Among non-Catholic Christians, a common misunderstanding about the doctrine of the Immaculate Conception is that it is the doctrine that Mary miraculously conceived Christ in her womb whilst still remaining a virgin. What the doctrine of the Immaculate Conception is actually about is the conception of Mary in her mother’s womb – the fact that we celebrate the Immaculate Conception on December 8 and celebrate Mary’s birthday exactly nine months later on September 8 is a bit of a giveaway.
But even once this misunderstanding is cleared up, there still remains the question of how we are to understand Mary’s conception and the nature of her sinlessness over the centuries this has led to much theological debate.
There is evidence that the eastern Church celebrated Mary’s conception from the late seventh century, and by the early 11th century it was also being celebrated in the west. But some theologians found it difficult to justify this celebration, for it suggested that Mary was conceived free from Original Sin, that state of non-orderedness to God’s grace. Among these theologians was St Thomas Aquinas.
Aquinas had two difficulties. First, he feared that if Mary had been conceived without Original Sin, then she wouldn’t be in need of redemption, and this would be heretical, since every human person is in need of redemption. However, Blessed John Duns Scotus successfully answered this difficulty by arguing that by being preserved from even contracting Original Sin, Mary had been perfectly redeemed in anticipation of the merits of Christ’s passion.
The second difficulty for Aquinas was of a more scientific nature. Following Aristotle, Aquinas believed that in human generation, there was a first moment of conception when the male and female elements were combined to form an embryo. However, the embryo thus formed didn’t possess a rational soul and so wasn’t a human person. The infusion of the rational soul only took place around 40 days after conception in the case of boys and 90 days in the case of girls. Therefore, since the embryo wasn’t initially a human person, it couldn’t be a subject of Original Sin, so it made no sense to speak of such an embryo as being preserved from Original Sin.
Some theologians attempted to resolve this issue by speaking of two conceptions, the active conception when the embryo first comes into existence, and the passive conception when the embryo is infused with a rational soul. One could then claim that the Immaculate Conception was a doctrine about Mary’s passive conception. This thesis however didn’t sit easily with the Immaculate Conception being celebrated exactly nine months before Mary’s birthday, which would make it correspond to the moment of active conception.
But another way to resolve this issue was to reject Aristotle’s theory, and instead say that when the human embryo first comes into existence, it is infused with a rational soul. This was the view held by Scotus, and it was this view that Pope Pius IX upheld in the 1854 document Ineffabilis Deus, where explicitly defined the doctrine of the Immaculate Conception as follows: “The most Blessed Virgin Mary… in the first instance of her concep-tion, by a singular grace and privilege granted by Almighty God, in view of the merits of Je-sus Christ, the Saviour of the human race, was preserved free from all stain of Original Sin.”
In the same document, the pope was highly critical of those who made a distinction between a first moment of conception and a second moment of conception, and in 1869 the pope abolished the canonical distinction between formed and unformed embryos with the implication that every human life begins at a unitary moment of conception.
Still, the pope’s pronouncements haven’t stopped scientists and philosophers from questioning whether a single-celled embryo could be a human person. There are still a few defenders of Aquinas’s theory of human generation, but they tend to be rather selective of what parts of his theory they accept. According to Aquinas, the female only provided the matter, whereas the male seed possessed a formative power by which it formed the embryo under the active agency of the sun.
But once one accepts modern biology and rejects Aquinas’s medieval science, then one should accept that a single-celled human embryo is a living organism that has all the intrinsic principles it needs to grow and develop into an adult and is hence the same living organism as the adult, that is to say, it is a human person.
Those who wish to deny the personhood of the human embryo will undoubtedly put forward their counterarguments, but it is comforting to know that we have an advocate in Mary, who through her Immaculate Conception defends the sanctity of every human life.
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