<P> Kant then asks why we have to follow the principle of morality . Although we all may feel the force of our consciences, Kant, examining phenomena with a philosophical eye, is forced to "admit that no interest impels me to do so". He says that we clearly do "regard ourselves as free in acting and so to hold ourselves yet subject to certain laws" but wonders how this is possible . He then explains just how it is possible, by appealing to the two perspectives that we can consider ourselves under . According to Kant, human beings cannot know the ultimate structure of reality . Whilst humans experience the world as having three spatial dimensions and as being extended in time, we cannot say anything about how reality ultimately is, from a god's - eye perspective . From this god's - eye perspective the world may be nothing like the way it appears to human beings . We cannot get out of our heads and leave our human perspective on the world to know what it is like independently of our own viewpoint; we can only know about how the world appears to us, not about how the world is in itself . Kant calls the world as it appears to us from our point of view the world of sense or of appearances . The world from a god's - eye perspective is the world of things in themselves or the "world of understanding". It is the distinction between these two perspectives that Kant appeals to in explaining how freedom is possible . Insofar as we take ourselves to be exercising our free will, Kant argues, we have to consider ourselves from the perspective of the world of understanding . It is only in the world of understanding that it makes sense to talk of free wills . In the world of appearances, everything is determined by physical laws, and there is no room for a free will to change the course of events . If you consider yourself as part of the world of appearances, then you cannot think of yourself as having a will that brings things about . </P> <Dl> <Dt> Occupying Two Worlds </Dt> </Dl> <Dt> Occupying Two Worlds </Dt> <P> According to Kant, the categorical imperative is possible because whilst we can be thought of as members of both of these worlds (understanding and appearance), it is the world of understanding that "contains the ground of the world of sense (appearance) and so too of its laws ." What this means is that the world of understanding is more fundamental than or' grounds' the world of sense . Because of this, the moral law, which clearly applies to the world of understanding, also applies to the world of sense as well, because the world of understanding has priority . To put the point slightly differently: Because the world of understanding is more fundamental and primary, its laws hold for the world of sense too . So the moral law binds us even in the world of appearances . </P>

Kantian ethics groundwork of the metaphysic of morals