The Christian tradition
4. Some scholars, considering the prospective benefits to be derived from experimenting on human embryos, have alleged that the Christian tradition had already set a precedent for treating the early human embryo with 'graded status and protection'.3 In support of this it has been noted that there were seventh century books of penance ('Penitentials') which graded the level of penance for abortion according to whether the foetus was 'formed' or 'unformed'. The same distinction was invoked in Roman Catholic canon law which, from 1591 to 1869, imposed excommunication only for the abortion of a 'formed' foetus. Furthermore, St Thomas Aquinas, one of the most authoritative theologians of the Middle Ages, explicitly held that the human embryo did not possess a spiritual soul and was not a human being (homo) until forty days in the case of males or ninety in the case of females.4 Texts from the Fathers of the Church could easily be found to support a similar conclusion.
5. Nevertheless, the contention that for most of Christian history (until 1869) the human embryo has been considered to possess only a relative value -- such as might be outweighed by considerations of the general good -- relies on a misreading of the tradition. Even in the Middle Ages, when most Western Christians held that the early embryo was not yet fully human, it was held that the human embryo should never be attacked deliberately, however extreme the circumstances. To gain the proper historical perspective it is necessary to supply a wider context by incorporating other elements of that tradition.
6. The earliest Christian writings on the issue declared simply, 'you shall not murder a child by abortion'5: the embryo was held to be inviolable at every stage of its existence.6 The first Christian writings to consider the question of when human life began asserted that the spiritual soul was present from conception.7 As one account puts it: 'The Early Church adopted a critical attitude to the widespread practice of abortion and infanticide. It did so on the basis of a belief in the sanctity of human life; a belief which was in turn an expression of its faith in the goodness of creation and of God's particular care for humankind.'8
7. The earliest Church legislation also contains no reference to the distinction of formed and unformed,9 and St Basil the Great, who did consider it, saw it as a sophistical exercise in splitting hairs: 'We do not consider the fine distinction between formed and unformed.'10
8. In the fourth and fifth centuries some theologians argued that human life began at conception,11 some held that the spiritual soul was 'infused' at forty days or so12 (following Aristotle)13 and some held that the timing of the infusion of the soul was a mystery known to God alone.14 However, whatever their views about the precise moment when human life began, all Christians held that abortion was gravely wrong,15 an offense against God the Creator and either the killing of a child, or something very like the killing of a child. If it was not regarded as homicide in the strict sense, 'it was looked upon as anticipated homicide, or interpretive homicide, or homicide in intent, because it involved the destruction of a future man. It was always closely related to homicide.'16