Development of doctrine

Development of doctrine is a term used by John Henry Newman and other theologians influenced by him to describe the way Catholic teaching has become more detailed and explicit over the centuries, while later statements of doctrine remain consistent with earlier statements.
Newman's Formulation.
The term was introduced in Newman's 1845 book "An Essay on the Development of Christian Doctrine". Newman used the idea of development of doctrine to defend Catholic teaching from attacks by some Anglicans and other Protestants, who saw certain elements in Catholic teaching as corruptions or innovations. He relied on an extensive study of early Church Fathers in tracing the elaboration or development of doctrine which he argued was in some way implicitly present in the Divine Revelation in Sacred Scripture and Tradition which was present from the beginnings of the Church.
He argued that various Catholic doctrines not accepted by Protestants (such as devotion to the Blessed Virgin Mary, or Purgatory) had a developmental history analogous to doctrines that were accepted by Protestants (such as the Trinity or the divinity and humanity of Christ). Such developments were, in his view, the natural and beneficial consequences of reason working on the original revealed truth to draw out consequences that were not obvious at first. This thinking of Newman had a major impact on the Bishops at the Second Vatican Council, and appears in their statement that ″the understanding of the things and words handed down grows, through the contemplation and study of believers, ... (which) tends continually towards the fullness of divine truth."
As distinct from evolution of dogmas.
There is a more radical understanding of development of doctrine that is known as "evolution of dogmas". This view, mixed in with philosophical currents such as vitalism, immanentism and historicism, was at the heart of the modernist controversy during the papacy of Pius X, and was condemned in the encyclical "Pascendi dominici gregis". Although modernist intellectuals such as George Tyrrell and Alfred Loisy did at times cite the influence of Newman's ideas on their thinking, their goal was not so much to understand the ancient roots of Church doctrine but to make it change meaning, according to their own ideas in the liberal spirit of the times.
Protestantism.
Many Protestants, particularly those influenced by Mercersburg Theology, believe in doctrinal development and see the Reformation itself as an example of it. In Philip Schaff's inaugural address as a professor at German Reformed Seminary, he described the Reformation as "the legitimate offspring, the greatest act of the Catholic Church". In addition, the Protestant slogan Semper reformanda implies a form of ongoing doctrinal development.
Eastern Orthodoxy.
Eastern Orthodox theologians reject the concept of doctrinal development outright, instead arguing that the entire deposit of faith has been present in the Church from the very beginning, and has never changed. However, authors such as Daniel Lattier have argued that some older Eastern Orthodox thinkers did not reject the concept outright, and that Eastern Orthodoxy may allow a form of doctrinal development, albeit more limited than Western forms of it.