The broad outlines of the argumentative strategy for this meditation and the next is laid out here: the meditator now seeks a criterion to go on with: A rule that will allow him to decide what is certainly true: begins by reviewing his progress in 3. 01: He is certain that these modes of thinking qua modes do exist within me : the problem of the criterion is introduced in 3. 02. Since the meditator is certain he is a thinking thing, he asks whether he also knows what is required to be certain of something. Only thing he has to go on is a clear knows and distinct perception that he is a thinking thing, but that seems good enough; he concludes at the end of 3. 02: So i seem now to be able to lay it down as a general rule that whatever i perceive very clearly and distinctly is true.