  Rehberg began his essay by expressing his agreement with the basic principles of Kant's moral philosophy.  Unlike many opponents of Kant's moral theory, Rehberg was not an empiricist in ethics.  He flatly denied that utility could settle matters of  right,[44]  and he held that the first principles of morality have to be established independent of experience, apart from any knowledge of the consequences of acting upon them.  It was Kant's great merit, Rehberg declares, to have shown that the first principle of morality— ‘Act so that the maxim of your will becomes a universal law’—is determinable by pure reason alone.  Where Rehberg disagrees with Kant is in his attempt to establish specific moral and political maxims from the first principle of morality.  Like many later critics of Kant, Rehberg maintains that the categorical imperative is a purely formal principle, insufficient to determine the content of our specific duties.  The categorical imperative amounts to nothing more than the general demand that our principles be universalizable, that they hold for everyone alike without exception, or that we treat like cases alike (117-118).  As such it provides a merely negative condition for accepting a moral principle; the problem is that it does not provide a positive criterion to distinguish between the many maxims that satisfy this condition.  The principle is still compatible with many different maxims, all of which are universalizable.  