 One defense of the Intuition/Deduction thesis assumes that we know some substantive external world truths, adds an analysis of what knowledge requires, and concludes that our knowledge must result from intuition and deduction. Rationalists and empiricists alike claim that certainty is required for scientia (which is a type of absolute knowledge of the necessary connections that would explain why certain things are a certain way) and that certainty about the external world is beyond what empirical evidence can provide. Empiricists seem happy to then conclude that the type of knowledge of the external world that we can aquire does not have this high degree of certainty and is, thus, not scientia. This is because we can never be sure our sensory impressions are not part of a dream or a massive, demon orchestrated, deception. A rationalist like Descartes of the Meditations, claims that only intuition can provide the certainty needed for such knowledge. This, after his arguing in the Rules that, when we “review all the actions of the intellect by means of which we are able to arrive at a knowledge of things with no fear of being mistaken,” we “recognize only two: intuition and deduction” (Rules, Rule III, p. 3).