheating—it's to see when an argument is weak and to fix your own. What if my argument has a fallacy? Then the argument doesn't support the conclusion the way you thought. You might need a new premise, a different structure, or to give up that conclusion. Mapping and the linter help you see that.

Practice on schrodingers.cat

Build argument maps in the Cartographer, run the linter, and share maps to the forum for feedback. Combine this with learning paths and Socratic dialogues to strengthen both your reasoning and your ability to spot fallacies. If you want more exercises, see Critical thinking exercises you can do today. The linter won't catch every fallacy (e.g. it won't flag a straw man by name), but it will catch structural problems that often go hand in hand with weak argumentation. Fix those first, then read through your map and ask whether any premise is a misrepresentation or an irrelevant attack. Over time you'll start to spot fallacies in real time when you read or listen—and you'll catch them in your own drafts before you publish or send. That's the habit we're building. You can also use the linter on someone else's argument: map their reasoning, run the linter, and see where the structure fails. It's a fair way to criticize an argument without attacking the person—you're pointing to gaps and fallacies in the reasoning itself. The same fallacies show up in politics, advertising, and everyday conversation—learning to name them here will help you everywhere. Start with one fallacy—e.g. straw man or circular reasoning—and look for it in the next thing you read; then add another. Building the habit matters more than memorizing the full list. Share your map to the forum for feedback and see how others spot fallacies. Combining mapping with learning paths and Socratic dialogue gives you the full set of tools for clear reasoning.

Build an argument map →

Key takeaway: Fallacies like straw man, ad hominem, and circular reasoning weaken arguments. Map your argument and run the linter to find and fix them.