Gradation and Similarity of Existence for Avicenna and Thomas Aquinas

The present article is seeking to investigate the question of why is, in Thomas Aquinas’ metaphysics, gradation in the concept of existence not imaginable in spite of his belief in similarity of existence. In addition to Aristotle, Thomas has followed Avicenna in many of his positions. Aristotle regarded “being” as something other than synonym and homonym. Avicenna divided “synonym” into two groups: “univocal” and “equivocal”, and considered the third usage of “term” for Aristotle to be in “equivocal synonym”. Since he believes in similarity between cause and effect, he defends gradation and gradation in the concept of existence. Although Thomas does not speak of “similarity in existence”, he speaks of a third type called “analogous term” along with synonym and homonym. Although linguistic analyses support the idea of synonymy of the “analogous terms” in Thomas’ philosophy and “gradation” in Avicenna’s, metaphysical analyses of similarity on the basis of proportion by the new scholars who study Thomas is different from gradation of the concept of existence. Their analysis of similarity on the basis of proportion is close to Avicenna’s gradation of existence. However, since Thomas does not believe in similarity between the creator and the created, we may not consider this analysis of the above scholars as a proper interpretation of Thomas’ view on similarity.