  In other cases, however, Descartes describes the senses as providing material for error, but it remains uncertain whether he assimilates  such error to what has been labelled cognitive error or to sensory  misrepresentation. In the Third Meditation, he describes color sensations and other sensations of so-called “secondary  qualities” as “materially  false.” Scholars have found it difficult to  interpret the notion of material falsity, partly because  Descartes' discussion of it in the Third Meditation seems to offer  two possibilities, and partly because his long discussion of the issue  in the Fourth Replies, in response to Arnauld's  Objections, is intricate and seemingly contradictory.