Immaculate Conception Dogma: Development

Q: What happened in the history of the Church to aid in the development of the Dogma of the Immaculate Conception?

A: A combination of many things shaped the Dogma of the Immaculate Conception:

1) The consciousness of Mary's singular election as Mother of God's Son from early centuries.
2) Linked to this eminent place the realization of her holiness (Panagia) in Eastern tradition.
3) The interpretation of Mary's holiness in regard to original sin: How to explain compatibility? This problematic was proper to Western theology since 11-12 c.
4) A strong popular drive in favor of a perfect, pure human realization of Church in Mary.
5) Identification with post-Reformation Catholic Marian devotion: understood as opposition to Protestantism embodied in the Immaculate, i.e. pure and strong woman representative of God's grace among us.
6) Centuries of theological debate of pros and cons leading to worldwide consultation in favor of the dogmatization.