Argument from fallacy

An argument from fallacy is a formal fallacy which occurs when analyzing an argument and assuming that, because the argument contains a logical fallacy the conclusion of that argument must be false. It is also commonly referred to as the fallacist's fallacy.

Form
The form of the argument from fallacy requires a meta-argument, or an argument about the claims of an argument.


 * There is an argument A which has a conclusion C.
 * That argument A contains a logical fallacy.
 * Therefore, C is false.

The issue here is that while the presence of a fallacy is sufficient to render argument A invalid, it does not make C false. Rather, the truth value of C is unknown, because there is no valid argument as to whether C is true or false.

Example

 * Bob asserts that evolution is true.
 * Bob says it's true because Charles Darwin said so - which is an argument from authority, and thus a fallacy.
 * Therefore, evolution is false.