Section 2: The Moral Law of Nature

1. DEFINITION. —By the moral law of nature (lex moralis naturalis) is understood the sum-total of those ethical precepts which God has implanted in the rational nature of man. It is that law which St. Paul says is "written in the hearts" of men,¹ in order to enable them to attain their natural destiny as free beings,² capable of doing right or wrong.

¹ Rom. II, 15. —Cfr. Pohle-Preuss, God: His Knowability, Essence, Attributes, pp. 18 sqq. —St. Augustine, De Div. Quaest., 83, qu. 33, 2: "The natural law has been, as it were, transcribed into the rational soul, so that in the conduct of this life and in earthly customs men may preserve images of such distributions." (Migne, P. L., XL, 36). —IDEM, Epist., CLVII (a/. 89), n. 15: "There is also a law in the reason of man, who uses the judgment of liberty, naturally written in the heart, by which it is suggested that each person should not do to another what he himself does not wish to suffer." (P. L., XXXIII, 681).

² Cfr. St. Thomas, Summa Theol., 1a 2ae, qu. 91, art. 2: "The natural law is nothing other than the participation of the eternal law in a rational creature." —Ibid., qu. 93, art. 1: "The eternal law is nothing other than the reason of divine wisdom insofar as it directs all acts and movements."

The moral law of nature is promulgated by reason.

The content or object of this law are the general conditions under which man lives as an ethical being, especially his relations to God, to himself, and to his fellowmen.³

³ Rom. I, 18-25; Tob. IV, 16; Matth. VII, 12.

Though present from the beginning, the moral law of nature at first manifests itself but vaguely in human reason, but with the growth of that faculty the concept of law and its obligatory force is more clearly and fully brought home to the individual.

2. EXISTENCE. —The existence of the moral law of nature can be proved from the Old and the New Testament.

It is of this natural law, above all others, that Jehovah says: "This commandment that I command thee this day is not above thee, nor far off from thee. Nor is it in heaven, that thou shouldst say: Which of us can go up to heaven to bring it unto us, and we may hear and fulfil it in work? Nor is it beyond the sea: that thou mayest excuse thyself, and say: Which of us can cross the sea, and bring it unto us: that we may hear, and do that which is commanded? But the word is very nigh unto thee, in thy mouth and in thy heart, that thou mayest do it." ⁴ More definite is the teaching of St. Paul, who says: "For when the gentiles, who have not the [positive divine] law, do by nature those things that are of the law; these having not the law [i. e., the positive law] are a law to themselves: who shew the work [i. e., substance] of the law written in their hearts, their conscience bearing witness to them, and their thoughts between themselves, accusing, or also defending one another." ⁵ Therefore, though the positive law of God had not been revealed to the gentiles, they knew and observed its essence in the Decalogue. The law was implanted in their very nature and revealed itself to them.

⁴ Deut. XXX, 1-14; cfr. Jer. XXI, 31-33; Wisd. IV, 20; Matth. VII, 12.

⁵ Rom. II, 14-15. —Cfr. Th. Simar, Theologie des hl. Paulus, 2nd ed., pp. 80 sqq.; J. Quirmbach, Die Lehre des hl. Paulus von der natürlichen Gotteserkenntnis und dem natürlichen Sittengesetz, Freiburg 1906, pp. 60 sqq.

The existence of the moral law of nature is attested by human consciousness. Cicero says that the natural law is co-eval with the divine intellect, and that all men are imbued with it.⁶ Ecclesiastical Tradition on the subject is so constant and uniform that there is no need of developing it.⁷

⁶ De Legibus, II, 4: "It arose together with the divine mind. Therefore the true and sovereign law, fitted for commanding and forbidding, is the right reason of supreme Jove." Cfr. Pro Milone, 10: "It is an unwritten, inborn law for which we were not taught but made, not instructed but imbued."

⁷ On the teaching of Clement of Alexandria and Origen see the monographs of W. Capitaine, Die Moral des Klemens v. Alexandrien, Paderborn 1903, pp. 225 sqq., and De Origenis Ethica, Münster 1898, pp. 76 sqq. —St. Ambrose says (De Abraham, II, c. 11, n. 98): "Let [the wise man] know nothing except to live according to nature, in whose institution and order is the law of God." (Migne, P. L., XIV, 500). —IDEM, De Fuga Saec., c. 3, n. 15: "The law is twofold, natural and written: the natural law in the heart, the written law on tablets." (P. L., XIV, 577). — IDEM, Epist., 73, n. 2-3: "The Apostle also teaches that there is a natural law in our hearts, for he wrote that often 'the Gentiles naturally do the things that are of the law,' and so forth. That law therefore is not written but is inborn; it is not acquired by any lesson, but is expressed in individuals from a certain overflowing fountain of nature and is drawn in by human minds. " (P. L., XVI, 1251). —On the teaching of St. Augustine, who treats of the natural law very exhaustively in different parts of his writings, see H. Oberrauch, De Lege Dei Aeterna ad Mentem S. Augustini, Innsbruck 1776, pp. 14 sqq. —The Catechism of the Council of Trent (III, c. 1, qu. 3) says: "There is no one who does not perceive that a law has been implanted in his soul by God." —Pius IX, in his Encyclical Letter of Aug. 10, 1863, declares: "The natural law has been engraved by God upon the hearts of all."

God Himself is the author of the moral law of nature. The organ of the natural revelation through which He promulgates it, is human reason.

Reason, therefore, is not the author of law.⁸ Reason is not autonomous; it cannot make laws independently of God,⁹ but is merely the organ through which the Supreme Lawgiver proclaims His will.¹⁰ It was in this sense that St. Augustine called the moral law of nature "the law of reason which not even iniquity itself is able to destroy."¹¹ u The sum-total of the ordinances contained in the moral law of nature is often called ''the natural law." ¹² The existence of a natural law in this sense is admitted by all Catholic philosophers and theologians. But there is a controversy regarding the question whether the natural law embodies practicable rules for all the social relations of men, binding them prior to and outside of positive, especially human, legislation.¹³

⁸ Cfr. St. Thomas, Summa Theol., 1a 2ae, qu. 91, art. 3, ad 2: "Human reason in itself is not the rule of morals, but the principles naturally implanted in it are certain general rules and measures of all the things that are to be done by man." — The Syllabus of Pius IX condemns the following assertion (prop. 3): "Human reason, without any regard whatever for God, is the sole arbiter of truth and falsehood, of good and evil; it is a law to itself and by its natural powers suffices to care for the good of men and peoples." (Denzinger-Bannwart, n. 1703).

⁹ Cfr. Deut. VI, 13; Matth. IV, 10; Luke XXII, 42; John IV, 34; VI, 36.

¹⁰ Cfr. Saint Thomas, Summa Theol., 1a 2ae, qu. 90, art. 4, ad 1: "The promulgation of the law of nature consists in this very fact: that God implanted it in human minds to be known."

¹¹ "Lex rationis, quam ne ipsa quidem delet iniquitas." Epist., 157 (al. 80), n. 18 (Migne, P. L., XXXIII, 683); cfr. Confess., II, c. 4 (P. L., XXXII, 678).

¹² Ius naturale.

¹³ Cfr. Theodore Meyer, S.J., Die Grundsätze der Sittlichkeit und des Rechts, Freiburg 1868, pp. 147 sqq.; V. Cathrein, S.J., Moralphilosophie, Vol. I, 4th ed., pp. 485 sqq.

READINGS. —Theodore Meyer, S.J., Institutiones Iuris Naturalis, Vol. I, 2nd ed., Freiburg 1906.—G. von Hertling, Kleine Schriften zur Zeitgeschichte und Politik, Freiburg 1897, pp. 168 sqq. —C. Gutberlet, Ethik und Naturrecht, 3rd ed., pp. 123 sqq. —Jos. Rickaby, S.J., Moral Philosophy, pp. 133 sqq. —J. Haring, Der Rechts- und Gesetzesbegriff, Graz 1899, pp. 25 sqq. —V. Cathrein, S.J., Recht, Naturrecht und positives Recht, Freiburg 1901, pp. 101 sqq. —IDEM, in the Catholic Encyclopedia, Vol. V, pp. 562 sq. —R. I. Holaind, S.J., Natural Law and Legal Practice, New York 1899, pp. 37 sqq. —M. Cronin, The Science of Ethics, Vol. I, pp. 607 sqq. —A. Tanquerey, S.S., Synopsis Theologiae Moralis, Vol. II, pp. 123 sqq. —A. Sweens, Theologia Moralis Fundamentalis, 2nd ed., pp. 139 sqq.