Unfortunatly, neither side in the abortion debate seems to realize that any attempt at using logic to convince the opposing side is doomed to failure.

The paradox inherient in the abortion debate results from an inability to square a circle.

The square - Society generally accepts the principal that human life should be protected. The exceptions are war and in some jurisdictions, capital punishment.

The circle - It's impossible to precisely and objectively define the point during pregnancy when a fetus becomes "human life". Any means to do so involves some level of subjective evaluation. Subjective evaluation grounded in the "current wisdom" of science is no different than evaluation grounded in religious belief. Neither can be proven and in the case of scientific belief, is subject to change as the scientific process reveals more information.

One attempt to square the circle has been to rely on the concept of "viability". This is of course, the best example of how relying on science for a clear line fails.

This conflict will never resolve until the process of procreation is removed from the domain of human interaction. When creating a human being is only done in a labratory the current debate will be irrelevent and replaced by ethical issues that will make abortion pale in comparison.