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 no- tion 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 exa- mines Quṭb al-Dīn al-Rāzī’s (d. 766/1364) criticisms of this theory