MOST COMMON FALLACIES: #4 APPEAL TO IGNORANCE Definition and explanation: The argument from ignorance fallacy asserts that something is true, because we don’t know that it’s not. A foundation of critical thinking is that claims require evidence, and claims without evidence can be dismissed without evidence. A lack of evidence simply demonstrates our ignorance, and is not a reason to believe. This fallacy is commonly used by science deniers, pseudoscience proponents, conspiracy theorists, and bel