Respect for human embryos is often defended on the basis of the potentiality argument: embryos deserve respect because they already possess potentially the features that in adults are fully actualized. Opponents of this argument challenge it by claiming that if embryos should be respected because they are potentially adults, then gametes should be respected because they are potentially embryos. This article rejects this reductio ad absurdum argument by showing that there are two different types of potentiality involved so that the (...) transitivity of potentiality does not hold up in this case. Respect for embryos does not logically entail respect for gametes. (shrink)
In order to understand the nature of human embryos I first distinguish between active and passive potentiality, and then argue that the former is found in human gametes and embryos (even in embryos in vitro that may fail to be implanted) because they all have an indwelling power or capacity to initiate certain changes. Implantation provides necessary conditions for the actualization of that prior, active potentiality. This does not imply that embryos are potential persons that do not deserve the same (...) respect as actual persons. To claim that embryos become persons is to understand the predicate person as a phase sortal, roughly equivalent to adult person. This entails that we would not be essentially persons. In order to explain the traditional understanding of person as a proper sortal rather than a phase sortal, the author distinguishes between proximate and remote potentiality, and shows that, unlike feline embryos, human embryos, by their genetic constitution, possess the remote potentiality to later exercise the typically human activities. It follows that they are already persons essentially. (shrink)
When does a human being begin to exist? Barry Smith and Berit Brogaard have argued that it is possible, through a combination of biological fact and philosophical analysis, to provide a definitive answer to this question. In their view, a human individual begins to exist at gastrulation, i. e. at about sixteen days after fertilization. In this paper we argue that even granting Smith and Brogaard's ontological commitments and biological assumptions, the existence of a human being can be shown to (...) begin much earlier, viz., with fertilization. Their interpretative claim that a zygote divides immediately into two substances and therefore ceases to exist is highly implausible by their own standards, and their factual claim that there is no communication between the blastomeres has to be abandoned in light of recent embryological research. (shrink)
: This paper starts from three assumptions: that we are essentially human organisms, that we start to exist at conception, and that we retain our identity throughout our lives. The identity claim provides the background to argue that it is irrational for a person to claim that it would be impermissible to kill her now but permissible to have killed her at an earlier age. The notion of "full moral status" as an ascertainable property is questioned and shown to be (...) dependent on previously accepted moral norms. It is concluded that the exclusion of the very young from the scope of the norm o f common morality that prohibits the killing of the innocent amounts to discrimination on the basis of age. (shrink)
: This response to Nikolaus Knoepffler's paper in the same issue of the Journal agrees that if the arguments supporting the first two of the eight human embryonic stem cell research policy options discussed are unsound, as Knoepffler argues, then it seems natural to move to the increasingly permissive options. If the arguments are sound, however, then the more permissive options should be rejected. It is argued that three of the rejected arguments, taken together, constitute very good reasons to hold (...) that a human embryo is endowed with dignity from fertilization onward. Thus, countries that want their public policies to match the moral imperative of respect for human beings should refrain from allowing destructive human embryo research and should devote considerable energy and public funds to research and clinical trials using non-embryonic ("adult") stem cells. (shrink)
Gomez-Lobo argues that behind the facade of Socratic irony lies a strictly deductive system of ethics suspended from two axioms--one governing practical rationality and the other specifying the ingredients of the good life. In the _Gorgias_, the author contends, Plato tries to found Socratic ethics on a metaphysical principle about goodness in general, from which the axiom concerning the good life can be derived.
The author argues that individuality does not require indivisibility and that twinning can be explained as the reprogramming of blastomeres that already have begun to differentiate in accordance with the needs of the unified organism that originates at conception.