The morality of abortion hinges on different criteria depending on who it is you are having the discussion with. One of the most persistent defenses for abortion is the question of when life begins. This is a question only asked by those philosophizing about abortion, not among those in the embryological sciences. The moment a new human life begins is the instant the sperm enters the egg. But some will argue otherwise: Since we don’t know the precise moment in time the new life begins, it is morally permissible to have an abortion. Personally, I find arguing for abortion from medical ignorance morally and ethically irresponsible. After all, if you don’t know, wouldn’t it be prudent to err on the side of life? But for the sake of argument, let’s agree and say we don’t know when life begins. What does that mean for the abortion debate? Nothing.
Abortions are not performed until well after the mother is determined to be pregnant. The earliest a pregnancy can be detected is between one and two weeks after fertilization. However, the majority of women will not begin to suspect pregnancy until after a missed cycle which could take a few weeks after fertilization.
So what does this mean? All elective and medically necessary abortions — without exception — are performed long after the fertilized egg is indisputably established to be alive. 62.8% of abortions are had by 8 weeks, at which point fingers and toes are taking shape, heart beat has already been established, and brain function is present. Another 28.6% of abortion happen by 13 weeks, at which point fingerprints have formed, veins and organs are visible, and the baby can respond to outside stimuli.
The objection that we don’t know when life begins is a distraction. When life precisely begins is completely irrelevant to the abortion issue because of when abortions are performed. But also, when life begins seems also to be irrelevant to the objector offering the objection anyway. With the exception of possibly two people, I haven’t had anyone who has offered this objection change their mind on abortion once informed about when life begins, or abandon the argument. Those who defended abortion with ‘we don’t know’ but then shown their error and dig their heels in nonetheless exposes how deeply wedded to abortion they are.
This is not to say arguing the pro-life position is fruitless, many people come to change their pro-choice view, I did. And the discussion can be beneficial to those who may be on the fence. The information is readily available to anyone who earnestly seeks to find it. But I think the person defending elective abortion by claiming ignorance as to when life begins is offering a vacuous and irrelevant argument. It flies in the face of medical fact and practical application. I suggest before addressing the ‘when does life begin’ defense of elective abortion, we should ask if their stance on abortion would change if it could be shown that we do in fact know when life begins.
Sifting Reality 
I agree that a new life begins at conception but am still pro-abortion. Not all life has equal value, so the life of the mother is usually more valuable at that time to society than the life of the fetus or baby. If an abortion improves the quality of her life then society should support that decision. The mother is often in the best position to make this decision.
What if putting a gun to your head improves my life?
How would that improve your life? Can you think of a possible scenario where that would improve your life? A mothers kills her child to avoid the burden of care. Also, I would attempt to defend myself while a fetus or baby cannot defend themselves.
Im a pretty good shot and a very quick draw. But it would improve my life by increasing my overall happiness. Thats enough improvement by my standard.
Have you had prior experience where killing has improved your life? You may think it would improve your life, but I think you are mistaken and instead you would feel guilt.
It would improve my life just trying it. Im willing to risk it, and your view cant argue against it
You may be a psychopath if you think that killing will make you feel happy. Mothers kill their children not to feel happy, but to prevent suffering for their child or their family.
In the past when a family was suffering from the burden of a sick child they would claim their child had been replaced by a changeling. This would allow parents to kill the sick child with less guilt, http://www.pitt.edu/~dash/changeling.html
In the same way many who are pro-abortion claim the fetus is not human to reduce their guilt.
…and I’m the psychopath.
I don’t know why you bother with that nutjob, John. Same guy who has argued in favor of infanticide.