Clear and Distinct

Some scholars attribute to Descartes the thesis that being 'clear and distinct' is a characteristic of a 'true' idea, one which they analyze as being defended by 'circular' reasoning.  Now, that thesis is implicitly expressed in the Rules, and hence, without defense.  However, in part IV of the Discourse, he asserts that "things which we conceive clearly and distinctly are all true--remembering, however, that there is some difficulty in ascertaining which are those that we distinctly conceive".  Furthermore, in the Third Meditation, he explains that an idea that is perceived clearly and distinctly is a true idea only if it is not the product of a deceiving God.  So, at minimum, these passages suggest that his concept of 'clear and distinct' is dubious as an indication of Truth, and the difficulty is to glean from them whether or not it is wittingly so.  At face value, they do express a reconsideration of that status of the concept, in which case there is no circularity involved.