Cheat sheets, checklists, and tools for rapid critical thinking application.
Fallacy Cheat Sheet
| Fallacy | Structure | Quick Example |
|---|
| Affirming the consequent | If P→Q; Q; ∴P | "If rain then wet. Wet. ∴Rain." (Sprinklers?) |
| Denying the antecedent | If P→Q; ¬P; ∴¬Q | "If rain then wet. No rain. ∴Not wet." (Sprinklers?) |
| Undistributed middle | All A=B; All C=B; ∴A=C | "Dogs are animals. Cats are animals. ∴Dogs are cats." |
| Illicit major/minor | All A=B; No C=A; ∴No C=B | "All roses are flowers. Daisies aren't roses. ∴Daisies aren't flowers." |
| Fallacy | One-Liner | Detection Question |
|---|
| Ad hominem | Attacking the person | "Does this address the argument or the arguer?" |
| Straw man | Misrepresenting the argument | "Is that what they actually said?" |
| Red herring | Changing the subject | "Does this relate to the original claim?" |
| Appeal to authority | "Expert says so" | "Is the expert qualified in THIS field?" |
| Appeal to popularity | "Everyone believes it" | "Popularity = truth?" |
| Appeal to tradition | "We've always done it" | "Is there evidence it's still the best way?" |
| Appeal to emotion | Substituting feelings for evidence | "Remove the emotion. What's the evidence?" |
| Appeal to ignorance | "Can't disprove it" | "Has the claimant met their burden of proof?" |
| False dilemma | Only two options presented | "Are there other options?" |
| Slippery slope | One step → catastrophe | "What's the evidence for each step in the chain?" |
| Tu quoque | "You do it too" | "Does hypocrisy invalidate the argument?" |
| Genetic fallacy | Judging by origin | "Is the origin relevant to the truth of the claim?" |
| Begging the question | Conclusion = premise | "Is the 'proof' just restating the claim?" |
| Burden of proof shift | "Prove me wrong" | "Who made the claim?" |
| Fallacy | One-Liner | Detection Question |
|---|
| Equivocation | Word used in two senses | "Is this word being used consistently?" |
| Composition | Parts → whole | "Does a property of parts apply to the whole?" |
| Division | Whole → parts | "Does a property of the whole apply to each part?" |
Statistical Fallacies
| Fallacy | One-Liner | Detection Question |
|---|
| Cherry-picking | Selective data | "What does the full dataset show?" |
| Survivorship bias | Only studying successes | "What about the failures?" |
| Gambler's fallacy | Past changes future odds | "Are these events independent?" |
| Base rate neglect | Ignoring prior probability | "What's the underlying frequency?" |
| Simpson's paradox | Aggregation reverses trends | "What do the subgroups show?" |
| Texas sharpshooter | Pattern found after the fact | "Was this predicted beforehand?" |
| Denominator blindness | Ignoring the total | "Out of how many?" |
Evidence Hierarchy
STRONGEST
│
│ ┌─────────────────────────────────────────┐
│ │ Systematic Reviews / Meta-analyses │
│ │ (Combine all studies on a topic) │
│ └─────────────────────────────────────────┘
│ ┌─────────────────────────────────────────┐
│ │ Randomized Controlled Trials (RCTs) │
│ │ (Gold standard for causation) │
│ └─────────────────────────────────────────┘
│ ┌─────────────────────────────────────────┐
│ │ Cohort Studies │
│ │ (Follow groups over time) │
│ └─────────────────────────────────────────┘
│ ┌─────────────────────────────────────────┐
│ │ Case-Control Studies │
│ │ (Compare outcomes to controls) │
│ └─────────────────────────────────────────┘
│ ┌─────────────────────────────────────────┐
│ │ Cross-Sectional Studies │
│ │ (Snapshot in time) │
│ └─────────────────────────────────────────┘
│ ┌─────────────────────────────────────────┐
│ │ Case Reports / Expert Opinion │
│ │ (Individual cases, professional judgment) │
│ └─────────────────────────────────────────┘
│ ┌─────────────────────────────────────────┐
│ │ Anecdotes / Personal Experience │
│ │ (Stories, "I heard that...") │
│ └─────────────────────────────────────────┘
│
WEAKEST
General Fact-Checking
| Site | Focus | URL |
|---|
| Snopes | Rumors, viral claims, urban legends | snopes.com |
| FactCheck.org | U.S. political claims | factcheck.org |
| PolitiFact | Political statements, Truth-O-Meter | politifact.com |
| Full Fact | UK-focused fact-checking | fullfact.org |
| AP Fact Check | Associated Press verification | apnews.com/hub/ap-fact-check |
| Reuters Fact Check | Global claims verification | reuters.com/fact-check |
| Site | What It Does | URL |
|---|
| AllSides | Media bias ratings, balanced news | allsides.com |
| Media Bias/Fact Check | Rates sources on bias and factual reporting | mediabiasfactcheck.com |
| Ad Fontes Media | Interactive media bias chart | adfontesmedia.com |
| Ground News | Shows how stories are covered across the spectrum | ground.news |
Image and Video Verification
| Tool | What It Does |
|---|
| Google Reverse Image Search | Find the original source of an image |
| TinEye | Reverse image search with date filtering |
| InVID | Video verification toolkit (browser extension) |
| FotoForensics | Image manipulation analysis |
Scientific Claims
| Resource | What It Does | URL |
|---|
| Cochrane Library | Systematic reviews of health evidence | cochranelibrary.com |
| PubMed | Database of biomedical literature | pubmed.ncbi.nlm.nih.gov |
| Retraction Watch | Tracks retracted scientific papers | retractionwatch.com |
| Our World in Data | Global statistics with context | ourworldindata.org |
| Google Scholar | Search academic literature | scholar.google.com |
Questions to Ask Checklist
For Any Claim
- [ ] What exactly is being claimed?
- [ ] What's the evidence?
- [ ] Who's making this claim and why?
- [ ] What's the strongest counter-argument?
- [ ] What would change my mind about this?
For News Stories
- [ ] Who published this and what's their track record?
- [ ] Are other reputable outlets reporting the same thing?
- [ ] What's the original source?
- [ ] What context might be missing?
- [ ] How old is this story?
For Scientific Claims
- [ ] Is this a single study or consensus?
- [ ] What was the sample size?
- [ ] Was there a control group?
- [ ] Has it been replicated?
- [ ] Who funded it?
- [ ] What's the effect size (not just significance)?
For Arguments
- [ ] What's the conclusion?
- [ ] What are the premises?
- [ ] Are the premises true?
- [ ] Does the conclusion follow from the premises?
- [ ] What's assumed but not stated?
- [ ] Is this the strongest version of the argument?
For Decisions
- [ ] What am I optimizing for?
- [ ] What are the alternatives I'm not considering?
- [ ] What's the worst case if I'm wrong?
- [ ] Am I being pressured by urgency?
- [ ] Would I advise someone else to make this decision?
For Your Own Thinking
- [ ] Am I reasoning toward a conclusion or from one?
- [ ] Would I accept this reasoning from my opponent?
- [ ] What's my confidence level (as a percentage)?
- [ ] What information would change my mind?
- [ ] Am I confusing "I feel this is true" with "this is true"?
Argument Evaluation Template
Use this template to evaluate any argument you encounter:
ARGUMENT EVALUATION
==================
1. CLAIM
What is being argued?
_________________________________________________
2. PREMISES
What reasons are given?
a. _____________________________________________
b. _____________________________________________
c. _____________________________________________
3. HIDDEN ASSUMPTIONS
What is assumed but not stated?
_________________________________________________
4. EVIDENCE QUALITY
[ ] Anecdotal [ ] Statistical [ ] Experimental
[ ] Expert testimony [ ] Systematic review
Sample size: ___ Replicated: Y/N Peer-reviewed: Y/N
5. LOGICAL VALIDITY
Does the conclusion follow from the premises?
[ ] Yes [ ] No [ ] Partially
If no, which fallacy? _________________________
6. COUNTER-ARGUMENTS
Strongest case against this argument:
_________________________________________________
7. OVERALL ASSESSMENT
Strength: [ ] Strong [ ] Moderate [ ] Weak
Confidence: ____%
Missing information: ___________________________
The SIFT Method (Quick Reference)
| Step | Action | Time |
|---|
| Stop | Pause. Don't react. | 2 sec |
| Investigate the source | Who is this? What's their reputation? | 30 sec |
| Find better coverage | What do other sources say? | 1 min |
| Trace claims | Find the original source. | 2 min |
Critical Thinking Decision Tree
You encounter a claim
│
▼
Does it matter? ─── No ──→ Move on
│
Yes
│
▼
Can you verify it in < 2 min? ─── Yes ──→ Verify (SIFT) ──→ Accept/Reject
│
No
│
▼
Is a decision required now? ─── No ──→ Bookmark, return when needed
│
Yes
│
▼
Apply full evaluation:
1. Identify the claim precisely
2. Check evidence quality
3. Check logical structure
4. Consider counter-arguments
5. Assess your confidence level
6. Decide proportional to evidence
Probability Calibration Guide
| Verbal Expression | Approximate Probability |
|---|
| "Virtually certain" | 95-99% |
| "Very likely" | 85-95% |
| "Likely" / "Probable" | 65-85% |
| "About even odds" | 45-55% |
| "Unlikely" | 15-35% |
| "Very unlikely" | 5-15% |
| "Virtually impossible" | 1-5% |
Use these when expressing confidence. "I'm about 70% confident this is true" is more honest and useful than "I think this is true."
Cognitive Bias Quick Checks
For detailed coverage, see decisions/02-cognitive-biases.md.
| Bias | One-Line Check |
|---|
| Confirmation | "Am I only looking for supporting evidence?" |
| Anchoring | "Am I over-weighting the first number I heard?" |
| Availability | "Am I judging by what comes to mind easily?" |
| Sunk cost | "Would I start this from scratch today?" |
| Dunning-Kruger | "Am I new enough to this that I don't know what I don't know?" |
| Status quo | "Am I preferring this because it's current, or because it's best?" |
| Framing | "Would I decide differently if this were framed differently?" |
| Halo effect | "Am I judging this on its merits or on something unrelated I like about it?" |
Recommended Reading by Subtopic
Logic and Reasoning
| Book | Author | Level |
|---|
| Being Logical | D.Q. McInerny | Beginner |
| A Rulebook for Arguments | Anthony Weston | Beginner |
| Thinking, Fast and Slow | Daniel Kahneman | Intermediate |
| An Introduction to Formal Logic | Peter Smith | Advanced |
Fallacies and Argumentation
| Book | Author | Level |
|---|
| Straight and Crooked Thinking | Robert Thouless | Beginner |
| Crimes Against Logic | Jamie Whyte | Beginner |
| The Art of Thinking Clearly | Rolf Dobelli | Beginner |
| Nonsense | Robert Gula | Intermediate |
Evidence and Statistics
| Book | Author | Level |
|---|
| How to Lie with Statistics | Darrell Huff | Beginner |
| Calling Bullshit | Bergstrom & West | Beginner |
| The Signal and the Noise | Nate Silver | Intermediate |
| Superforecasting | Philip Tetlock | Intermediate |
| Book | Author | Level |
|---|
| Factfulness | Hans Rosling | Beginner |
| The Scout Mindset | Julia Galef | Beginner |
| Merchants of Doubt | Oreskes & Conway | Intermediate |
| Trust Me, I'm Lying | Ryan Holiday | Intermediate |
Science Literacy
| Book | Author | Level |
|---|
| The Demon-Haunted World | Carl Sagan | Beginner |
| Bad Science | Ben Goldacre | Beginner |
| The Structure of Scientific Revolutions | Thomas Kuhn | Advanced |
Practical Application
| Book | Author | Level |
|---|
| Thinking in Bets | Annie Duke | Beginner |
| The Intelligence Trap | David Robson | Intermediate |
| Rationality | Steven Pinker | Intermediate |
| Good Judgment | Noreena Hertz | Intermediate |
Cross-References to Other Directories
| Topic | Where | What It Covers |
|---|
| Cognitive biases | decisions/02-cognitive-biases.md | Full bias catalog with counter-measures |
| Decision frameworks | decisions/ | Structured approaches to making decisions |
| Psychology of thinking | psychology/ | How the mind works; perception, memory, motivation |
| Philosophical reasoning | philosophy/ | Deeper epistemology and ethics |
| Persuasion and influence | communication/ | Ethical communication and influence |
| Negotiation tactics | negotiation/ | Negotiation-specific persuasion and counter-tactics |