Abstract
One of the most widespread claims combining epistemology and metaphysics in post-Avicennian Islamic philosophy was that every object of thought is real. In Muʿtazilite reading, it was endorsed due to a theory of knowledge which states that knowledge is a connection or relation between the knower and the object known. Avicennists accepted it due to the rule that in a proposition “s is p” if p is something positive s has to be positive and real too. Hence, insofar as one can conceptually distinguish between two non-existent items, they have to be real. In this article, the author presents significant consequences of this theory: the acceptance and denial of non-existent yet real extramental objects; the concept of mental existence as an alternative solution; the conceivability of paraconsistent ideas and their reality or reducibility to some real objects.