Human life is a precious gift from God. In its very first chapter, the Bible tells us, “God created mankind in his image; in the image of God he created them” (Gen 1:27). Human beings are made in God’s image, which accounts for the surpassing dignity and value of human life. We see that dignity most especially in the spiritual souls with which human beings are endowed, giving them the capacity to know and to love. The Catechism of the Catholic Church puts it this way: “Being in the image of God the human individual possesses the dignity of a person, who is not just something, but someone. He is capable of self-knowledge, of self-possession and of freely giving himself and entering into communion with other persons” (CCC 357). Because human beings are endowed with such dignity, human life is to be respected and protected. This is the basis for the fifth commandment: “You shall not kill” (Ex 20:13). Human life is inviolable. As the Catechism says, “Human life is sacred because from its beginning it involves the creative action of God and it remains forever in a special relationship with the Creator, who is its sole end. God alone is the Lord of life from its beginning until its end: no one can under any circumstance claim for himself the right directly to destroy an innocent human being” (CCC 2258).

The Catholic understanding of the dignity and value of human beings is based on what God has revealed to us in Sacred Scripture and in the living Tradition of the Church. It is also deeply indebted to classical Greek philosophy. The Greek Philosopher Aristotle, in particular, articulates an understanding of human beings as composed of body and soul that is implicit in much of the Church’s theology and in many of her teachings. According to this Christian appropriation of Aristotelian anthropology, human beings, like all living things in this material creation, are composed of soul and body. The soul is the principle that gives unity, shape, and life to the body. The soul makes a thing the individual sort of living thing that it is. Fido the dog, for example, is an individual living dog so long as his dog soul is united with his dog body. Human beings are unique, however, in that they are endowed with spiritual souls by which they can reason intelligently and choose freely, by which they are made able to imitate the knowledge and love of God. The spiritual souls of human beings are also unique in their capacity to remain alive once they are separated from their bodies in the event we call death. Nevertheless, a human being, similar to every other living thing, can be identified when a human soul is united to a human body.

This last consideration is important because, in order to accord to human beings the honor and respect they deserve, we must be able to determine what is and what is not a human being. That is, we need to know when a human soul is united to a human body, in other words, when human life begins and ends.

Determining the precise moment of a human being’s death is difficult. Even deciding on the proper criteria to be used in making this determination is complicated and controversial. Fortunately, determining when human lives begin is easy. Contemporary science makes it clearer than ever that human life begins at conception.

The fact that human life begins at conception, at the moment when the sperm fertilizes the egg and a human zygote is formed with a genetic identity distinct from both parents, is commonly acknowledged. Even the most outspoken proponents of so-called “abortion rights” have long admitted that this is a biological certainty. At the present time, with advancements in embryology and the development of imaging technologies like sonograms, the question of when life begins is not at all difficult to answer and consensus has been reached.

However, the moral questions – the questions about how we treat human beings at the beginning stages of life – are not commonly agreed upon. Consensus on these questions has not been reached. Many people who recognize that human life begins at conception do not conclude that, in their early stages, human lives are inviolable, deserving honor and respect. Despite this lack of agreement in contemporary society, the Catholic Church offers clear answers to many of the moral questions concerning the treatment of human beings at the beginning stages of life. These will be the subjects of future reflections.