FUNDAMENTAL THEOLOGY. — This name is usually given to the entire introductory part of sacred doctrine, in opposition to special theology. But whereas the latter is clearly defined in its object, method, and principle, fundamental theology is still in the process of formation and has not yet attained that definitive structure proper to a science in the modern sense of the word, because it was constituted as a distinct discipline relatively late, beginning in the seventeenth century. This explains the great divergence among authors when it comes to establishing the method, purpose, and above all the object and field of inquiry of fundamental theology. In general, all agree in assigning it the task of proving the fact of Christian Revelation and its infallible preservation in the Roman Catholic Church, and of treating certain preliminary theological questions which, according to very many modern authors, including A. Tanquercy, R. Garrigou-Lagrange, L. Billot, H. Dieckmann, A. C. Cotter, G. Van Noort, J. Brunsmann, C. Mazzella, J. M. Hervé, etc., concern the intimate constitution of the Church and the sources of divine Revelation. It is easy to conclude that fundamental theology, thus conceived, consists of two parts clearly distinct from one another in their purpose and method.
The first part, which comprises the two treatises De vera religione or De vera Ecclesia Christi, is identified with apologetics, whose purpose is precisely to prove, by means of an intellectual demonstration constructed upon historical and rational elements, the divine and revealed origin of the Christian religion (Christian demonstration) and of the Catholic religion (Catholic demonstration). The second part aims to study, in the light of Revelation, the intimate nature of the Church and the sources from which it draws the divine truth that it is authorized to transmit to peoples: Sacred Scripture and tradition. It is clear that in this second part fundamental theology is theology in the strict sense, whereas in the first it is so only in a broad and analogical sense, insofar as this name extends to all those disciplines which have any relation, even a purely extrinsic one, to sacred doctrine and which, in the present university organization, belong to the theological faculty (exegesis, Christian archaeology, liturgy, ecclesiastical history, etc.). The designation
fundamental is derived from the fact that in both parts it establishes the foundation of theology, with the difference, however, that whereas in the first part this foundation is merely extrinsic, like a support that holds up the building from outside without properly belonging to it, in the second it is intrinsic and forms one thing with the building. This is why J. Brunemann defines fundamental theology as «the science which demonstrates and defends, in the light of reason (in the first part, apologetics) and in the light of Revelation (in the second part, theological), the religious foundations of the Catholic faith» (Lehrbuch der Apologetik: I. Religion und Offenbarung, Vienna 1924, p. 1).
Fundamental theology also receives other designations, which are useful to know, not least because they bring to light its different aspects and various functions. It is sometimes called general theology (H. Hutter), because it deals with Revelation in general, considered in its credibility, its organs, and its sources, in contrast with special theology, which studies individual dogmas and individual revealed truths. Others prefer to call it propaedeutics to theology (C. Pesch, J. V. de Groot), or supernatural logic (J. Didio), or even the doctrine of the principles of theology (A. Schill). As for the term apologetics (Al. V. SCHMID, FRANZ, H. Felder), it should be noted that it has too restricted a meaning, since apologetics stands to fundamental theology as the part stands to the whole. Indeed, in addition to apologetics, treated by a purely rational method, fundamental theology includes other questions studied in the light of faith, such as, for example, the dogmatic treatises concerning the intimate constitution of the Church and the sources of divine Revelation. Likewise, the designation fundamental dogmatic theology (A. Tanquerre) seems to us less exact, because it establishes not only the foundations of dogmatic theology but also those of moral theology and of the entire revealed doctrine. For the same reason, the title general dogmatic theology (P. Minges, F. Egger) should be rejected. From this it can also be understood, in order to avoid confusion, why the name fundamental moral theology (T. J. Bouguillon) should not be used to designate the first part of moral doctrine, which deals with human acts, morality, conscience and laws, virtues and sins in general; corresponding to it is special moral theology, which considers laws and obligations, virtues and sins in detail.
The importance and necessity of fundamental theology result from the fact that no dogma could be studied as a revealed truth and deepened by human reason unless it were first accepted by faith and therefore considered in the light of faith. Now this necessarily presupposes a general demonstration of the credibility of Revelation and the use of a special methodology suited to supernatural or revealed truths. The Protestants maintain the contrary, especially F. Schleiermacher, A. Ritschl, K. Barth, and H. Dodwell, whose principal work, first published in 1742, bears the title: Christianity not founded on argument.