Full Idea
The proposition 'Consider whether your maxim can be asserted as a universal principle' would be all very well if we already had determinate principles concerning how to act.
Gist of Idea
The categorical imperative is fine if you already have a set of moral principles
Source
Georg W.F.Hegel (Elements of the Philosophy of Right [1821], 135 add)
Book Reference
Hegel,Georg W.F.: 'Elements of the Philosophy of Right', ed/tr. Wood,Allen W. [CUP 1991], p.163
A Reaction
Excellent! I have always taken this to be the overwhelming problem with Kant's theory. Kant's examples always presume a set of unquestioned conventional values. Kant offers a framework for moral thought, but values are what matter.