Topics Logic

Question What fallacy is being committed here: I owned two Chevy cars – a Cruze and a Malibu – and they gave me nothing but trouble. The choke and the batteries froze up and the clutches went out on both cars. They were always in the shop. Chevy’s are poorly constructed and should be avoided. What fallacy does this person commit? fallacy of hasty generalization or fallacy of composition? It is difficult to tell if the argument assumes that parts of the Chevy car are troublesome (batteries, clutch etc.) therefore the whole Chevy car is poorly constructed making this a composition fallacy or if the person has observed a small amount of Chevy cars and made a generalization about the whole of Chevy cars which in this case it would be a hasty generalization fallacy. These fallacies are hard to tell apart and a little confusing.

Accepted:
January 12, 2020

Comments

The fallacy of composition is

The fallacy of composition is drawing conclusions about the whole from facts about the parts when the facts about the parts don't support the conclusion. Obvious case: every cell in my body weighs less than a pound. But that doesn't support the conclusion that I weigh less than a pound. The fallacy of composition is an informal fallacy: you can't tell whether it's been committed just by looking at the form of the inference while ignoring the content.

In any case, the inference you're considering isn't a conclusion about a particular car—a whole—based on premises about its parts. It's a conclusion about all or most cars of a certain sort based on facts about some cars of that sort. This doesn't count as a part/whole relationship in the sense relevant for potential cases of the fallacy of composition. "Chevy cars" aren't a whole in the relevant sense.

On the other hand, it would be hasty to generalize about Chevies based on a sample of two. So yes: hasty generalization.

A footnote, however: even people who've taught informal logic are often bad at naming fallacies; I certainly am. That's because the names aren't really important. What's important is being able to say what's gone wrong. Saying that an argument commits a petitio principii or the homunculus fallacy (I didn't know what that was either until five minutes ago) won't help most people unless they already know what these terms mean. And most of the time, they won't.