Assessing the moral status of the embryo begins with affirming the moral status of human life in general (4). The principle that human life constitutes the fundamental good serves as the cornerstone of law for our civilization. In no circumstance is the intentional destruction of the life of an innocent individual deemed morally acceptable. This valuing of human life is indeed the moral starting point for both advocates and opponents of CBR, and it flows from the reciprocal respect that we naturally grant as we recognize in the other a being of moral equivalence to ourselves. It leads to the principle of inviolability of human life and the prohibition against using human life instrumentally.
From the perspective of those who object to research that involves destruction of embryos, an evaluation of the moral significance of human life must take into account the full procession of continuity and change that is essential for its development. From this perspective, we must consider how, from conception, our unique genetic endowment organizes and guides the expression of our particular nature in its species and individual character. With regard to fundamental organismal existence (and inviolable moral standing), the act of fertilization is a leap from zero to everything. The gametes, which are properly understood as instrumentalities, parts of the bodies of the parents, are not, in themselves, potential life; they are potential causes of conception. The gametes themselves cease to be; they do not unite in the sense of merely forming a larger composite, but bring into existence a whole new entity, a new human life.
In both character and conduct, the zygote (the one-cell embryo) and subsequent embryonic stages differ from all other cells or tissues of the body; they contain within themselves the organizing principle of the full development of a human being. This is not an abstract or hypothetical potential in the sense of mere possibility. Rather, it is a self-contained potency, an engaged and effective potential-in-process, an activated dynamic of development in the direction of human fullness of being.
Unlike an assembly of parts in which a manufactured product is in no sense present until there is a completed construction, a living being has a continuous unfolding existence that is inseparable from its emerging form. The form is itself a dynamic process rather than a static structure. In biology, the whole (as the unified organismal principle of growth) precedes and produces the parts. It is this implicit whole, with its inherent potency that endows the embryo with its human character and therefore, from this perspective, its inviolable moral status. To interfere in its development is to transgress upon a life in process. The principal of this analysis will apply to any entity that has the potency of a human embryo produced by natural fertilization, regardless of whether it is the product of IVF, cloning or other processes.