Evaluate source credibility using primary/secondary classification, internal/external criticism, triangulation, and misinformation detection. Use this skill when the user needs to assess whether information is trustworthy, evaluate research sources, fact-check claims, or detect misinformation — even if they say 'can I trust this source', 'is this real', 'how reliable is this data', or 'fact-check this for me'.
Source criticism is a systematic method for evaluating whether information is trustworthy. Originally from historical methodology, it's now essential for navigating an information environment flooded with misinformation, opinion-as-fact, and AI-generated content.
IRON LAW: No Source Is Automatically Trustworthy
Every source — including academic journals, government data, and news from
reputable outlets — has potential biases, errors, and limitations. Credibility
is assessed, not assumed. "It's from the New York Times / 中央社" is not
sufficient — WHAT are they reporting, based on WHAT evidence, and do other
sources corroborate it?
Primary sources: Direct evidence from the time/event (original documents, raw data, eyewitness accounts, original research, official records)
Secondary sources: Analysis or interpretation of primary sources (textbooks, review articles, news analysis, biographies)
Tertiary sources: Compilations of primary and secondary (encyclopedias, Wikipedia, databases) — starting points, not endpoints
1. External Criticism — Is the source authentic?
2. Internal Criticism — Is the content reliable?
3. Triangulation — Do multiple independent sources agree?
4. Currency — Is the information current enough?
| Red Flag | Description |
|---|---|
| No author or organization identified | Who stands behind this claim? |
| Emotional language without evidence | Designed to provoke, not inform |
| No primary sources cited | Claims without traceable evidence |
| "Studies show" without naming the study | Vague appeals to authority |
| Single source amplified across many sites | Same claim copied, not independently verified |
| Too good to be true / too outrageous | Extreme claims require extreme evidence |
| URL/domain mimics reputable source | Fakecnn.com, bbc-news.co (not bbc.co.uk) |
# Source Evaluation: {Source/Claim}
## Source Identity
- Author/Organization: {who}
- Publication: {where}
- Date: {when}
- Type: Primary / Secondary / Tertiary
## Credibility Assessment
| Test | Assessment | Evidence |
|------|-----------|---------|
| External (authentic?) | ✓/⚠/✗ | {reasoning} |
| Internal (reliable?) | ✓/⚠/✗ | {reasoning} |
| Triangulation (corroborated?) | ✓/⚠/✗ | {other sources checked} |
| Currency (current?) | ✓/⚠/✗ | {relevance of date} |
## Red Flags
- {any detected red flags}
## Verdict
- Credibility: High / Moderate / Low
- Recommended action: {trust / verify further / discard}
Scenario: Evaluating a viral social media post claiming "Taiwan's GDP will surpass South Korea's by 2027"
| Test | Assessment | Evidence |
|---|---|---|
| External | ⚠ | Anonymous account, no institutional affiliation, chart has no data source |
| Internal | ✗ | Uses nominal GDP (not PPP), cherry-picks semiconductor sector projection, ignores exchange rate volatility |
| Triangulation | ✗ | IMF and World Bank projections show no such convergence; no reputable analyst makes this claim |
| Currency | ✓ | Posted this month |
Red flags: Emotional headline ("Taiwan DESTROYS Korea"), no primary data source cited, single unsourced chart Verdict: Low credibility — discard ✓
references/craap-test.mdreferences/fact-check-tools.md