By now you know that good evidence is factual. But the kinds of facts you need to gather depend on your audience. Why is this so? Think about the pet cat example you read earlier in this lesson. The audience for that argument was your parents. You and your parents share a common knowledge of pets and of your household's rules. You were able to gather evidence just by thinking, without having to do in-depth research. But what if your audience was the tenants' association of your apartment building? What sort of evidence would you need to persuade that group to let a pet cat live in the building?
For a formal presentation to a governing body (a tenants' association is a type of governing body), you would need to cite evidence from published reports, statistics from the city's animal control office, even expert testimony from a veterinarian on the suitability of cats to apartment dwelling.
The nature of your audience and its expectations should help guide you in gathering appropriate evidence to support your claims. Informal audiences are more likely to accept common knowledge and anecdotal evidence. Formal audiences usually require evidence based on research and expert knowledge.
Question
What if you helped out at an animal shelter's festival booth, trying to convince passersby to adopt a kitten? Would your argument be formal or informal?
In that situation, your argument would appear in friendly conversation, so it would stay fairly informal. You would use reasons and evidence similar to what you told your parents, but not as personal.
