Circular reasoning

Circular reasoning is when you use the answer to support the answer—like saying "I'm right because I'm right." The reason and the conclusion are the same idea in different words, so no real progress is made. It's a subtype of begging the question: the argument loops back on itself. Listeners may not spot it at first because the wording changes slightly each time.

Examples

• Lie detectors work because they detect lies, and we know they detect lies because they work.

• She's the best candidate because she's the most qualified. When we asked why she's most qualified, it's because she's the best candidate.

• This treatment is effective because patients get better, and we know it works because the treatment is effective.

• The test is accurate because it measures what it's supposed to measure, and we know it measures that because the test is accurate.