Types of evidence
Claims need support. Different kinds of evidence persuade different audiences, and each has strengths and limits.
Why evidence matters
Evidence turns opinion into argument. Readers have no reason to accept a claim simply because a writer asserts it. Evidence shows that a claim rests on something beyond personal preference and lets readers evaluate it for themselves.
Statistics and data
Numbers can show scale and patterns: 'Road deaths fell 25% in the decade after the speed limit change.' Statistics are persuasive but can mislead if taken out of context, based on poor samples, or presented selectively. Always ask where data come from and what they actually measure.
Examples and anecdotes
Specific examples make abstract claims concrete. A single vivid story can be powerful (pathos), but anecdotes are not proof of general patterns. Combine stories that illustrate with data that show how typical they are.
Expert testimony
Quotations or findings from recognised experts lend authority. They are strongest when the expert works in the relevant field, the claim reflects broader expert consensus, and the source is reputable. Be wary of experts speaking outside their field.
Textual evidence
In literary and rhetorical analysis, the main evidence is the text itself: quotations and specific details. Choose short, precise quotations that directly support your point, and always explain how they support it.
Primary and secondary sources
Primary sources are original materials: historical documents, interviews, survey data, experiments, novels, speeches. Secondary sources interpret or analyse primary sources: scholarly articles, textbooks, reviews. Strong research uses both, letting you engage directly with evidence and with others' interpretations.
Matching evidence to audience
Different audiences find different evidence persuasive. Scientists expect peer-reviewed data; a community meeting may respond more to local examples and testimony from neighbours; policymakers want costs and outcomes. Consider what your readers will trust.
Worked example
Claim: 'The town should fund a free summer lunch programme.' Evidence could include data that 40% of local students qualify for free school meals (statistics), a quotation from a paediatric nutritionist on summer hunger (expert testimony), a teacher's account of students returning in autumn underweight (anecdote), and results from a similar programme in a neighbouring town (example).
Key takeaways
Evidence turns opinion into argument. Statistics show scale but must be checked for context. Anecdotes illustrate but do not prove patterns. Expert testimony is strongest from relevant, consensus-aligned experts. Textual evidence supports analysis of texts. Primary sources are original; secondary sources interpret them. Choose evidence your audience will trust.
Flashcard
Support for a claim
Check your understanding
Why is a single moving anecdote not enough to prove that a policy works?