# Logical fallacy

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A '''logical fallacy''' can be any one of a number of formal or informal mistakes in a deductive proof. | A '''logical fallacy''' can be any one of a number of formal or informal mistakes in a deductive proof. | ||

## Revision as of 16:46, 9 September 2006

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A **logical fallacy** can be any one of a number of formal or informal mistakes in a deductive proof.

Note that an argument can be fallacious but still correct. For instance:

- All fish live in the water.
- All trout live in the water.
- Therefore all trout are fish.

The premises are accurate and the conclusion is accurate, but the conclusion is not a valid inference from the premises. To see why, notice that we could use identical reasoning to prove that "all whales are fish."

Likewise, an argument can be logically valid but still wrong.

- All bugs are insects.
- All spiders are bugs.
- Therefore, all spiders are insects.

Some of the premises are factually incorrect, and the conclusion is also untrue. However, the conclusion is an accurate deduction based on those premises. Validity and soundness are also discussed in the relevant article.

For examples of logical fallacies, visit the logical fallacies category.

## External Links

Logic & Fallacies: Constructing a Logical Argument at The Secular Web