In the modern abortion debate, the idea that life begins at conception is often dismissed as a purely religious belief by those on the pro-choice side. However, it shouldn’t be. The fact that human life begins at conception is widely accepted within secular science. A survey conducted by Steven Jacobs at the University of Chicago, which included over 5,000 biologists, found that 96% agreed life begins at conception. Notably, the majority of respondents identified as liberal (89%), pro-choice (85%), and non-religious (63%).
Jacobs also conducted a comprehensive literature review of 20 peer-reviewed journals and noted the following:
“Peer-reviewed journals in the biological and life sciences literature have published articles that represent the biological view that a human’s life begins at fertilization (‘the fertilization view’). As those statements are typically offered without explanation or citation, the fertilization view seems to be uncontested by the editors, reviewers, and authors who contribute to scientific journals.”
Why is it, then, that a study surveying liberal, pro-choice, and secular biologists yielded the same conclusion—that life begins at conception— is often dismissed as a religious perspective? Consider this quote from the widely recognized embryology textbook, Developing Human: Clinically Oriented Embryology (7th edition):
“Human life begins at fertilization, the process during which a male gamete or sperm (spermatozoon) unites with a female gamete or oocyte (ovum) to form a single cell called a zygote. This highly specialized, totipotent cell marked the beginning of each of us as a unique individual.” “A zygote is the beginning of a new human being (i.e., an embryo).”
Dr. Micheline M. Mathews-Roth of Harvard Medical School echoed this scientific consensus in her testimony, which referenced over 20 embryology and medical textbooks:
“It is incorrect to say that biological data cannot be decisive… It is scientifically correct to say that an individual human life begins at conception.”
Experts acknowledge this point: at conception, a new, distinct being comes into existence. This new life is different from both the father and mother; it has its own unique DNA. Left to develop, it will one day grow into a fully independent human being. The differences between you now and you as a zygote are size, level of development, environment, and degree of dependence—none of which change the fundamental nature of being human. After all, what else could it be but human? Attempts to downplay this reality by calling it “just an embryo,” “just a zygote,” or more cynically “a clump of cells,” fail to address the fact that these terms represent stages of human development, not different species.
The only plausible criterion that could disqualify it as human might be its level of development. But even a cursory examination of this argument collapses. Ask yourself: “Level of development of what?” The answer, of course, is the level of development of a human, a homo sapien. You don’t become more or less homo sapien as you develop. Humanity is all-or-nothing; you don’t start at 1% human at conception and gradually become 100% human at birth or adulthood.
Imagine applying such a standard: “They’ve developed arms and legs, so now they’re 40% human. Their internal organs have formed, so they’re 70% human. With a functioning brain, they’re now 90% human.” Would we subtract from their humanity if they lost a leg or kidney later in life? If someone were brain-dead, would they be less a member of the species homo sapien? When a person donates their body to science, and their organs and brain are dissected, do they lose their indentification with the human species with each removal? Of course not. A human who has died is simply a dead human, not something else.
Is This Just a Philosophical Question?
One response often given by pro-abortion advocates is that the question of when life begins is purely philosophical, not scientific. Therefore, even if biologists agree that life begins at conception, it supposedly doesn’t carry much weight since it’s a “philosophical question.” While it’s true that philosophy plays a role in this discussion (as philosophy permeates everything), that doesn’t mean science can’t contribute. In fact, both science and philosophy are essential for determining when life begins. Whenever biologists conduct experiments, they rely on principles from the philosophy of science and draw conclusions based on the philosophy of logic.
Furthermore, philosophy cannot address this question without the input of science. Without scientific insights, philosophers wouldn’t know when a distinct organism with unique DNA emerges, when brain activity begins, or when a baby becomes viable outside the womb. Attempting to restrict the question of when human life begins to either science or philosophy alone is futile—both fields are integral.
That said, there’s a compelling reason to prioritize biologists in answering this question. While biologists must be familiar with relevant philosophical concepts, philosophers often lack the necessary biological knowledge. Biology has long studied and debated the question of when life begins. And when even pro-choice biologists readily admit that life begins at conception, it seems reasonable to conclude that the issue is settled—barring any groundbreaking discoveries in the future.
However, there’s a related question that only philosophy can answer: does human life have intrinsic value, and does it deserve legal protection while in the womb? This is a matter philosophy must explore. Remember, the differences between myself, writing this article, and myself as a fertilized egg boil down to size, level of development, environment, and degree of dependence. If your answer is “no,” then you’re essentially claiming that one of these factors determines value or the right to legal protection. That discussion, however, is one I’ll leave for a future article.
Conclusion
The debate about when life begins and its implications will likely continue to provoke intense discussion. Pro-abortion advocates may rely on utilitarian arguments, suggesting that societal outcomes justify permitting abortion, or they may prioritize bodily autonomy over the unborn child’s right to life. These are philosophical positions worthy of debate. However, one position that cannot hold ground, as demonstrated throughout this article, is the claim that life does not begin at conception. The overwhelming consensus from textbooks, peer-reviewed literature, and even pro-choice scientists clearly establishes this fact: human life begins at conception.
This is not a matter of religious dogma but an unambiguous conclusion drawn from biological science. To deny this is to disregard evidence from both the academic and medical communities. What remains to be debated is not when life begins but how society should value and protect it. Whether one’s stance is influenced by philosophy, ethics, or practical considerations, let us at least have the honesty to start from a place grounded in scientific truth.
Human life is a continuum, beginning at conception and developing through various stages that do not diminish or alter its fundamental nature. It is up to society to grapple with the ethical and legal implications of this reality. Whatever side of the debate you fall on, it’s crucial to engage with integrity, informed by science and guided by reason.
Post Note
Below are additional quotes from respected textbooks and scientific literature:
From Human Embryology & Teratology (Ronan R. O’Rahilly, Fabiola Muller [New York: Wiley-Liss, 1996],5-55):
Fertilization is an important landmark because, under ordinary circumstances, a new, genetically distinct human organism is thereby formed.
(Carlson, Bruce M. Patten’s Foundations of Embryology, 6th edition, New York: McGraw-Hill, 1996, p. 3) states:
“Almost all higher animals start their lives from a single cell, the fertilized ovum (zygote)[.] … The time of fertilization represents the starting point in the life history, or ontogeny, of the individual.
“Okada et al., A role for the elongator complex in zygotic paternal genome demethylation, NATURE 463:554 (Jan. 28, 2010):
“The life cycle of mammals begins when a sperm enters an egg.”
Signorelli et al., Kinases, phosphatases and proteases during sperm capacitation, CELL TISSUE RES. 349(3):765 (Mar. 20, 2012):
“Fertilization is the process by which male and female haploid gametes (sperm and egg) unite to produce a genetically distinct individual.
”Coy et al., Roles of the oviduct in mammalian fertilization, REPRODUCTION 144(6):649 (Oct. 1, 2012) (emphasis added):
“The oviduct or Fallopian tube is the anatomical region where every new life begins in mammalian species. After a long journey, the spermatozoa meet the oocyte in the specific site of the oviduct named ampulla, and fertilization takes place.”
Marcello et al., Fertilization, ADV. EXP. BIOL. 757:321 (2013):
“Fertilization – the fusion of gametes to produce a new organism – is the culmination of a multitude of intricately regulated cellular processes.”
Clark Edward and Corliss Patten’s Human Embryology, McGraw – Hill Inc., 30:
“It is the penetration of the ovum by a sperm and the resulting mingling of nuclear material each brings to the union that constitutes the initiation of the life of a new individual.”
The medical textbook, Before We Are Born – Essentials of Embryology and Birth Defects, states:“The zygote and early embryo are living human organisms.”
This is but a partial list from Lifenews and Akleg
Works cited:
Jacobs SA. The Scientific Consensus on When a Human’s Life Begins. Issues Law Med. 2021 Fall;36(2):221-233. PMID: 36629778.
Keith L. Moore, The Developing Human: Clinically Oriented Embryology, 7th edition. Philadelphia, PA: Saunders, 2003. pp. 16, 2.
Expositing Reality 