Christian scholarship has long defended the idea that human beings have intrinsic value, beginning at conception. However, the new era of embryo-destructive research has challenged such traditional notions.

Excess frozen human embryos from fertility treatments are the target of ongoing research to fill the demand for pluripotent stem cells. Such cells might be transformed into treatments for certain chronic diseases. The fact that such therapies are at least a decade away has not diminished the strong public pressure. There is also an intense demand for other sources of pluripotent stem cells, such as human cloning. One cannot claim that cloning is a different procedure than other methods of producing embryos; the result is identical: a human embryo, capable of implantation.

Traditional Aristotelian-Thomistic arguments favoring personhood of early embryos rely on hylomorphism. Such substance views help to counter secular mereological understandings, where human beings are nothing more than the sum of their individual biological parts.

In this paper, I explore certain vexing moral questions about early human embryos. For example, “conception” itself is composed of two biological processes: fertilization, where sperm and ovum first come into contact, and syngamy, where male and female pro-nuclei unite. Amid these processes, separated by several hours, when does moral status begin? How is that understanding affected by human cloning, where fertilization is absent? How might moral status be affected by altered nuclear transfer, which supposedly creates non-embryonic “biological artifacts,” incapable of implanting into a womb?

Such deep questions are not pedantic, arcane, or irrelevant to modern bioethics. In fact, our answers to these queries will serve as benchmarks for the wider debates on the ethics of reproductive technologies and embryonic stem cell research generally.