A priori in the Thought of Kant, Heidegger, and Gadamer

This article seeks to explain the epistemological and ontological aspects of a priori. This concept plays a role in the thought of Kant as the consistency of essential and epistemological terms. And in Heidegger's and Gadamer's thoughts, it is present in other way. This article seeks to explain that the epistemological and ontological aspects of the former are reflected in Heidegger and Gadamer's thoughts. Kant uses it in the epistemological context, Heidegger in the ontological field, and Gadamer place on the combination of these two epistemological and ontological views. In short, a priori in Kant's epistemology is an integral part of the mind and is necessary for the realization of the reality and experience. In Heidegger's ontology, a priori is the former perception of being that the foundation of knowledge is in the realm of experience, and in Gadamer's thought, a priori is a rational necessity that the history of the individual and its belonging to the tradition and society are its ontological nature.