Usually, I don't cover hot-button issues like abortion. So much has been said on the subject, there's nothing new I can add. And I'm a man so I don't feel empowered to impose my beliefs on others who might personally face this situation. Nevertheless, The Dallas Morning News's Jeffrey Weiss's always thoughtful Facebook feed suckered me in. To preserve my thoughts (which might be of interest to a distant future me, if no one else), here's what I had to say on the subject. I'm not including the context that prompted me to jump in, but I think what I say can stand alone.
Using viability of the fetus as a dividing line for legal abortion is, as its critics insist, an arbitrary and ever-shifting line in the sand. As Jeffery points out, the day might soon be coming when any cell from any part of the body might be a viable start for a new, independent human life. Given expected scientific advances, how does a law based on viability not also eventually give legal protection to, say, nail clippings? That's the kind of question lawyers have to wrestle with.
There are different markers that could be used to decide between legal and illegal abortion. Viability is one. Heartbeat is a possible workable marker. So is birth. So is conception. It's a value judgment by society, not a question that can be answered scientifically. And society has made different judgments in different places at different times.
Some looking for a more absolute test ask, "When does life begin?" The scientific answer is that, as far as we know, life began about 4 billion years ago and has been going on uninterrupted ever since. Most people think of a fertilized egg as the way adults of a species continue the species. But from a different perspective, the adults are just DNA's way of continuing the existence of DNA. The lives of chromosomes just go on and on forever, temporarily pairing up in different ways. These pairings make for convenient ways to draw arbitrary legal lines in the sand, but they are no less arbitrary than other lines.
The law draws arbitrary and ever-shifting lines in the sand all the time. Doing that wisely is what the law is all about. I don't have the absolute answers. Neither does science. Neither does anyone else.