Using Evidence Strategically
A short guide to using evidence where it strengthens the argument, rather than adding data simply because it is available.
Evidence is most useful when it helps the reader accept a claim that might otherwise be doubted. It should not be added simply because the writer has collected it. Unnecessary evidence can make a document longer, slower and less persuasive by distracting from the central reasoning.
A strategic approach begins with the argument. First identify the claims the reader must accept for the document to succeed. Then ask which of those claims may have a credibility problem for this audience. Evidence belongs where it answers that problem.
In an argument map, evidence should be attached to the particular claim it supports. This matters because a citation, example or data point is not persuasive in the abstract. It becomes useful when the reader can see exactly which claim it is meant to strengthen.
Necessity: Does this evidence support a claim the audience may question?
Trustworthiness: Will this audience regard the source, method or authority as reliable?
Relevance: Does the evidence make the claim more likely, or could it be explained another way?
The same evidence can be persuasive for one audience and weak for another. A technical audience may value method, assumptions and data quality. A senior executive may need to know what the evidence means for risk, cost, capability, safety or strategic objectives. The writer's task is to connect the evidence to the reason it is being used to support.
Evidence should usually be placed close to the claim it supports. This helps readers see the role of the evidence rather than forcing them to remember disconnected facts. Where a document contains large amounts of data, the main text should explain the significance of the evidence and place detailed material in an appendix or supporting exhibit.
Used well, evidence does more than add authority. It helps show that the writer has tested the argument, anticipated reasonable doubt, and provided enough support for the reader to rely on the recommendation.
You may also be interested in the companion edVirtus course: Persuasive Presentations.