Circular Reasoning

Conceptual Overview

Circular reasoning, known in Latin as circulus in probando, is one of the informal Logical Fallacies wherein the conclusion of an argument is already contained within its premises.

This defect is fundamentally pragmatic, as the evidence provided requires as much proof as the claim itself, rendering the argument a matter of faith that fails to persuade anyone not already in agreement.

In modern discourse, this is synonymous with the fallacy of begging the question, or petitio principii. The primary logical failure in circularity is the lack of independent ground or evidence for the conclusion. Such reasoning often follows the form that A is true because B is true, and B is true because A is true.

Scientific and Inductive Circularity

A significant challenge in the philosophy of science is the problem of induction, which is inherently circular. Scientists discover the laws of nature to predict future events through inductive reasoning. However, justifying induction requires an appeal to the principle of the uniformity of nature. Since the uniformity of nature is itself an inductive principle, any attempt to justify the scientific method using the scientific method results in circular reasoning.

What are considered 'facts' in science are often the result of unconscious judgment rather than direct sensation. Acquired perceptions allow the mind to judge distance or identity based on long experience, which can lead to circularity if the observer fails to discriminate between what is witnessed and what is inferred. This risk is heightened when observers only record facts that support a pre-existing theory, such as the influence of the moon on weather patterns.