Existence predicate in Kant and Frege

The questions of how existence should be approached and what it means are central in philosophical discussions. Kant and Frege are two philosophers who try to determine the context of the issue in a different direction by challenging the traditional understanding of existence. Our main purpose in this study is to provide an explanation of what changes the expression "existence" have undergone in the context of Kant's and Frege's thoughts. While Kant uses the expression "Being is not a real predicate" in this respect, Frege defends the idea that existence is a quantifier. This means that the expression "exist" is accepted by both thinkers as a second-level predicate. However, despite this similarity, the theories of both philosophers differ significantly. As a matter of fact, Frege, with the effect of the emergence of non-Euclidean geometries, attempts to get rid of the emphasis on the intuition in the Kantian system and thus tries to avoid the psychologism that makes Kant's system defective. At this point, explaining what judgment means for Kant and Frege constitutes the first pillar in explaining the views of the two philosophers on existence. However, our goal here is to be able to conduct a research concerning the ontological grounds. In this direction, the main claim we have presented in terms of our thesis is that the lack of the concept of "world" of the Kantian system in the Fregean system caused some blurring in terms of ontology and semantics. As a matter of fact, this deficiency has its effect on the semantic tradition and contemporary philosophy of language debates after Fregean thought. For this reason, presenting a comparison of the areas to which the two thinkers ascribed existence will also explain whether they defend the same idea or not. Key Words: Kant, World, Existence, Frege, Thought