Circular reasoning is a logical fallacy where the conclusion of an argument is assumed in the premise. Instead of offering independent support, the argument essentially says, “This is true because it is true.”
Classic Structure
Premise: X is true because of Y
Conclusion: Y is true because of X
Examples
- “Radiometric dating proves the age of rocks because we know how old the rocks are.” If the dating method is calibrated using assumptions about the rock’s age, it risks circularity.
- “Evolution is true because it says in biology textbooks.” The authority of the text is being justified by the text itself.
Implications
Circular reasoning does not necessarily mean the conclusion is false—but it does mean the argument fails to prove it.
