RESUMEN
This appearance condition of fallacies refers to the phenomenon of weak arguments, or moves in argumentation, appearing to be okay when really they aren't. Not all theorists agree that the appearance condition should be part of the conception of fallacies but this essay explores some of the consequences of including it. In particular, the differences between committing a fallacy, causing a fallacy and observing a fallacy are identified. The remainder of the paper is given over to discussing possible causes of mistakenly perceiving weak argumentation moves as okay. Among these are argument caused misperception, perspective caused misperception, discursive environment caused misperception and perceiver caused misperception. The discussion aims to be sufficiently general so that it can accommodate different models and standards of argumentation that make a place for fallacies.