Tractatus de Deo uno secundum naturam

The rational knowledge of the law of nature asserted by the Apostle for the gentiles includes and demonstrates the rational knowledge of God as supreme lawgiver.

« The Apostle Paul clearly teaches that the moral law, absolutely binding, is knowable and known by the gentiles through the powers of reason, without a positive revelation of that same law; and this rational knowledge presupposes and includes in exactly the same way the rational knowability and knowledge of God, without the positive revelation handed down and received concerning the existence of God; although some at least confused knowledge of God is prior in order to the more distinct knowledge of moral obligation. »

The crux of the matter turns on this: that from the teaching of the Apostle, and therefore from the revealed word of God, it is shown that the knowledge of moral obligation, or of the binding law of nature, is possible from the powers of reason, without this knowledge presupposing a positive revelation from which it is drawn or on which it rests. Given this, it follows, or rather is included in this very point, that some knowledge of the existence of God can also be purely rational and not founded on positive revelation; for the knowledge of moral obligation, essentially including some notion of God, cannot come from the powers of reason apart from revelation, unless the notion of God in the same way stands as a foundation essentially included in the very knowledge of moral obligation. Another question, more philosophical than theological, concerns the logical connection between the two kinds of knowledge: whether the knowledge of the law is prior in order, from which one arrives at the notion of God; or whether, on the contrary, the power of reason to know God is concluded only from the revealed power of reason to know the law, because the one cannot be without the other. There are therefore three parts of the thesis.

I. That the rational knowledge of moral principles, which can be, and has been, among the gentiles without a positive revelation of the moral law, Paul teaches at Rom. II. 14–16. The context of the whole passage, vv. 9–16, reads thus. The aim of the Apostle, as elsewhere throughout the whole epistle, and especially in this passage, is to overthrow that Jewish error and pride by which they boasted that it suffices for righteousness to be of the Jewish race and to belong to the Mosaic economy. Cf. Iustin. dialog. cum Tryphone n. 44. 102. 105. As to race, then, the Apostle says, God has no regard for it; but both Jews and Greeks are judged according to their works, whether good or evil, vv. 9–11. If the Jews glory in the privilege of the law and of the Mosaic economy, this will not free them from destruction; nor do they have any reason to lift themselves up proudly above the gentiles, to whom the law has not been revealed. For just as those who sinned without the law will perish, not indeed on account of the transgression of an unknown law, but on account of sins committed against the law, known not from revelation but from elsewhere; so those who belong to the law are not therefore already saved, but on the contrary will be judged according to the revealed law: « for the hearers of the law are not just before God, but the doers of the law will be justified » vv. 12. 13.¹

Paul illustrates this whole doctrine by comparing Jews with gentiles. The difference, he says, is not that those have received the law and are by that very fact sons of righteousness, while these are absolutely without law and as it were a priori destined for ruin; and he proves that this is not so from the fact that the gentiles too have a natural law, according to which they will be judged, vv. 14–16. In this section is contained what we have to prove.

« For when the gentiles, who have not the law, by nature do the things of the law, these, not having the law, are a law to themselves; who show the work of the law written in their hearts, their conscience bearing witness with them, and their thoughts between themselves accusing or even defending, in the day when God will judge the secrets of men according to my gospel through Jesus Christ »².

The law which the gentiles are said not to have is here not the Mosaic ceremonial law; for the gentiles do not by nature do the things of that law, nor do they have them written in their hearts in any sense; but this whole matter evidently pertains to the moral law, as is explicitly declared also in what follows, vv. 18–22, where it is a question of the law forbidding theft, adultery and idolatry. But this law cannot be understood simply and as to the thing itself, insofar as the gentiles are said not to have it; on the contrary, the Apostle explicitly teaches that as to the thing itself this law is written in the hearts of the gentiles. Paul therefore distinguishes the form of the law manifested to the Jews through positive revelation, according to which the gentiles do not have the law, and the thing itself of the law (τα του νομου, το ἐργον του νομου), which the gentiles also have, but through another manifestation. The law positively revealed is called ὁ νομος, but even apart from revelation there become known τα του νομου, το ἐργον του νομου. Therefore the opposition in Paul is not between the law and its denial, but between one mode of manifestation and another: for the Jews it is positive revelation, while for the gentiles positive revelation is denied, and the opposed mode of manifestation is declared to be manifestation through rational nature itself; that is, that apart from positive revelation of the law they understand by the light of reason the moral good and evil, and the obligation to do the one and avoid the other: « by nature (φυσει, rational nature teaching) they do the things of the law; » not having the law, they are a law to themselves; » « they show the work of the law written in their hearts. »

Now I think no one will bring to mind the objection which an anonymous Belgian writer has raised against this doctrine.³. He said that the revelation which Paul denies to the gentiles regarding the law is nothing other than the Mosaic revelation; therefore for the gentiles there is presupposed, or can be presupposed, another positive revelation, namely that made to the first parents and propagated by tradition to all nations, from which they are taught and without which they could not know the moral law. There would therefore be in the Apostle an opposition not between positive revelation for the Jews and its denial for the gentiles, but between one revelation in the Mosaic form and another, primitive, one.

But let us not, I beg, insert our philosophical findings into the text of Paul; rather let it be asked only what the Apostle teaches. Now indeed he not only denies that the gentiles have a revelation of the law; he also distinctly teaches whence they know the moral law, or at least could know it. For to the law which they do not have as revealed (add if you like, revealed through Moses), the Apostle opposes nature: where he clearly assigns to the gentiles, in place of the revelation by which the law was promulgated to the Jews, another principle of knowledge; for in place of the positive revelation of the law (if you like, Mosaic) there is for them nature, and not another revelation in place of the revelation. Paul declares this even more clearly; for when they do by nature the things of the law, « such men, not having the law, are a law to themselves. » As in the first clause nature is substituted for the revelation of the law, so in this second, which is an explanation of the first, the place of the revelation of the law is taken by the rational men themselves. How then can another positive revelation of the law be understood, when the Apostle, in opposition to revelation, even if Mosaic, declares nature to be the promulgator of the law, so that the gentiles themselves are a law to themselves?

The Apostle further explains how they are a law to themselves. Nature, and men themselves as beings of rational nature, are not a law-giving principle, as the Kantian philosophy feigns; rather they are a law to themselves, inasmuch as their rational nature makes the law manifest to them and, as it were, promulgates it. Indeed this promulgation of the law consists in nothing other than the knowledge of obligation through the natural light of reason. The Apostle signifies this in those words: « they are a law to themselves, who show the work of the law⁴ written in their hearts. » Since he has explicitly opposed to the promulgation of the law through revelation nature and men themselves of rational nature, it is easily understood that this writing of the law in the hearts (the intellects) is not that writing by which the law itself, and revealed doctrine through the more abundant inward grace of the New Testament, is said to be written in hearts (Jer. XXXI. 33; Heb. VIII. 10; X. 16); it is rather a writing whose proximate principle is rational nature itself⁵ in opposition to the writing on tablets and to positive revelation.

Further, those who do not have the law show that the law is written in their hearts, or this knowledge of the law, by the fact that their rational thoughts (λογισμοι) accuse evils, and defend and approve goods. That these accusing and defending thoughts did not arise from any revelation of the law, whether Mosaic or other, is clear from the fact that Paul adduces this testimony of conscience to declare the writing of the law in the hearts of the Gentiles. Four clauses are connected to declare the same thing: without a revealed law they naturally do the things of the law; whence it follows that, in place of a revealed law, they are a law to themselves; this is declared by another clause, that they have the law written in their intellects; finally this is made manifest by the testimony of their own conscience, while by rational thoughts within themselves they approve goods and condemn evils.

There are therefore two series of statements. In one of them the revelation of the moral law is affirmed, where we do not deny that the Apostle has before his eyes specifically the Mosaic revelation: « whoever have sinned in the law ... hearers of the law ... you rest in the law ... instructed (κατηχουμενος) by the law ... having the form (μορφωσιν, a clear expression) of knowledge and of truth in the law. » In the other, opposed series, not only is this special Mosaic revelation denied for the Gentiles; but the principle of knowledge is declared in such a way that every positive revelation of the law is excluded from this knowledge of the Gentiles: « the Gentiles who do not have the law naturally do the things of the law ... not having the law, they are a law to themselves ... they show the work of the law written in their hearts ... their conscience bearing witness to them, and their thoughts between themselves accusing or even defending. »

Let it therefore remain wholly settled and fixed that the Apostle teaches not that the faculty of human reason is able to receive and understand the moral law as set forth by positive revelation; but that the power of reason, by its own light, without the proposal of positive revelation, is able to understand moral good and evil, and therefore the moral principles and the absolute obligation of the natural law. Whence Tertullian rightly says (De corona militis, ch. 6) that the law is both natural law and legal nature, that is, that rational nature itself, by its own power, is the teacher of the law. Now whoever by the light of reason understands the obligation to avoid moral evil and to do good, by that very fact understands that this obligation holds for every rational creature, and that it is an absolute obligation, always and everywhere, binding under every hypothesis. Indeed it is understood that no circumstances can be conceived in which the strictest obligation of a rational creature to avoid moral evil would not remain; yet it is not thereby denied that there can be acts which in some circumstances are evil and in other circumstances are not evil, for although materially they are the same, in the moral order they are different according to the diversity of circumstances. Much less, by the rational knowledge of absolute obligation binding under every hypothesis, is signified (as that anonymous writer has indeed wittily interpreted these words of ours and reproached us for them) the breadth of rational knowledge, readily obtainable without revelation in the second act, which extends to the whole moral law and to all the circumstances determining under which moral acts are good or bad.

This knowledge of the law, formally as of the law that absolutely binds, is already included, as I have said, in the very knowledge of moral good and evil. Moreover the Apostle expressly teaches a rational knowledge of the absolutely binding law itself, such that conscience holds some acts to be good, and absolutely condemns others as evil, with approval and condemnation to hold good in the very « day when God shall judge the secrets of men through Jesus Christ »⁶.

II. Now in the knowledge of the morally binding law there is also included at least some confused knowledge of God as the supreme principle and end. For neither can the ultimate reason of this absolute obligation, which man naturally knows, be understood to be the very dignity of human nature, as the Kantians and, from Kantian principles, the Hermesians have wished; since man, through knowledge of his absolute obligation, does not understand his dignity as something that would command, but rather his dependence on some superior, to whom he is bound to be subject and to obey in order to keep right order. And because he understands moral obligation as absolute, to which every rational creature is subject, by that very fact he understands this superior, in whose eminence over all creatures the obligation is founded, at least obscurely and confusedly, as the supreme Lord, to whom absolute obedience is owed. Indeed Paul himself (Rom. I. v. 32) declares that the Gentiles, by the same light of reason by which the invisible things of God are seen as understood from the physical order, have also known the moral order formally as the law of God binding absolutely. For from this their sin is shown: since « when they knew the law of God, that they who do such things are worthy of death, they not only do them, but also consent to those who do them »⁷.

Without doubt, therefore, the Apostle teaches a rational knowledge of the moral order such that there is contained in it at the same time at least a confused knowledge of the existing God, the supreme lawgiver and ultimate end. Now if the knowledge of obligation can be, and in fact is, to some degree, simply through the light of reason without positive revelation, as we have shown the Apostle teaches; the same light of reason, understanding the obligation of the law, necessarily embraces also God as existing, without whom that absolute obligation itself could not be understood. If, however, it were said that the knowledge of God derived from revelation is presupposed as a foundation, so that reason may understand moral obligation; then this knowledge of the law would not be possible without revelation, but would wholly rest of necessity on revelation, against what Paul most plainly teaches. Therefore, from the very fact that it is established from the doctrine of the Apostle that the obligation of the natural law can be understood simply by the light of reason, without revelation being presupposed, it is also established, and included in this same doctrine, that in the same way, by the light of reason, one can arrive at the knowledge of God as the supreme principle of obligation and as lawgiver.

III. The question concerning the logical connection between the knowledge of God and the knowledge of the absolutely binding law is another: whether not only the latter follows from the former, but also, in the reverse order, one can arrive from the latter at the former. For our purpose the solution of this question would not be necessary here, since it is quite sufficient for our purpose that, in the knowledge of the law through the light of reason, as the Apostle declares, there is also included the knowledge of God through the same light of reason without revelation, by whatever means reason can first arrive at this knowledge of God. If nevertheless it should please us to answer the question: first of all, from what has been said it is evident that the knowledge of absolute obligation cannot be presupposed as a foundation from which one arrives at the first knowledge of God, since this knowledge is the foundation of that one; and therefore in the reverse order that first knowledge cannot be attained from the other. Whence also St Paul seems rather to have deduced the natural knowledge of the law and of the moral order from the naturally known existence of God, than to have wished to demonstrate the latter from the former. Yet it does not follow from this that there is no ascent from the knowledge of the moral order and of the law to the knowledge of God. For that middle term, or argument, from the moral order can be proposed in two ways: (1°) in conjunction with other demonstrations of the existence of God; (2°) by itself and absolutely. In the first way, reason can ascend analytically from other manifestations to the knowledge of the existence of God; and, from this known, distinctly understand the absolute obligation of the moral law. From this distinct knowledge there can moreover be made, as it were, a return to confirm and more clearly understand the very existence and perfection of God. In this process no one will say that another circle occurs, except the ascent from creatures to the knowledge of God, and the descent from God to know creatures more perfectly, and from these, at last more perfectly known, the return to God to be more fully understood. Now such a return, which is sufficiently inferred from the Apostle, ought to be judged all the more legitimate and opportune, because clear knowledge of moral obligation does not necessarily presuppose clear and distinct knowledge of the existence of God, although it cannot subsist without some knowledge of Him, at least confused.

If, on the other hand, the argument is considered by itself and separated from the others, it cannot indeed be presupposed that a perfect knowledge of obligation is had without knowledge of God, so that one could first arrive at the latter from the former, as we have already said. But the perfect knowledge of absolute obligation is one thing; another is some knowledge of the moral order taken more broadly. For from the very consideration of rational nature ordered to the true and the good, and from the consideration of human society, the necessity and existence of the moral order are easily understood: the existence of the ultimate end in the enjoyment of the true and the good, the necessity and existence of rights and duties, since these are essential relations of rational nature, which without them would involve a contradiction. But these essential relations, whose necessity and existence are understood, would lack an ultimate foundation, unless there existed the supreme good, a holy and just lawgiver and supreme judge. Therefore, just as from the understood physical order human reason can know God as existing, so from the perceived essential relations of the moral order it can rise to knowing God as the exemplary and efficient cause of the order. Here, indeed, the order of things is objective in itself; yet in practice, and by the very fact, such notions of the moral order—as I shall say elsewhere of the metaphysical notions of true, good, necessary—I judge to be the foundation not of the first knowledge of existence, but of a more refined knowledge of the perfection and attributes of God. Fuller discussion of these matters belongs to philosophy. Cf. Hieronym. in Gal. I. T. VII. p. 391; Chrysost. ad scandalizatos c. 8. T. III. p. 482 ; Constitut. Apost. l. VIII. c. 12.