Argumentation Schemes and Fallacies

Fallacies are a subgroup of Argumentation Schemes. Argumentation Schemes are what are traditionally known as fallacies. Argumentation Schemes are only fallacies when used inappropriately. For example, the following argumentation schemes are valid in the appropriate context.
- Ad hominem, in a law trial when the witness is in the process of impeachment
- Appeal to Authority, when testimony from and expert witness is used
- Appeal to Pity, for circumstances, such as family or financial obligations, about the defendant that need to be considered
- Argument from Consequences, it is not a fallacy to argue that if you smoke you may get cancer.
- Affirming the consequent is how science works.

References:
http://en.wikipedia.org/wiki/Fallacies
The New Dialectic, Conversational Contexts of Argument by Douglas Walton.