The Views of Fakhr al- Din al-Razi and Khajeh Nasir al-Din al-Tusi on the Ontology of Universals

The problem of universals can be examined from two aspects: ontological (the state of the external existence of universals) and epistemological (our cognition of universals). This article mainly concerns the ontological aspect. Both of Fakhr al-Din Razi and Khajeh Nasir al-Din Tusi have furnished us with novel views and insights which, in spite of their significance and freshness, have not been yet studied seriously. This paper deals with their views on the ontology of universals. We conclude that they have almost similar opinions about the three different meanings of ‘kulli’ (universal) and three kinds of consideration of quiddity. Nevertheless, their elucidations and refinements of the ontological state of these three kinds of universals are totally different. Moreover, al-Razi’s view on the rational universal (al-kulli al-aqli) and Tusi’s interpretation of the natural universal (al-kulli al-tabi’ee) seems questionable.