In the previous post I explain some of the definitions St. John Henry Newman gives to doctrine, authority, and private judgement. Now I will seek to explore how Newman uses these definitions to construct a view of theology that can be said to “develop” without changing what Christ taught.
First, there exists the issue of when private judgement fails to attain truth. Since private judgement varies from person to person, there are different degrees to which the statements of private judgement can claim to represent truth. Laurence Richardson writes that although private judgement pertains to the individual’s mind, it is always rooted in objective reality.  Private judgement is not identical to one’s personal wish or preference, but is dependent on an external reality that informs it.  Religions rooted in private judgement are referred to by Newman as natural religions. These natural religions, Newman continues, can achieve a level of knowledge of the divine through revelation expressed in nature. Through the basic revelations that exist in all cultures, the greatest people in these cultures can come close to an idea of doctrine. Yet, private judgement alone is not sufficient in and of itself. In his second sermon at Oxford, Newman writes that private judgement points “in a certain direction as a witness for the real moral locality (so to speak,) of the unseen God, yet, as it cannot prove its own moral authority, it afforded no argument for a governor – and judge distinct from the moral system itself.”  The weakness of private judgement is the same of natural religion – there is no authority by which falsity can be teased out. Without authority, private judgement is prone to subjectivist tendencies—tendencies that take the role of religion out of public life. Newman is concerned with the privatization of religion in his own time and gives his sermons to combat the fallacies caused by private judgement gone awry. Newman retains private judgement because it exists as our only connection to the divine and can bring those without revelation to vast knowledge of the divine. However, the safest path to God, for Newman, is to measure your private judgement against the authority of the Church to determine its merit.
Newman is careful not to place complete trust in authority, despite its significance to him. While the failure of private judgement is that there is no mechanism to navigate a vague concept of the divine into a concrete statement that is rooted in reality, the weakness of authority is the struggle of finding the proper authority and the danger of rationalizing God. I have already touched on the problem of finding the proper authority earlier in this essay. Borsch argues that Newman believed that true authority must be one with divine and not human origin. Newman eventually came to regard true authority as the Catholic Church. 
The next problem Newman addresses in his sermon “On the Development of Religious Doctrine” is that of the rationalization of the Divine. In response to the claim that humans are too low a creature to fully understand God, Newman writes, “let, then, the Catholic dogmas, as such, be freely admitted to convey no true idea of Almighty God, but only an earthly one… for what is short of truth in the letter may be to them [children] the most perfect truth, that is, the nearest approach to truth, compatible with their condition”.  The resolution of this problem: to accept our earthly knowledge of truth as a child accepts a less complete explanation of truth than they are capable of understanding. Pragmatically, authority should be cautious of presuming it is capable of completely reducing God to avoid this second problem. According to Newman then, in spite of these problems of authority, the proper authority with a cautious attitude would be in prime condition for the development of doctrine.
Throughout this essay, I have established that Newman believed the development of doctrine is initiated by the reception of revelation by private judgement and subject to the scrutiny of reason under the proper authority of the Apostolic Church. However, a possible counterargument can find basis in Newman’s famous toast, “I shall drink – to the Pope, if you please, – still, to Conscience first and to the Pope afterwards.”  This quote, along with Newman’s uneasy relationship with Rome, counteracts my thesis: authority overrides private judgment – or conscience. While Newman had some issues with the Pope and Church hierarchy of his time, his personal issues with them do not undermine his belief in the authority of the Church. He writes that theological dogmas are “propositions expressive of the judgements which the mind forms, or the impressions which it receives, of Revealed Truth.” 
Doctrine, as described earlier, is formed by the taking of impressions received extrinsically and then privately judging them into sentences and statements of belief, which are approved by an authority. Without private judgement, our ability to transform experiences of revelation into concrete statements or creeds would be impossible. Without authority, however, the entire process falls apart and private judgement becomes too susceptible to emotions or rationalism. Newman’s own conversion from the Anglican Church to the Catholic Church hinged upon his search for the proper authority of Christian truth. While private judgement is necessary for doctrine, authority guards against heresy and false understandings of revelation. This opinion is demonstrated consistently within Newman’s own sermon and in Newman’s defense of his conversion. Left alone, private judgement segregates religious creed to the subjective. Newman argues that authority creates religious doctrine that is not meant for the private sphere—rather, it creates doctrine that contains objective historical truth about the divine that is maintained by the proper authority.
 Richardson, Laurence. Newman’s Approach to Knowledge. Pg 51.
 Ratzinger, Joseph Cardinal. Conscience and Truth
 Newman, John Henry. Fifteen Sermons Preached before the University of Oxford. Pg 23.
 Borsch, Frederick. Ye Shall be Holy: Reflections on the Spirituality of the Early Years of the Oxford Movement. Pg 355.
 Newman, John Henry. Fifteen Sermons Preached before the University of Oxford. Pg 340 and 341 respectively.
 Cornwell, John. The Papal Hijacking of Cardinal Newman.
 Newman, John Henry. Fifteen Sermons Preached before the University of Oxford. Pg 320.