Which fallacy involves using the assertion or idea they want to prove as part of their proof?

Which fallacy involves using the assertion or idea they want to prove as part of their proof?

• A. Circulus in demonstrando
• B. Petitio principii
• C. Cum hoc ergo propter hoc
• D. Dictionary simpliciter

Answer: (A)

Circular reasoning is at work here. In this fallacy, the argument relies on the conclusion as part of its own proof—the claim being tested is assumed right in the premises, so there’s no independent evidence beyond the claim itself. That creates a loop: X is true because X proves it. An example would be saying “X is true because X says so” or “We should accept Y because Y is the source of truth,” which uses the conclusion as its support instead of offering separate reasons. This is why the reasoning doesn’t actually demonstrate X. The other options describe different patterns of error (like mistaking correlation for causation or a similar but distinct form of assuming the conclusion), but the defining feature here is the circular lift of the conclusion into the proof itself.

Circular reasoning is at work here. In this fallacy, the argument relies on the conclusion as part of its own proof—the claim being tested is assumed right in the premises, so there’s no independent evidence beyond the claim itself. That creates a loop: X is true because X proves it. An example would be saying “X is true because X says so” or “We should accept Y because Y is the source of truth,” which uses the conclusion as its support instead of offering separate reasons. This is why the reasoning doesn’t actually demonstrate X. The other options describe different patterns of error (like mistaking correlation for causation or a similar but distinct form of assuming the conclusion), but the defining feature here is the circular lift of the conclusion into the proof itself.