In the work of Quintus Cornificius Rhetorica ad Herennium (CORN., II.25.39) we encounter arguments that are considered flawed by the Roman rhetorician but resemble apagogical arguments. The article is devoted to the analysis of this fragment of deliberations from Rhetorica ad Herennium. The author shows that they can be considered both as quasi-enthymematic reasoning and as an imperfect form of apagogical reasoning and maybe also abductive reasoning. This type of reasoning, according to the researcher, is one of the possible sources of fake news.