Why do People Support Abortion?

I honestly don’t understand how a rational person can support abortion rights.

To me, the argument against abortion is very simple, and goes something like this:

  1. Murder is the intentional killing of an innocent human being, and is immoral.
  2. Abortion is the intentional killing of an embryo or fetus.
  3. Embryos and fetuses are innocent human beings.
  4. Therefore, abortion is murder, and immoral.

The arguments for abortion rights seem to try to refute this argument in one of three ways:

  1. The most common argument is that embryos and fetuses are not human beings. However, I have yet to see a cogent rationale for this belief. Every argument I see is based on emotion or is utterly subjective.  Genetically, an embryo is human from the moment of conception. There is no other point in human development where scientists can objectively say, up this stage, the embryo/fetus is clearly not human, but from this point on, it is.
  2. The second common argument I see is that murder isn’t necessarily immoral. This view usually presupposes the first argument, that the unborn aren’t human beings. The rape, poverty, abuse, and birth defects arguments generally fit in this category. Sometimes, the “a woman’s choice” argument fits here as well. Again, I have yet to see a cogent rationalization for this view.
  3. The third argument I see is that abortion should be legal despite the fact that it is murder and immoral. This view is where the “a woman’s choice” argument usually fits. To me, this is the most illogical argument of the three. If murder by abortion should be legal, why not all forms of murder? Why make anything illegal?

The only justifiable exception I can logically defend is abortion to save the life of the mother. If both the mother and the fetus are expected to die without the abortion, and there is a reasonable expectation that the mother’s life can be saved if the abortion is performed, then it is better to lose one life than two. At the same time, every attempt should be made to save the baby as well.

I would very much like to understand why individuals who support the pro-choice position believe abortion is justifiable. If you are an abortion supporter, I would appreciate your comments. Please keep them respectful and on-topic. Disrespectful or irrelevant comments will be summarily deleted.