Curator: A magazine recently ran a very misleading story on the reaction of local residents to our controversial art exhibit.
Conclusion
The magazine story was very misleading in its story on .
Evidence
All three of the quoted residents were morally outraged, and this was meant to suggest that most local residents oppose the exhibit. But these three residents were close friends.
Evaluate
When we're trying to pick a Principle to conform to or justify an argument, we can generally just start with an "If Premise, then Conclusion" linking idea. This author is trying to prove that story was misleading.
Why is it misleading? The reactions of the three local residents quoted are supposed to suggest the reactions of most local residents, but the three quoted people were close friends.
So, the author must be assuming a principle like,
If three people then it's misleading to act are close friends → like their opinions represent those of most locals
Goal
The author is essentially mad that the magazine acted like 3 close friends are a "representative sample" of the majority of local opinion. So the author is also implicitly assuming that .