It makes a vague appeal to a single sentence from St. Jerome. It looks to be an argument from mere human reason. It's a bit like when someone gives their opinion and then makes a vague appeal to "the science." Such is not a scientific argument; it's merely an opinion with a dash of "science" thrown in for good effect.
That's underselling it by a wide margin. St. Jerome is taken as
representative of patristic thought.
Article IV of the Smalcald Articles, in which the previous quote was taken, begins in this way:
"
That the Pope is not, according to divine law or according to the Word of God the head of all Christendom (for this [name] belongs to One only, whose name is Jesus Christ), but is only the bishop and pastor of the Church at Rome, and of those who voluntarily or through a human creature (that is, a political magistrate) have attached themselves to him, to be Christians, not under him as a lord, but with him as brethren [colleagues] and comrades, as the ancient councils and the age of St. Cyprian show."
The appeal, here, is not to human reason, but to "the ancient councils and the age of St. Cyprian". St. Cyprian is mentioned here, of course, because it was to St. Cyprian that the Roman apologists often made their appeal; Luther in the Smalcald Articles, however, appeals to the ancient councils of the Church and to the historical realities of St. Cyprian's era in which bishops were co-equal brothers, not lords.
Between this opening and the quote offered previously, the Article addresses the fact that the Papacy has no basis in divine command or Scripture, that it is a human contrivance; and that even if the Papacy were to admit this but nevertheless insist that, on the basis of human reason, having a singular universal temporal head of the Church preserves the Church against schism and heretics (and on this point we must admit that this is a point of argument those who seek to make apology for the Papacy often do make) that such reasoning is faulty; for if the Papacy existed merely to facilitate unity, without divine command it could only result in the production of schisms and heretics. And, to take for ourselves historical example, there has never been a shortage of this, with examples myriad:
Of these examples I provide the following:
1) The Western Schism, in which political strife produced, at one point, three competing Pontiffs. Were the Papacy capable of preserving Christian unity because of the universal episcopacy of St. Peter's Chair, then we shouldn't have witnessed the fracture of the Western Church under competing Pontiffs as was the case during the Western Schism.
2) The existence of the Papacy did not stop the existence of heretics or schismatics; for the existence of Lollards, Waldensians, Hussites, and even the myriad of groups which took advantage of the situation of the 16th century demonstrates that the stranglehold of the Papacy over the Western Church produced more factionalism than it ever ceased. The threat of punishment against heretics, further, while capable of causing suffering did not have within its power the ability to maintain Christian unity. Rome's only defense, here, is that all schismatics are heretics--or, in a spirit of charity as has existed since at least Vatican II, that certain schismatics are separated brethren. Nevertheless, the supposed unity which is supposed to flow from the supremacy of St. Peter's Chair has not engendered Christian unity, but has engendered Christian factionalism.
3) We see again, this factionalism stemming from the Roman Pontiff's attempts to accumulate greater power, as occurred at the First Vatican Council, which again resulted not in Christian unity, but in schism; the so-called Old Catholic Churches being example of this.
4) Such supposed unity, again, does not manifest itself as we see in the Sedevacantist movements which have further occurred. And, extending this further into current times the Pontificate of Francis I seems rife with controversy, and whether schism is eminent or not remains to be seen.
Thus the Smalcald Articles assessment that even were we to permit the argument that the Roman Pontiff serves to create Christian unity, the historical evidence is to the contrary. The Papacy has not been a source of Christian unity, but has continually been a source of Christian disunity. And this has been the case, at least, since the time of the Great Schism of 1054.
Of course, the ancient Church in her great wisdom never permitted that a single individual act as head of the whole Church on earth; which is why the Canons do not permit such a scenario from taking place; and why St. Gregory the Great himself rebuked the claims of Cyriacus II of Constantinople.
When the Smalcald Articles, and the other parts of the Lutheran Confessions, rebukes the Papacy it is on the basis of biblical and patristic merit; not a mere polemic; but grounded in the great wisdom and teaching of the Church Catholic; which Rome under the Papacy is rebelling against.
-CryptoLutheran