The Immaculate Conception of Mary

Some people have claimed it was necessary because if Mary was a sinner, then Jesus could not have been conceived without sin. The immaculate conception may have been necessary for an incarnation involving pregnancy as God would never put a woman in a position where there is even a slight chance she is only saying yes to the pregnancy. But this argument has caused me to rethink that assumption. There is a long tradition of Christian reflection on Mary's consent and hers is consent to be impregnated.