Abstract
The problem of universals has been, and continues to be, one of the most important problems in philosophy. Although discussed by a variety of Arabic thinkers, it was Avicenna (d. 1037) who made the most significant contributions by reinterpreting the crucial terms of the debate in accordance with his notion of quiddity qua itself. He argued that a non-conditioned quiddity—also known as the natural universal (al-kullī al-ṭabīʿī)—existed in external particulars in the way that a part exists in the whole. This paper examines Quṭb al-Dīn al-Rāzī’s (d. 766/1364) criticisms of this theory.