Human personhood.

The terms "individual human life" and "human being" appear throughout Cathleen Kaveny's column. Nowhere, however, do I find the crucial term "human person." The question of when a person exists is essential to considerations of the early stages of human life. In her discussion of Paul Ramsey's view of the "individuated" human life, Kaveny implicitly endorses his argument that there is no "human being" until the time for possible twinning or combination has elapsed. Yet there is certainly a "being," and if not "human," then what? The central issue is not that of human being but of human personhood. This distinction is critical in all rational discussions and decisions involving abortion, "morning-after" pills, human stem-cell research, and related issues.

ELIZABETH McCARTHY DALY 

DeWitt, N.Y.

THE AUTHOR REPLIES:

We need to grapple with three distinct questions. First, at what point does the biological life of a distinct human individual come into existence? This is the question that Ramsey and Grisez tried to address. Both acknowledge that the embryo is genetically human from the time of fertilization, and that it is distinct from the persons whose egg and sperm combined to create it. The point of contention between Ramsey and Grisez is whether the early embryo possesses the requisite stability of individual identity to qualify as a "human being." Grisez says yes, Ramsey says maybe not, because of twinning and combination.

The second question concerns when God infuses a human soul into each developing life. This is the question that Aquinas tried to answer. He concluded that the human soul can only inhabit and animate a human body that manifests a sufficient degree of complexity. Before the point of ensoulment, an embryo or fetus, although biologically an individual human life, would not morally count as a human being. With respect to the question of ensoulment, as Byers suggests, the church counsels erring on the side of caution, because we don't know when the soul is infused. But Ramsey and Grisez are dealing with the prior question: when, biologically, does a new, individual human being come into existence? We have biological evidence to help us evaluate this question, and we must evaluate it as best we can. Appeals to caution do not obviate the need for difficult judgment calls.

The third question is when a new human individual becomes a person. Grisez and Ramsey both say that from the time there is an individual human being, there is a human person meriting our protection. But some philosophers separate the two concepts; Princeton philosopher Peter Singer thinks a human being does not become a person until about the age of one. Unlike Byers, I do not think either Grisez or Ramsey is "muddled." I think both are grappling with difficult issues with integrity and rigor.

CATHLEEN KAVENY