In a sense, freedom is one of the most important concepts in the history of philosophy, which plays a fundamental role in the thought of philosophers, but like many other concepts, it needs to be redefined in order to survive in new conditions. Based on this, this article aims to compare Kant's and Heidegger's viewpoints and take some serious criticisms into consideration in order to take a preliminary step towards redefining the concept of freedom. Kant considers freedom to be a metaphenomenal matter and a fundamental characteristic of the subject. And he introduces it as the foundation of ethics. He chooses the positive meaning of freedom that emerges in the shadow of human socialization and makes it the basis of his thought. But it must ...