Accident fallacy

December 26th, 2005

Also known as:
destroying the exception
dicto simpliciter ad dictum secundum quid

This one is pretty easy to spot, and lots of people make this error. This fallacy is committed when you take a general rule and apply it to a specific case, yet it is obvious it doesn’t apply to that case. It’s a “general to exceptional specific” sort of error. Most rules we live by are general, and there are instances where exceptions to the rule are both expected, and required. Wikipedia gives an excellent example and I’m darned if I can think of a better one:

1. Cars should never exceed the speed limit.
2. Police cars are cars.
3. Therefore, police cars should never exceed the speed limit.

In more formal explanation, as you can see, this is a deductive, informal fallacy, where the categorical term ‘never’ is actually a general statement we neither believe to be the case, nor expect to be the case, with the specific term ‘police car’. Since there are times when we expect, want, and need a police car to exceed the speed limit, such as responding to an emergency, we can immediately spot that the major proposition of the syllogism is faulty, since we can easily bring to mind a necessary exception.

It’s fairly easy to remove or reduce the fallacy by qualifying the categorical term.

1. Cars should usually never exceed the speed limit.
2. Police cars are cars.
3. Therefore, police cars should usually never exceed the speed limit.

Note that people will generally use an accident fallacy when they are trying to bring fault against another (person or thing or argument), because pointing out the breaking of a unqualified rule emphasizes their position. Were they to qualify their argument, it would weaken their position, as the counter argument could then claim that they are arguing the exception to the qualified rule.

References:
Wikipedia
Bruce Thompson’s Fallacy Page-Accident