Bathroom Reader demonstrates why I tend to distrust "Natural Law" based arguments.
"Before forks became popular, the difference between common and refined people was the number of fingers they ate with. The upper classes used three; everyone used five. This began to change in the 11th Century, when tiny, two pronged forks became fashionable in Italian High Society. But they didn't catch on; the Catholic Church opposed them as unnatural (it was an insult to imply that the fingers God had given us for food weren't good enough for food)."
Now, if you have read the Bathroom reader series, you know that they are not the... kindest to things Christian, so this is probably not the best construction on the theology in play - however, it does show why I tend not to trust arguments based on "nature" or "natural law". It's the same why I don't like arguments that begin "it's obvious that _________." Sorry - often it isn't obvious - it's just an assumption.
I want specific evidence. I want a citation. Show me the Scriptures. I want the Word of God being expounded upon - give me an argument based upon the Word. I don't care what you think is right or wrong, what goes against what is natural or proper - if you are going to say that something is wrong and shall not be done -- show me.
I have no problem using forks. None. I don't think I've ever worried that I am using unnatural means of eating. Let's just base theological statements on what is revealed in the world.