The Categorical Imperative and Moral Relativism

I have been trying now for several years to write some kind of essay explaining what I think is wrong with moral relativism as a philosophy. I don't think moral relativism is "incorrect" per se, but my instincts tell me that it is dangerous not to balance it with some belief in an absolute reality and an absolute morality. Suffice it for now to say that I think one ought to believe, paradoxically, in both the purely relative nature of reality as well as the purely, absolutely objective natural universe, and that only by holding this paradox in mind can one understand and participate fully in reality. Also, only by valuing both sides equally can one be a truly "moral" person.

My new plan of attack is to try to use Kant's categorical imperative as a wedge to crack open the hedonistic, lazy moral relativism that has grasped so many of my peers. Briefly stated, the categorical imperative is essentially this:

"Act only according to that maxim whereby you can at the same time will that it should become a universal law."

This 'imperative' almost perfectly captures the paradox that I'm grappling with. It can be contrasted with 'hypothetical imperatives' like, "If I wish to stay cool, I should avoid the hot desert." The problem with moral relativism is that it puts things on equal footings that shouldn't be. All opinions are not equally valid, as long as a reason for them is hypothesized. One need not believe that everyone has a right to be heard, or that everyone's opinion is equally valid, to believe that all people are equal. The belief that we need to be more "the same" (that it's desirable for us to have the same material comforts, the same place in society, the same natural and unnatural advantages and opportunities) is a form of socially entropy that threatens to homogenize and thereby destroy society.

We need a categorically imperative approach to issues like equality, fairness, and justice in society. If we believed, essentially, that only those things which we could universalize could contain "moral" insights, then we would not impose the will of the majority, the popular sentiment, or any of the other adversarial notions of morality upon people.

An application of the categorical imperative might look something like this:
1) We shouldn't allow some killing of humans unless we would allow all people to kill. We don't want to allow all people to kill, because it violates our natural sense of what is right and wrong. Therefore, murder is generally prohibited. But what about killing in self-defense?
2) We refine the approach thus: We shouldn't allow killing unless it is justified. Then, self-defense, war, and execution all potentially have a place in our morality. But then, how do we justify killing?
3) We refine the approach further: Killing is justified when inalienable human rights such as life or liberty are taken away or threatened. We have thus defined categorical imperatives that life and liberty ought to be granted to all.
4) We have thus justified killing if it protects life or liberty. This allows us to make decisions like the decision to assassinate a butcher before he murders 100 people. We then run into problems about what is required to "prove" that he was going to kill 100 people. This eventually leads to further imperatives.

These issues are inherently "moral" issues, because we force ourselves to evaluate whether principles are universalizable or not. This approach admits both absolutism and relativism. Without both, we are making a system that only applies to half of life, or a system that does no more than say that if we believe something.