The development of doctrine takes place as Christ foreshadowed when He proclaimed:
“I will not leave you orphans; I will come to you." (John 14:15-18) “The Advocate, the holy Spirit that the Father will send in my name, he will teach you everything and remind you of all that I told you.” (John 14:26) “But when he comes, the Spirit of truth, he will guide you to all truth. He will not speak on his own, but he will speak what he hears, and will declare to you the things that are coming. He will glorify me, because he will take from what is mine and declare it to you. Everything that the Father has is mine; for this reason I told you that he will take from what is mine and declare it to you.” (John 16:13-15)
Often a dogma or doctrine is infallibly defined after the need is identified through a dispute over what should be believed (faith – the Trinity) or how we should act (morals – contraception).
In Mysterium Ecclesiae, (CDF, 1973, #5): “For this reason also it often happens that ancient dogmatic formulas and others closely connected with them remain living and fruitful in the habitual usage of the Church, but with suitable expository and explanatory additions that maintain and clarify their original meaning. In addition, it has sometimes happened that in this habitual usage of the Church certain of these formulas gave way to new expressions which, proposed and approved by the Sacred Magisterium, presented more clearly or more completely the same meaning.” This was seen in John XXIII”s opening address of Vatican II, using the words of St Vincent of Lerins, and Vatican I – “with the same meaning and the same sense.”
“ ‘Doctrinal development’ is just the name for the process by which the Church reaches certitude that a given proposition, p, states exactly what God has said and hence may be proposed to the faithful as obligatory for belief.” William H Marshner, Reasons For Hope, Christendom College Press 1982, p 177).
The meaning of dogmas is succinctly stated by the great Romano Guardini: “And heresy consists in precisely this – the arbitrary selection of certain aspects of sacred truth. Dogma opposes this tendency, and safeguards the fullness of revelation.” (The Faith And Modern Man, Burns Oates, 1952, p 146).
John Henry Newman writes that the revealed Word of God (or deposit of faith), considered precisely “in itself or objectively” is “in the form of dogma”….the whole Church’s grasp of Christianity is “objective” insofar as it has passed “into dogmas”. (Reasons For Hope, Christendom Press 1982, Ed Jeff Mirus, p 172).