Dei Filius IV:On the Development of Dogma Andrew Meszaros Introduction Historically, it is indisputable that the intention of the latter part of chapter 4 of Dei Filius was to restate the substantial immutability of the deposit of faith, not for the sake of rejecting doctrinal development, but for the sake of establishing parameters for a certain profectus fidei—progress or development in the faith—which no Catholic theologian doubted, not even nineteenth-century neo-Scholastics. Then-contemporary (e.g., John Henry Newman and the Tübingen school) and subsequent (e.g., Yves Congar and Henri de Lubac) theologians' theories that were more thoroughly worked out presupposed this immutability. The argument here is simple: Dei Filius's teaching on the immutability of dogma not only did serve as the necessary foundation for any sound (i.e., Catholic) theory of doctrinal development, but continues to do so. While the teaching of Dei Filius itself is limited and incomplete, it is essential. Furthermore, its key feature of dogmatic immutability is not compromised by even the most dramatic of doctrinal developments. To establish the ongoing relevance of Dei Filius for contemporary discussions on doctrinal development, I will first draw out certain key similarities between the nineteenth-century, modernist, and contemporary contexts. This will be followed by a presentation of the relevant portions of Dei Filius. Finally, in the longest section, I will discuss what is at stake in the teaching of Dei Filius and offer some different examples of how doctrines develop in ways that uphold the fundamental-theological principle laid out [End Page 909] in Dei Filius: namely, that all doctrinal development is homogenous with, or in continuity with, the deposit of faith. Anton Günther and Theology Today We can identify two major factors that led to the Vatican Council having to address dogmatic development. The first, and perhaps most important, factor is the implication that Anton Günther's (1783–1863) understanding of faith and reason had on dogma and its immutability. The second factor is simply the fact that, in the midst of these pervasive philosophical and theological disputes over faith and reason, Pius IX not only managed to define the Immaculate Conception as dogma, but did so by papal definition: the 1854 definition was the freshest example of what would later be defined in 1870.1 A brief examination of the thought of Günther will help us better understand why the paragraph on development (i.e., the immutability and progress of dogma) pertains to the faith–reason relationship and, hence, appears in the fourth chapter. 2 Günther's major concern is a noble one: namely, to respond to the Kantian critique of supernatural religion. To do so, he sees it as necessary not only to defend rationally but also to explain rationally—according to the philosophical systems of Schelling and Hegel—Christian dogma. Günther is no brash and pure rationalist. He believes in the history of supernatural revelation. He acknowledges that reason alone could never discover supernaturally revealed truths; but, as a so-called semi-rationalist, he believes that, once made known to it, reason can then penetrate and, indeed, prove these revealed truths.3 [End Page 910] But if revealed mysteries are discoverable by human reason, then those same mysteries have to be interpreted in such a way that is, indeed, within the reach of reason using its proper resources.4 Not Scholasticism but German idealism—especially its category of self-consciousness—was Günther's vehicle for giving an account of the faith. Such a re-interpretation of Christian dogma according idealism's categories naturally alters the original understanding of that dogma. But for Günther, this reinterpretation is necessary if revelation is to be accessible to reason. So, for example, because modern psychology cannot make sense of a distinction between "person" and "nature" that is not coterminous, we must conclude, against Ephesus, that Christ is in fact a unity of two persons. Nor, for that matter, is the human person a composite of body and soul as defined by the Council of Vienne (1311–1312). Because God is self-conscious spirit, there is a process of trebling in God that tends toward...