If we assume that man creates God in man's own image and likeness, then (logically) man, not God, is the supreme ruler of the universe and the only standard for determining what is good or evil. Reality depends not on some objective actuality, but on subjective opinion. Everything becomes relative, based on the opinion of whoever can force others to accept his or her version of reality — for it becomes, ipso facto, reality by the mere fact that people "agree" on it. Black can become white, and up can become down, simply by convincing people that such is the case. You only think the Emperor is walking down the street naked, because your consciousness hasn't been raised and your perceptions corrected.
We can therefore easily understand the attraction that basing the natural law (and thus the social order) on the Will has for many people. In essence, you can do anything you want, as long as you have enough faith in your own interpretation, enough of an ego to maintain your position in the face of all argument and evidence to the contrary, enough inventiveness to dismiss objective facts and truth, and enough power to force others to comply with your will.
It is no accident that Leni Riefenstal's chronicle of the rise of the Nazi Party in Germany was titled, The Triumph of the Will. Nazism, which Dr. Rommen considered the culmination and necessary outcome of basing the natural law on the Will, nearly succeeded in imposing its personal morality on the whole world, and in destroying all notions of an objective moral standard that applies to every human being.
This is, in fact, why socialism, national or otherwise, is condemned by the Catholic Church, which bases its understanding of the natural law on the common, reasoned consent of all mankind as to what constitutes the good. It is not because socialism seeks the abolition of private property. Abolition of private property, acknowledged by Karl Marx as the essence of socialism, is nevertheless "only" a symptom of a much deeper problem: misunderstanding the nature of reality, of which God's Intellect, not any statement of His Will (however firmly believed), is the ultimate expression.
As Pope Pius XI stated in Quadragesimo Anno ("On the Restructuring of the Social Order"), 1931, "If Socialism, like all errors, contains some truth (which, moreover, the Supreme Pontiffs have never denied), it is based nevertheless on a theory of human society peculiar to itself and irreconcilable with true Christianity. Religious socialism, Christian socialism, are contradictory terms; no one can be at the same time a good Catholic and a true socialist." (§ 120).
The final issue we will consider in the next posting on this subject is why this is so, and why we can't simply base the natural law on our personal faith in something we believe to be a statement of God's Will without measuring it against the standard of human reason.