Ms. Smith: I am upset that my son's entire class lost two days of recess because some of the children were throwing raisins in the cafeteria.
Principal's Conclusion (Implicit)
It was appropriate that we docked the entire class two days of recess, even though not all of them were culprits.
Principal's Evidence
It's like being caught in a traffic jam caused by an accident. People who aren't involved in the accident nevertheless have to suffer by sitting in traffic until the road gets cleared.
Evaluate
The principal's argument relies on an analogy (this situation is like this other situation).
Whenever we're trying to weaken or object to an Analogy, we start by thinking to ourselves, "How are these two situations unfair to compare?"
If we were Ms. Smith, what could we say in response to the Principal's analogy?
We might say,
Goal
Let's look for an answer complaining that the two situations are not really fair to compare.