A circular argument is a logical fallacy where the conclusion is included in the premise, making the argument go in a loop without providing real evidence. For example, saying "I am trustworthy because I always tell the truth" assumes the conclusion (being trustworthy) without proving it. This type of reasoning is often unconvincing because it doesn't offer new information or support. Instead, it relies on the same statement to validate itself. Recognizing circular arguments is important in critical thinking, as it helps identify flawed reasoning in discussions or debates about topics like politics or philosophy.