Apologists sometimes maintain that when such doctrines have at last been defined they represent not an addition to the creed but merely a ‘development’ of it. Revealed truth was not at first understood, and hence lay unrecognised for generations before the interpreters gathered its true sense. ‘Finally scrutinizing with fresh care the deposit of revelation, they there discovered the pious opinion, hitherto concealed, as far as they were concerned, in the more general formula, and, not satisfied to hold it as true, they declared it revealed.’30 The best known defence of this theory is Newman's Essay on the Development of Christian Doctrine. Newman wanted to believe that all the teachings now held by the church to be essential were included in the deposit of faith given to the Apostles and espoused by the fathers. When he came to examine the writings of these persons, however, it became plain to him that over and over again—on purgatory, on the adoration of the Virgin, on transubstantiation, on the books to be accepted as inspired, even on the Trinity—the convictions of the early writers were not those of the present church. ‘There are three great theological authors of the Ante-nicene centuries,’ he noted, ‘Tertullian, Origen, and, we may add, Eusebius, though he lived some way into the fourth. Tertullian is heterodox on the doctrine of our Lord's divinity, and, indeed, ultimately fell altogether into heresy or schism; Origen is, at the very least, suspected, and must be defended and explained rather than cited as a witness of orthodoxy; and Eusebius was a Semi-Arian.’31 Such discoveries were deeply disturbing. The question of immediate importance, however, was not whether the fathers agreed among themselves—they did not—but whether the dogmas now held by the church had been held by the fathers at all. Here the idea of development seemed to provide a saving bridge. The oak is not identical with the acorn, yet as a development of it is in some sense the same. The green shoot and the ripened wheat, the child and the man, are not the same, yet we do call them the same. May we not continue to say that the present creed of the church, different as it is from that of the primitive church, is still the same in the sense of being a continuous development from it?

Between the two Vatican Councils there has been a singular change in the Catholic estimation of the essay and its author. At the first Council he was considered by Monsignor Talbot, the English private secretary to the Pope, as ‘the most dangerous man in England’. At the second, his theory was appealed to as a valuable support by ‘the new theologians’; indeed his spirit, according to one observer, Christopher Hollis, seemed to dominate the proceedings. But the famous essay does not give a very firm base for the doctrine of the unity of the church.

For (1) what it does is not so much to explain that unity as to explain it away. If all we mean, for example, by asserting a recognition of the Pope's authority from the first is that the gradual concentration of power in his hands was a natural development from the position and organisation of the early church, then the original meaning of ‘unity’ has disappeared. Such unity would not preclude our holding that neither the authority nor the belief in it was present in the early church at all. As C. D. Broad has said: ‘You have no right whatever to say that the end is just the beginning in disguise if, on inspecting the end as carefully and fairly as you can, you do not detect the characteristics of the beginning in it and do detect characteristics which were not present in the beginning’

(2) The theory therefore tends to nullify the dogma of infallibility. How can one hold that any doctrine warranted by the church at a given time is true until one sees the riper form into which it will develop? If the primacy of Peter was potentially present and infallibly true in the minds of persons who did not suspect its being there and even supposed they meant the opposite; and if, when the church now promulgates an infallible truth, its real meaning is as remote from our present sense of it as the present meaning of Roman primacy is from that of the primitive church, then what exactly is it that at a given time is to be taken as infallible? We cannot certainly know, and what we accept as infallible truth may be a mistake.

(3) The theory is bound to end in question-begging or self-refutation. If, for example, only those dogmas are selected as true developments that belong to the Catholic branch of the church, as opposed to those of the Greek and Anglican branches, which have grown from the same trunk, one will hardly convince these other branches that no parti pris has entered in. On the other hand, if the teachings of these other branches are also accepted as true ‘developments’, some of them, e.g. the denial of Roman primacy, will cancel those of the Catholic line, and then a genuine ‘development’ of the primitive creed may be false. The theory is unsatisfactory in either case.