Logical fallacy

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:

1. All cats are mammals.
2. All cats are dogs.
3. Therefore all dogs are mammals.

The conclusion is accurate even though the premises and deductive method are incorrect.

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

1. All bugs are insects.
2. All spiders are bugs.
3. Therefore, all spiders are insects.

Some of the premises are factually incorrect. However, the conclusion based is an accurate deduction based on those premises.