Public opinion on abortion, unlike other hot social issues, has changed very little over the last 30 years. According to both Pew and Gallup surveys, most Americans think abortion should be legal under some but not all circumstances. However, a hard core of 20-30% believe it should be legal in every case, and 12-22% believe it should never be legal.
We must distinguish between abortion as a moral and as a legal/political issue. A person may be morally opposed to abortion and still accept its legality under the 1973 Roe v Wade decision. The United States is a pluralistic democracy that includes people with different moral codes. We should hesitate to use the coercive power of government to enforce a moral belief rejected by a broad sector of the American people.
The number of abortions in 2014 was 926,200, much less than the 1990 peak of 1.6 million. However, for people who see abortion as the moral equivalent of infanticide or murder, this number represents an ongoing holocaust, and Roe v Wade was an abomination.
The strictest proponent of this view is the Catholic Church: "Human life must be respected and protected absolutely from the moment of conception. From the first moment of his existence, a human being must be recognized as having the rights of a person..." (CATECHISM OF THE CATHOLIC CHURCH, article 2270). Conservative Christian groups such as evangelicals and Southern Baptists are nearly as strict, but (inconsistently) make allowance for saving a mother's life or for rape or incest.
The opposite extreme is argued eloquently by The Nation columnist Katha Pollitt in her 2014 book Pro: Reclaiming Abortion Rights. She criticizes the apologetic tone adopted recently by abortion supporters, contrasting it with "the 1970s, when activists proudly defended 'abortion on demand and without apology'." She rejects as a patriarchal relic and an affront to human dignity any law that seeks to control a woman's body through her reproductive system.
Pollitt claims that even if we grant personhood to a fetus, a law requiring a pregnant woman to continue her pregnancy in order to keep the fetal person alive would be like a law making a mother donate her kidney to her child if that were the only way to keep the child alive. But a supporter of the Catholic position would say this is a weak analogy because abortion is a direct act of killing a (fetal) person, unlike the refusal to donate a kidney.
Here we need to look more closely at the concept of a person. Personhood signifies membership in a legal or moral community, which implies the ability to participate in that community. This in turn requires the ability to be conscious of an obligation (legal or moral) and act according to it. That's why, although we think of pets as family, we don't regard them as legally or morally guilty of their misbehaviors. However beloved, they just aren't persons.
Personhood confers not only membership, but also a special kind of value, one that is intrinsic, unconditional and equal in all persons. This is the value that our founders pointed to when they said in the Declaration of Independence: "We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights...." The words "respect" and "dignity" are often used to express recognition of this value.
Adherents of the extreme positions on abortion seem to believe that personhood is an all-or-nothing attribute. However, the capacity for membership in the moral or legal community is not fully developed in children--for instance, we don't expect 5-year-olds to have a full consciousness of moral or legal obligation. From birth to late adolescence, they gradually acquire the full capacity for functioning as persons, and with it the full measure of respect and dignity appropriate to adults (equally). Adults are rightly insulted when treated as children.
As extreme "pro-life" advocates point out, there is a continuous process of development from conception to adulthood. There is no yawning gap from moment to moment in the development from embryo to fetus to infant, juvenile and adult that would present a radical transition from zero personhood to being a person. Extreme pro-lifers want to see this seamless developmental continuity as a slippery slope: unless we recognize a newly conceived single-celled human "as having the rights of a person," we end up justifying infanticide and murder.
However, babies don't have many of the rights of persons. Adult parents carry them around, limit their mobility and make all kinds of decisions for them. Babies are nevertheless members of the community because (unlike fetuses) they are rapidly developing conscious personhood through interaction with other members, especially adults, a process that can't begin until birth. As nearly actual persons they are different from anything else except adult persons, and are valued accordingly.
There is nothing inconsistent in according greater rights to these nearly actual persons than to a human being not yet able to be part of the community. All the more so when this human being can exist only inside the body of the mother, often an adult with full rights.
The advocates of "abortion on demand without apology" make the same all-or-nothing error as their extreme opponents. They want to believe that the killing of a late-term fetus is no more regrettable than killing the single-celled beginning of a human life. They ignore the greater reality of personhood in a late-term fetus compared to an embryo, a reality not yet fully actual, nor as actual as in a baby, but nevertheless much greater than in an embryo.
Surely it is reasonable to claim that it's worse to kill a late-term fetus than to kill an embryo, so that the reason for a late-term abortion should be much stronger than in early pregnancy. A late-term abortion may be necessary sometimes, but it can't be dismissed as merely an episode in a woman's reproductive health-care history.