This issue is a bit more vague, a bit harder to argue, but  one that I think should be argued. My main argument against allowing homosexuals to get married is that it adds a plasticity to the definition of marriage, that once followed, cannot logically be stopped.

The argument centers on what should the definition of marriage be? Who should that include? Traditionally marriage has been defined as the union between a man and a woman. The union of two men or two women was not recognized.
However, that definition is being changed, and same sex marriages in many states is being recognized.

Now, the reasoning behind the original definition was based on most importantly, religion, along with cultural reasoning. But the argument from the homosexual camp is that the state cannot enforce religion on its citizens, and that you cannot legislate morality. I have to disagree. As I stated in the Abortion article, every law on the books is someone's legislated morality. To some people, they find the murder of others to be allowed in their morality. And yet, the government enforces its morality on those people.

But here is where the real trouble steps in. Now, we are redefining marriage to allow the union of two consenting adults, even if they are of the same sex. But if the original definition of marriage has no absolute meaning, why should this new definition have any truth to it as well? Why can it not, logically, be extended to include two consenting people, even if that is an adult and a child?

Should we allow a man to marry a little boy, if both consent to it? If not, why not? Because once we say that the current definition of marriage has no absolute meaning to it, then the one we insert for it can be changed just as easily.

I, on the other hand, believe morality to be an absolute, that something is inherently right or inherently wrong, and that we either conform to that belief, or we don't. As such, I believe our definition of marriage either complies to an absolutely moral standard, or it does not.
One response would be that the world isn't just black and white. And my response would be that morality isn't a color wheel.