The Ontological Status of Pre-implantation Embryos

Abstract

Contemporary embryology indicates that the moment of fertilization gives rise to a discrete human organism within a relatively short time-frame. Yet, it is difficult to determine the precise ontological status of the early conceptus. Biological data alone can neither reveal the metaphysical status of nascent human beings, nor does it denote the ethical implications of their organismal identity. One must not confuse biological, metaphysical and moral categories, but rather differentiate between the ontological identity and the moral status of embryos. A challenge for determining the ontological status of the pre-implantation embryo is the possibility of twinning or organismal division, or the recombination of twins to form a chimera. Whether monozygotic or embryonic twinning is due to external factors or is determined intrinsically at fertilization is unclear. Even the influence of epigenetic factors during development, which is sometimes cited as evidence of the incomplete nature of the embryo, presupposes a certain ontological identity. Additionally, the identity of the zygote, morula, and blastocyst embraces a potentiality that eventuates in embodied personhood, provided no extrinsic factors alter normal biological development. This requires the use of philosophical arguments to distinguish the power-to-produce from the power-to-become a psychologically mature and active social “person.” For all intents and purposes, there is a biological continuum stretching from the single-celled zygote to the infant human being. This ontological continuity seems to insinuate that the pre-implantation embryo is a viable human being that deserves the protection accorded to members of the genus Homo sapiens.