Even setting aside that problem, you completely fail to address the artificial sweetener example. Fat is certainly a "natural response" to calorie consumption, but even your convoluted argument has no way of redefining it as a "natural defense" against anything.
I don’t understand your resistance here. The position is clear: No one is saying a woman can’t take something to aleviate the symptoms that come along with natural fertility cycles (I single out women here since men suffer no such symptoms with their fertility), just that to take contraceptives for that purpose is wrong since it interferes with the process of reproduction. This is the Catholic perspective of course.
The only issue one can have against the Catholic position is to say, “Well why is contraception ITSELF bad?”, because we aren’t saying alleviating symptoms or results of certain biological functions is bad. For the answer to the truly relevant question of, “Well, why is contraception ITSELF bad?”, I’d refer anyone to the OP of this thread.
Any other discussion is irrelevant. Fertility is not a disease. It’s not something harmful to the human body, in of itself. It’s not fat. It’s not a sore throat. It’s not cancer. It’s not myopia. It’s not sunburn. It’s not anything negative. It’s simply erroneous and faulty logic to equate it with something destructive to humanity as a whole; in fact I’d submit it’s rather laughable to do so. Without fertility, the human race would not exist! That’s basic common sense.
I submit, with all due respect, it is you who is engaging in circular reasoning by assuming your proposition (any biological function that has negative consequences one should be free to treat any way one wishes) in your proof (fertility can have negative physical consequences for a woman, therefore to limit chemical contraceptives is to limit all physical treatments).
Either that, or you are making the preposterous claim that somehow, fertility itself is “bad”. Not the symptoms/affects of fertility, but the actual production of the egg/sperm itself. Which *is* preposterous for reasons that should be obvious.