The S in the SLED acronym stands for size. All of us began our lives as a tiny fertilized egg, or zygote, invisible to the naked eye. Over the years, the “smallness” of unborn babies has been cited to justify their murder.
Biologically, the human zygote is indisputably a member of the species Homo sapiens. Zygotes grow remarkably quickly and within 5-8 days implant in the uterine wall. Although the cells divide and differentiate, they have their own distinct DNA from the point of conception. Thus there is no genetic distinction between a person as a zygote, a newborn, and a full grown adult.
So does the size of a person dictate his or her right not to be killed? Is there are moral distinction between killing a tiny human and killing a larger human? Certainly, we reject this idea outside the womb. We would never say it was permissible to end a toddler’s life because he or she did not yet weigh 30 pounds or hadn’t grown 3 feet tall. We don’t believe little people are less worthy of life than basketball players or runway models.
In short, no sensible person believes that size alone determines personhood. We do not consider a baby who weighs 4 pounds at birth to be less human than one who weighs 10 pounds. Thus there is no moral difference between killing an unborn baby and killing any other person based on size alone. Next week, we will address the argument that abortion is permissible because of an unborn baby’s level of development.