The last fallacy of this unit is the mirror image of hasty generalization. There the rule was bad; here the rule is good but misapplied.
Key idea
Accident applies a general rule to a special case that the rule was never meant to cover.
Why it works
Most rules are made for ordinary cases and have unstated exceptions. "No running in the halls" is about safety on normal days; running out during a fire alarm serves the same safety goal. Forcing the rule onto the special case defeats its purpose.
Worked example: A special case
"People should keep their promises. Ava promised to meet Ben at noon, but she stopped to help a child who fell off a bike. So Ava did something wrong."
- Keeping promises is a good rule.
- It was never meant to forbid helping someone who is hurt.
Answer: Accident.
Worked example: An ordinary case
"Library books are due in three weeks. Leo's book is five weeks old and nothing special delayed it. So Leo owes the late fee."
- Is anything special about this case? No: nothing delayed the book.
- This is the very kind of case the rule was written for.
Answer: Not a fallacy.
Common mistake
Calling this hasty generalization. In accident, the rule is fine in general; the mistake is forcing it onto an exception. In hasty generalization, the rule itself was drawn from too few cases.