The first article of the cycle “The role of skeptical evidence in the First and Second ‘Meditations’” compares the Cartesian and Sextus Empiricus’ concepts of doubt in, respectively, “Metaphysical meditations” and “Outlines of Pyrrhonism”. The article starts with the current state of the problem “Descartes and skepticism” and admits the existence of consensus about Cartesian perception of skeptical tradition: Cartesius (1) was influenced by all skeptical movements, known in his time, and (2) created a generalized notion that contains elements of (...) both Academic and Pyrrhonian origin. This consensus is the source of many contemporary studies on how different skeptical doctrines influenced certain parts of Cartesian philosophy. This article attempts to analyze possible Descartes’ use of Sextus Empiricus’ notion of phenomenon. Sextus clearly states in “Outlines of Pyrrhonism” that one cannot doubt phenomenon as something perceived directly. The article proves that (a) Sextus’ thesis about the “sensory” nature of phenomenon is metaphorical, so far as it includes (without distinction) both sensuality and the experience of thinking; (b) the phenomenon is realized through a wide range of passive states of mind that all have irresistible force of influence; (c) the impact of phenomena is always mediated by our self, because all skeptical phrases are strictly correlated with the first person singular. Some researchers distinguish Sextus’ isostenia, as one of such insurmountable states, from Cartesian doubt at the First Meditation, which is allegedly based on a purely volitional decision. The article proved that this argument is artificial, since Descartes’ volitional decision is caused by initial inability to take the dubious as if it were certain. Thus, Cartesian approach can be considered a specific kind of isostenia. Such parallelism is a reason to assume a key role of Sextus’ understanding of insurmountable power of phenomena in Cartesian anti-sceptical argumentation. This assumption will be tested in the following articles of the cycle. (shrink)