Card 4.2.1 · Root IV — Logic
Fallacies
When is a bad-looking argument actually bad?
A fallacy is a pattern of reasoning that appears to support its conclusion but does not.
On this card
Where it sits
Under 4.2 Informal logic. Borders 4.2.2 Argumentation theory, 2.6 Rationality.
The catalogue, with legitimate versions
| Named fallacy | The bad version | The legitimate version |
|---|---|---|
| Ad hominem | Rejecting a claim because of who said it | Questioning testimony where the speaker's reliability or interest is genuinely at issue |
| Appeal to authority | Citing authority on a matter outside their competence, or where experts disagree | Deferring to genuine expertise in its own domain — which is how most knowledge works |
| Slippery slope | Asserting a chain of consequences with no mechanism | Arguing a chain where each step has demonstrable precedent or pressure |
| Appeal to emotion | Substituting feeling for evidence | Directing attention to stakes that are genuinely morally relevant |
| Appeal to nature | Inferring good from natural | Arguing from biological function where function is the actual question |
| Straw man | Attacking a version nobody holds | Attacking a version someone does hold, however weak |
| False dilemma | Presenting two options when more exist | Presenting two options when the alternatives really are exhausted |
| Circular reasoning | Assuming the conclusion in a premise | Coherent systems where mutual support is the point, per 2.3.1 |
| Appeal to ignorance | Absence of evidence taken as evidence of absence | Absence of evidence where evidence would be expected if the claim were true |
| Composition and division | Inferring from parts to whole or the reverse | Where the property genuinely does transfer, as with mass |
| Post hoc | Inferring cause from sequence | Where sequence is combined with mechanism and controls |
| Genetic fallacy | Judging a claim by its origin | Where origin bears on reliability, as with a fabricated source |
Key figures
| Figure | Dates | Tradition | Contribution |
|---|---|---|---|
| Aristotle | 384–322 BCE | Greek | Sophistical Refutations; the earliest surviving catalogue |
| The Nyaya school | c. 2nd c. CE onward | Indian | Hetvabhasa: five classes of defective reason |
| Dignāga | c. 480–540 | Indian Buddhist | The wheel of reasons; a test for genuine support |
| C. L. Hamblin | 1922–1985 | Analytic | Demonstrated the standard treatment was incoherent |
Connections
→ 4.2 · ↔ 4.2.2, 2.2.4, 2.7.1, 2.6 · ◇ informal logic, argumentation schemes · ○ Axial Age; Classical; Modern; Table 3
→ narrower questions · ↔ questions it borders · ◇ the positions, mapped in Part III of the book · ○ the eras and comparison tables (Parts IV and V)
The full card is in the book
In The Coordinates of Thought this card goes on to a worked example that sets the answers against one case, and to where the question touches daily life — page 192.
On Coordinates of Thought
Conversations about this question in Fallacies & paradoxes:
- Slippery-slope arguments in medicine are usually predictions, not fallacies 6 replies
- I banned fallacy names from my debate team for a month. Here’s what happened 5 replies
- After reading Hamblin, should I still teach my prison class the list of fallacies? 5 replies
- ‘With us or against us’ sounds like logic. Is it? 4 replies
- What are the Nyāya hetvābhāsas, and do they line up with the Western list of fallacies? 4 replies
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