This article actually does a good job of explaining both sides of these 'logical fallacies' including why they aren't always invalid. It's the best job I've see

This article actually does a good job of explaining both sides of these 'logical fallacies' including why they aren't always invalid. It's the best job I've seen so far of refuting the 'Fallacy Fallacy'. In particular it points out how the 'burden of proof' plays a big part in determining the validity of some arguments.