I have finished reading an excellent article, “John Henry Newman: Mariology and the Scope of Reason in the Modern Age” (Nova et Vetera 11:4 , 993-1016), by Paige E. Hochschild of Mount St. Mary’s University.
The purpose of the article is to apply the argument from “fittingness” (ex convenientia) as found in St. Thomas’ Summa Theologica III, Q1, A1 — and, I would add, in St. Anselm as well — to the doctrine of Mary in the theology of John Henry Newman. It is brilliantly executed. I am obviously a nerd.
In order to explicate the thesis of the article, I would need to replicate the article in full. That is not possible, legally and otherwise. I will, therefore, simply tempt you with excerpts:
The natural world can lead us to a sense of divine handiwork, but this is not the same thing as faith. It is not the role of reason to give rise, by a kind of necessity, to religious conviction; faith is not an effect of sound reasoning. [p. 999]
In more modern terminology, fittingness arguments would consist of inductive arguments that support, but do not compel, a certain conclusion, or, demonstrative arguments in which at least one premise is an agreed upon truth of faith. …Fittingness arguments cannot stand alone; they presuppose a framework that has a claim upon the intellect precisely because it has a compelling character with respect to the imagination, or the illative sense of the whole. 
Faith seeks to understand, not as providing faith with a whole new foundation, but as grounding faith more deeply in the soil of the rational character of the believer. 
…fittingness must show more effectively the internal coherence of the argument of salvation, and the nature of the Church. 
And now in regard to the doctrine of Mary (“mariology”):
If the purpose of the Incarnation is to communicate God’s goodness to the creature, the obstacles to that end must be removed (sin, disobedience, and death), by divine power working through the agency of the creature. …A theological unity comes to light in the parallelism between Christ and Adam, through which Mary can stand in a similar relation to Eve because she is not only mother (of Jesus), but also spiritual spouse, as the creature, reconciled to God, through the trust in God that overturns fear. 
[Mary] is not the mother of his body, or the mother of his humanity merely, but the mother of the person of the Word Incarnate. If we are to take seriously both his divinity and the unity of his person, her relationship to Christ becomes significant in a new light. She truly guarantees and safeguards Christ’s divinity: if she is the theotokos, Christ is “God-with-us” through an effective mediation. 
Christ doesn’t pass through Mary’s womb like a station on his way to Calvary: “the child is like the parent…and this likeness is manifested by her relationship to Him.” 
In Scripture, she is a quiet model of patient and suffering obedience: like John, she is quietly present in faithful devotion…like John, she decreases, very quickly. Likewise in the history of the Church, she is quietly present in the faithful devotion, waiting patiently for the whole Church to affirm her in her right relation to Christ. Newman’s point is that the very way in which Marian doctrine develops over time is itself an illustration of her character: no trumpets and glory, but a quiet witness in the hearts of believers. 
These excerpts do not do justice to the article, but I trust that they are sufficiently stimulating for blogging purposes. The great value of this article is not to convince Protestants of the Catholic doctrine of Mary; rather, it is to convince Protestants that the Catholic doctrine of Mary is not crazy and is perhaps even logical. That is no small accomplishment.
Given that the “argument from fittingness” requires imagination, devotion, and aesthetic perception, I do not expect that most Protestants will even begin to understand.
Image: Basílica de Santa Maria del Mar in Barcelona. August 2015. Photograph is mine.