The law is not perfect by any means. I agree that any society that uses abortion merely as a means of contraception following careless planning is in moral decline. I believe it should be reserved for exceptional cases. But who decides what constitutes these cases. There are a myriad of valid reasons for and against deciding, that don't end with risk to the mother's life.
Incest, for example. Despite the obvious risks, I have had the privilege of meeting a very brave soldier who now works as a civil engineer in Israel, whose parents are in fact first cousins.
Conception from rape, for another. Imagine a mother going through with the birth and one day recognizing her attacker in the face of her beloved child. On the other hand, I know a grown child of rape, and in fact she is not only an important part of my life, she contributes such a great deal to society's good, her presence on or absence from this planet is immeasurable -- in George Bailey proportions. Her last birthday celebration filled her house to the rafters. I was a wanted child and spent my last birthday with her and noone else.
And in the long run, I can see a whole host of other reasons. Even in the case of couples who simply can't face up to an unplanned pregnancy. They didn't know enough to behave responsibly up to that point, and are now expected to take responsibility for another life. A recipe for disaster for three people or an adoption opportunity for a couple who can't have their own? Who can decide? Only the mother should.
This argument always brings to mind the silly moral dilemma / riddle about the woman who was pregnant, who had 8 kids already, three who were deaf, two who were blind, one mentally retarded, and she had syphilis. Would you recommend that she have an abortion? If you answered yes, like me, then you just opted to kill Ludwig Von Beethoven.
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The abortion argument boils down to deciding when life begins. The Catholic Church says "conception." The politicians say "birth." My rabbi says, "when the kids leave home and the dog dies."