Metaphysics and theology
All critiques exercise reason and question grounds, but only some seek to interrogate the ground of reason itself. At a certain level of generality the enterprise of offering a critique of reason is circular, since the very distinctions which permit the operation of critique are themselves conditioned by reason. Upon closer inspection, however, it becomes clear that the circle need not be vicious and that such a critique can be lodged. One needs, first of all, to distinguish between offering specific reasons to justify a particular position, as all philosophers do, and construing reason as a ground, such as in the Leibnizian principle of sufficient reason. And second, one needs to demonstrate that reason, thus defined, is blind to its condition of possibility. The question arises, though, just how far the critique is to be taken. For in specifying the condition of reason's possibility one also begins a process of supplying another ground, such as the will or being; and while this new ground may differ importantly from reason, its function as ground will remain unchallenged. We must ask, then, whether the object of a critique of reason is 'reason' or the more fundamental and redoubtable notion of 'ground' itself. Modern philosophy offers examples of both kinds of critique, and matters are complicated by the fact that the critique of ground often develops by way of a critique of reason. Such is the case with Nietzsche, and the concerns of this chapter may be brought into focus by a brief comparison and contrast between this mode of critique and the other mode, exemplified by Kant, which questions reason though not 'ground' as such.
It is this critique of ground, unbroached by Kant, which interested Nietzsche and which, in his last writings, he sought to affirm: in part by extending the bounds of the Kantian problem-