The theoretical framework of Kant’s critical philosophy rooted in 18th century events (Enlightenment). The question of validity, scope and foundations of metaphysical knowledge is amongst Kant’s epistemological concerns. When we talk about “the possibility of metaphysics” we think about theoretical foundations of that knowledge. Science and experience for Kant means objective scope of human knowledge reflected in the sensibility and understanding. Here that very question again rise: the possibility of “pure mathematics” and “natural sciences”. Kant’s inquiries about this two scopes result in that though the theoretical foundations of knowledge belong to knowing subject, the process of mind’s activity belong to experience, and thereby the problem of the gap between subject and object will be solved. This approach extends to the scope of morality and religion, and provide an answer to the unsolved questions of metaphysics. On Kant’s view there is no conflict between theoretical and practical reason. If science deals with the objects of experience and concrete matters, and the possibility of mathematics and natural sciences is certainly undeniable, morality and religion specially deals with the existence of God and immortality of soul. When Kant think about moral action, its possibility and conditions, sees the correlation between them, and certainly concentrate on unobjectivity and nominal aspect of these matters.