I would now like to address several arguments which are commonly raised against the life and humanity of the unborn. See my previous article for arguments that support biological humanity from fertilization.
1) Human life doesn’t begin at fertilization, it began millions of of years ago.
“We are concerned...with what embryo science has to say, ultimately, about the origins of human beings. By this we do not, obviously, mean to ask when the human species, or human life in a generic sense, arose. And so our question is not answered by talk of the continuity of human life through the last few millions of years. We are instead concerned with the origins of individual human beings -- human beings like those reading this book, right now. This is the crucial question: when did those human beings begin to be, and what were the characteristic features of their growth and development?” (Robert P. George and Christopher Tollefsen, Embryo: A Defense of Human Life, Doubleday, 2008, p. 28.)
This is a rather bizarre objection. I’m including it here because I’ve now heard it three times. It’s simply semantic nonsense. A new, unique, genetically distinct human being is created at fertilization (as is attested by the science of embryology). In fact, the quote by O’Rahilly and Muller (see last article) even attests to the fact that life is a continuous process. The mother and father are alive, the sperm and the ovum are alive, and the resulting human organism is alive. Human reproduction is a continuous process of life, this is true. However, fertilization is that critical landmark that establishes the creation of a new, genetically distinct human organism.
2) Viruses and crystals are alive, yet they don't have a right to life.
It is actually not clear whether or not viruses are alive. Louis P. Villareal explains that viruses consist of nucleic acids (DNA or RNA) enclosed in a protein coat that may also shelter viral proteins involved in infection. When a virus enters a cell, it sheds its coat, bares its genes and induces the cell’s own replication machinery to reproduce the intruder’s DNA or RNA and manufacture more viral protein based on the instructions in the viral nucleic acid. Through this process other viruses are replicated. So in a sense, viruses lead "a kind of borrowed life." Viruses seem to more closely resemble a chemistry set than a living thing, so scientists consider them inert chemicals. But whether or not they are alive, it's the differences that matter. Human beings begin life at fertilization and direct their own development, which doesn't end at birth. If it can be said that a newborn is a human being, then there are no grounds to exclude the human zygote from the human community. Even if viruses were alive, it's not simply being alive that makes a human being valuable, but the kind of thing it is.
Secondly, crystals are not alive. They do grow, but they grow through a process called nucleation. In this process, they grow by combining the molecules already present with molecules from other sources, called "solute" molecules. So they are not alive; they do not grow as living organisms grow, through cell division and reproduction.
3) Skin cells/hair follicles/sperm and eggs are human.
A pro-choice advocate who claims that zygotes/embryos/fetuses don’t have a right to life because we would have to give a right to life to cells, sperm, eggs, etc. because they are also human makes the elementary mistake of confusing parts with wholes. The embryo from fertilization is a unique entity that directs its own development from within. Left alone, a skin cell will not develop into a mature human, but that’s exactly what a zygote will do. All of the embryo’s parts work together for the good (survival and flourishing) of the whole organism.
Once the sperm and egg unite, they cease to exist and a brand new human organism exists. It makes no sense to say you were once a sperm or somatic cell. It makes complete sense to say you were once an embryo. The sperm and egg merely contribute genetic material to the creation of a new human organism.
A pro-choice advocate I debated with once claimed that you can’t freeze an adult human, but you can freeze an embryo and it will come back to life, so the embryo cannot be human. This is faulty reasoning. First, embryos can only be frozen up to seven days after fertilization, but the embryonic stage lasts up to two months. After that, it is a fetus. But embryo and fetus are just stages of human development, like infant, toddler, adolescent, teenager, adult, and elderly.
Second, even though a very early embryo can survive the freezing process, it doesn’t follow that they are not human. This just means that early embryos can do one more thing that more mature humans can’t. They can also survive without a heart or a brain (I owe Josh Brahm for this observation via personal correspondence). Consider Han Solo, who was frozen in carbonite in The Empire Strikes Back and later thawed out in Return of the Jedi. Does it follow that Han wasn't human because he was able to be frozen?
When it comes to twinning, it doesn’t follow that because some embryos twin, there wasn’t one whole human organism before that. As Patrick Lee points out, “if we cut a flatworm in half, we get two flatworms.” (Patrick Lee, Abortion and Unborn Human Life, Washington, D.C.: Catholic University Press in America, 1996, p. 93.) However, can you seriously argue that prior to the split, there wasn’t one distinct flatworm? Also, admittedly, we aren’t entirely sure what happens during twinning. Does the original organism die and give rise to two new organisms, or does the original survive and engage in some sort of asexual reproduction? Either way, it does not call into question the fact that there was one distinct organism prior to the splitting.
5) Not all products of conception are human and won’t develop into human beings, and not all human beings may result from conception.
Dr. Bernard Nathanson distinguishes three types of nonhuman entities that result from a union of sperm and egg: the hydatidiform mole (“an entity which is usually just a degenerated placenta and typically has a random number of chromosomes”), the choriocarcinoma (“a conception-cancer resulting from the sperm-egg union is one of gynecology’s most malignant tumors”), and the “blighted ovum” (“a conception with the forty-six chromosomes but which is only a placenta, lacks an embryonic plate, and is always aborted naturally after implantations”). (Bernard Nathanson, Aborting America, New York: Doubleday, 1979, p. 214, as discussed in Francis Beckwith, Defending Life: A Moral and Legal Case Against Abortion Choice, Cambridge University Press: Cambridge, New York, 2007, p. 74.)
As Dr. Beckwith explains in his book, pro-choice advocates often confuse necessary and sufficient conditions. The sperm-egg union is a necessary condition for conception of a human, not a sufficient one. Not everything that arises from the sperm-egg union is a human conception, but a sperm-egg union is necessary for conception of a human.
Conversely, human clones arise without the benefit of conception. Just as the sperm-egg union is a necessary condition for conception and not a sufficient condition, conception itself is a sufficient condition for a human being to come into existence, not a necessary one. (Paraphrased from Francis Beckwith, ibid., pp. 74-75.)
Doctor Maurine Condic also provides a wonderful analogy to show that even though non-human conceptions may occur, it does not follow that all conceptions are non-human:
"Despite an initial (superficial) similarity to embryos, hydatidiform moles do not start out as embryos and later transform into tumors, they are intrinsically tumors from their initiation. Moreover, they are not frustrated embryos that are “trying” (yet unable) to develop normally. Just as a CD recording of “Twinkle, twinkle little star” is not somehow thwarted in its attempt to play the “Alphabet song” by a deficiency of notes in the fourth measure ..., hydatidiform moles are not “blocked” from proceeding along an embryonic path of development by a lack of maternally-imprinted DNA. Rather, hydatidiform moles are manifesting their own inherent properties—the properties of a tumor. Even in the optimal environment for embryonic development (the uterus), hydatidiform moles produce disordered growths, indicating they are not limited by environment, but rather by their own intrinsic nature; a nature that does not rise to the level of an organism...If the necessary structures (molecules, genes etc.) required for development (i.e., an organismal level of organization) do not exist in an entity from the beginning, the entity is intrinsically incapable of being an organism and is therefore not a human being. Such entities are undergoing a cellular process that is fundamentally different from human development and are not human embryos." (Maurine Condic, "A Biological Definition of the Human Embryo," Persons, Moral Worth, and Embryos: A Critical Analysis of Pro-Choice Arguments, as quoted by Jay Watts in his article Condic on the Difference Between Embryonic Humans and Hydatidiform Moles, emphasis Condic's.)
People often point to the high number of miscarriages that occur (many of which are flushed out of the woman’s body). However, how does it follow that just because the woman’s body may miscarry, that the unborn isn’t human? How does it follow that because nature spontaneously aborts unborn humans that we may deliberately kill them? People die of natural causes, but that does not justify murder. Natural disasters (e.g. tornadoes and earthquakes) kill many people at once, but this does not justify nuking cities.
Also, it should be noted that 100% of all humans conceived die. Whether you die as an embryo, a fetus, a teenager, or an adult, why would that affect your status as a human being?
The fact of science is that biological humanity begins at fertilization. None of these arguments work to undermine that basic fact of embryology. The sooner we stop arguing over a question that's essentially been settled by scientists, the sooner we can get to the heart of the matter and keep the conversation focused where it needs to be: in what situations is it ever morally permissible to kill an innocent human being?