Silber's Argumentative Analysis

Silber says these rules are postulates of rationality since applying these rules in moral law could guarantee a rational consequence in a requisite sense. He explains: ‘‘only if the norms of morality, rules of thought and rules of aesthetic evaluation are treated as descriptive procedures, then there can be initially rational knowledge in science, the free play of sensibility and recognizing in aesthetic experience, autonomous action in moral experience’’ (Silber 200).
Through postulates of rationality, Silber understands Kant to imply that his readers should follow the pragmatic rational-directed procedural ethic as he explains in the following:

The procedurals of judgments in ethics. The procedural interpretation of rationality, that is,

But this natural law can be used only in its formal aspect, for the purpose of judgment, and it may therefore be called the typic of the moral law……Now everyone knows very well that if he secretly permits himself to deceive, it does not follow that everyone else will do so, or that if, unnoticed by others, he is lacking in compassion, it does not mean that everyone else will immediately take the same attitude toward him. This comparisons of the maxims of his actions with a universal natural law, therefore, is not the determining ground of his will. But such a law is still the type for the estimation of maxims according to moral principles. If the maxim of action is not so constituted as to stand the test of being made the form of a natural law in general, it is morally impossible, though it may still be possible in nature.

These critics want to make the test of C1 capable of generating results by suggesting that we ought to include background theory summarized in some common-sense rules. Such rules are called, variously, postulates of rationality by Silber, constraining principles of empirical, practical reason by Rawls, and principles of rational intending by O’Neill. Silber, Rawls, and O’Neill share a strategy of demonstrating that a moral test can be made by C1. In order to judge right or wrong, they essentially agree on where their theories lead, but disagree on how to get there. For instance, for Silber, C1 needs supplemental postulates which hold for all rational disciplines by employing sufficient common-sense principles. For Rawls, we may succeed by placing a certain kind of agent in a certain socio-political perspective in a deliberative situation with other like agents.
Those formalists attempt to enhance Kant’s moral test by adding a declarative set of subsidiary maxims (O’Neill) and other ‘buttressing’ rules (Silber and Rawls). The ethical judgment, then, becomes an outcome of the consistency test. While this kind of test can generate results, it may be vacuous in the sense that it would do no more than forbid obviously contradictory maxims of