David S. Oderberg

Transhumanism is the school of thought that advocates the use of technology to enhance the human species, to the point where some supporters consider that a new species altogether could arise. Even some critics think this at least a technological possibility. Some supporters also believe the emergence of a new, improved, superhuman species raises no special ethical questions. Through an examination of the metaphysics of species, and an analysis of the essence of the human species, I argue that the existence of an embodied, genuinely superhuman species is a metaphysical impossibility. Finally, I point out an interesting ethical consideration that this metaphysical truth raises.

The old scholastic principle of the "convertibility" of being and goodness strikes nearly all moderns as either barely comprehensible or plain false. "Convertible" is a term of art meaning "interchangeable" in respect of predication, where the predicates can be exchanged salva veritate albeit not salva sensu: their referents are, as the maxim goes, really the same albeit conceptually different. The principle seems, at first blush, absurd. Did the scholastics literally mean that every being is good? Is that supposed to include a cancer, a malaria parasite, an earthquake that kills millions? If every being is good, then no being is bad—but how can that be? To the contemporary philosophical mind, such bafflement is understandable. It derives from the systematic dismantling of the great scholastic edifice that took place over half a millennium. With the loss of the basic concepts out of which that edifice was built, the space created by those concepts faded out of existence as well. The convertibility principle, like virtually all the other scholastic principles (not all, since some do survive and thrive in analytic philosophy), could not persist in a post-scholastic space wholly alien to it.

This paper re-examines some well-known and commonly accepted arguments for the non-individuality of the embryo, due mainly to the work of John Harris. The first concerns the alleged non-differentiation of the embryoblast from the trophoblast. The second concerns monozygotic twinning and the relevance of the primitive streak. The third concerns the totipotency of the cells of the early embryo. I argue that on a proper analysis of both the empirical facts of embryological development, and the metaphysical importance or otherwise of those facts, all three arguments are found wanting. None of them establishes that the embryo is not an individual human being from the moment of conception.

[About the book] Natural law theory says that humans can only live well if they recognise the goods that are natural for humans, and understand how those goods generate the system of practical guidance that we call morality. Natural law is a long-established and flourishing ethical tradition, with roots in Aristotle and Aquinas, which is increasingly recognised as a worthy competitor to Kantianism, utilitarianism and virtue ethics. The new essays in this collection represent the latest thinking - both constructive and critical - of some of the most important thinkers in the field. And they reflect the growing influence, sophistication, and importance of natural law theory within contemporary ethical debate.

Organisms possess a special unity that biologists have long recognized and that cries out for explanation. Organs and collectives also have their own related kinds of unity, so what distinguishes the unity of the organism? I argue that only substantial form, a central plank of hylemorphic metaphysics, can provide the explanation we need. I set out the idea that whilst organisms possess substantial form, organs abtain the substantial form of the organisms they belong to, and collectives contain the substantial forms of their organismic members. I consider a number of difficult cases, including lichens, biofilms, cellular slime moulds, and plasmodial slime moulds, arguing that none of them pose a serious threat to the threefold distinction between organ, organism, and collective. I conclude by arguing that two prominent, alternative unity principles for organisms do not work, thus giving indirect support to the need for substantial form.