God leads all things by His eternal law, often portrayed as Lady Wisdom in the Old Testament. See Ps. 19:7-10, 119; Prov. 3:13-25, 8:1-9:18; Sir. 1:1-18; Wis. 7:14-10:21. As St. Thomas Aquinas points out, the eternal law is the primordial principal upon which all other governance is based. See Summa Theologica II-I q. 93 art. 1.
The moral law is God’s guidance that we may use our freedom well to participate in that eternal wisdom. “The moral law is the work of divine Wisdom. Its biblical meaning can be defined as fatherly instruction, God’s pedagogy. It prescribes for man the ways, the rules of conduct that lead to the promised beatitude; it proscribes the ways of evil which turn him away from God and His love. It is at once firm in its precepts, and in its promises, worthy of love Man participates in the wisdom and goodness of the Creator who gives Him
mastery over his acts and the ability to govern himself with a view to the true and the good. .
. . The natural law, present in the heart of each man and established by reason, is universal in its precepts and its authority extends to all men.” Catechism 1949, 1954, 1956. We can thus see the commandments of God as increasing our ability to be truly free, to participate in God’s creative goodness. See, e.g., John 8:31-32; James 1:25.
Some principles (e.g., The Ten Commandments, the Beatitudes) are always and everywhere true by their nature. Other laws (e.g., the ritual laws of the ancient Jews or the liturgical laws of the Church) are still based upon the moral law, but can be changed according to circumstances. Civil laws likewise should be based upon the moral law, but can and should be changed according to circumstances if a different way of doing things (e.g., taxation, zoning, judicial proceedings) would now work better. Governments (whether ecclesial, political, economic or other) are thus good, so long, and only as long, as they uphold the moral law of God. As Jesus says, “Render unto Caesar what is Caesar’s, but render unto God what is God’s.” Matt 22:21; Mark 12:17; Luke 20:25. St. Paul likewise says that human authority is meant to be from God. See Rom. 13:1-7.
There are some fundamental principles of human nature that are at the very heart of virtuous living and thus are the foundation of all other moral laws.
The love of God and neighbor are at the heart of all good laws. When asked what the greatest commandment is, Jesus replied, “‘You shall love the Lord your God with all your heart, with all your soul, and with all your mind.’ This is the great and first commandments. And a second is like it, ‘You shall love your neighbor as yourself.’ On these two commandments depend all the law and the prophets.” Matt. 22:37-40. Likewise, St. John wrote, “He who does not love the brother whom he does see cannot love the God whom he does not see.” 1 John 4:20-21. Building on the love of neighbor, there is the principle that another person should never be used as an object, but rather looked at as an immortal and sacred person, beloved of God. See, e.g., Catechism 1931.
Jesus gave enunciated basic principles in other sermons, most prominently in the Sermon on the Mount when He said such things as, “Seek first His kingdom and His righteousness, and all these things shall be yours as well,” and “Whatever you wish that men would do to you, d so to them; for this is the law and the prophets.”
Another fundamental principle is that one should never commit an action that is inherently wrong so even for the purpose of making a good come from it. Matt. 5:19; Catechism 1753, 1756, 1761, 1789.
The conscience is the testimony to this moral law that is in each person. One’s conscience is God’s ambassador in the soul. As such the conscience is compelling, but it can be an imperfect ambassador, for it can be in error.
Each person has a conscience, a desire for truth and goodness. As St. Paul says, “When the Gentiles who do not have the law by nature observe the prescriptions of the law, they are a law unto themselves, even though they do not have the law. They show that the demands of the law are written in their heart.” Rom. 2:14. The Catechism describes this principle in more detail, saying, “Moral conscience, present at the heart of the person, enjoins him at the appropriate moment to do good and to avoid evil. It also judges particular choices, approving those that are good and denouncing those that are evil. It bears witness to the authority of truth in reference to the supreme God to which the human person is drawn, and it welcomes the commandments. When he listens to his conscience, the prudent man can hear God speaking.” Catechism 1777.
As a result, one should always abide by one’s conscience, for it is our way of hearing God’s commands. And this obligation is the firmest foundation for individual dignity and political rights. For example, as the Vatican II Council’s document on religious liberty says, the obligation to pursue the truth and adhere to it once known is the basis for religious and intellectual freedom. See Dignitatis Humanae 2. This divine obligation is in fact the firmest grounding for the idea of human rights and dignity.
- Unfortunately, people often speak about rights while ignoring this calling of conscience, which is its fundamental base. As Pope Emeritus Benedict XVI wrote in Caritas in Veritate (2009) section 43, people today are often “concerned only with their rights, and they often have great difficulty in taking responsibility for their own and other people's integral development. Hence it is important to call for a renewed reflection on how rights presuppose duties, if they are not to become mere license.
Nowadays we are witnessing a grave inconsistency. On the one hand, appeals are made to alleged rights, arbitrary and non-essential in nature, accompanied by the demand that they be recognized and promoted by public structures, while, on the other hand, elementary and basic rights remain unacknowledged and are violated in much of the world.”
However, conscience, as glorious as it is, can be in error. Like any other human skill, it must be developed, or it will fail altogether. “Conscience must be informed and moral judgment enlightened. . . . The education of the conscience is a lifelong task. . . In the formation of conscience the Word of God is the light for our path; we must assimilate it in faith and prayer and put it into practice. We must also examine our conscience before the Lord’s Cross. We are assisted by the gifts of the Holy Spirit, aided by the witness or advice of others and guided by the authoritative teaching of the Church.” Catechism 1783-1785.
Because the human conscience is fallible and limited, God reveals things to us about the moral law both by Scripture and the Church.
We certainly have a calling to develop our reason naturally by careful thinking,
knowledge and consultations with other people. It is natural wisdom to understand that the development of a conscience is both essential and difficult.
Precisely because it is not easy to develop our consciences, and because we can easily be in error, both individually and as a society, God also gives us revelation about what is true and false in human action as well as in external fact. See St. Thomas Aquinas, Summa Theologica II-I q. 91 art. 4.
God revealed the beginnings of the law to the ancient Jews, in preparation for their completion in the preaching of Christ. “God, our Creator and Redeemer, chose Israel for Himself to be His people and revealed His Law to them, thus preparing for the coming of Christ The Old Law is the first stage of revealed Law. Its moral
prescriptions are summed up in the Ten Commandments. The precepts of the Decalogue [the Ten Commandments] lay the foundation for the vocation of man fashioned in the image of God; they prohibit what is contrary to the love of God and neighbor and prescribe what is essential to it.” Catechism 1961 - 1962.
Jesus Christ then built upon the ancient covenant by revealing a more advanced law (but one still consistent with the ancient law) that calls us to live out the highest aspirations of the human life. Thus, for example, we receive in the Gospels the Beatitudes, the gifts of the Holy Spirit and the striving to learn and live out the example or Jesus Christ and the saints through the love of God and neighbor. “The New Law, or the Law of the Gospel, is the perfection here on earth of the divine law, natural and revealed. The New Law is the grace of the Holy Spirit given to the
faithful through faith in Christ. It works through charity; it uses the Sermon on the Mount to teach us what must be done and makes use of the sacraments to give us the grace to do it.” Catechism 1965, 1966
Because the Scriptures do not answer all questions clearly (e.g., just war theory, when children should be baptized, and who should do so), and because new questions arise (e.g., over the role of government in a mercantile economy, genetic engineering and other bioethical matters), God also gave the Church the ability to hand down teachings on moral issues. Thus, “the Church, the pillar and bulwark of the truth, has received this solemn command of Christ from the apostles to announce the saving truth. To the Church belongs the right always and everywhere to announce moral principles, including those pertaining to the social order, and to make judgments on any human affairs to the extent that they are required by the fundamental rights of the human person or the salvation of souls.” Catechism 2032.