Two of the heresies which are growing in modern society are the denial of natural law and the denial of free will. Readers have the list of free will posts here below......
Let me start with the first problematic belief, which takes the shape of people denying responsibility for actions because "they do not know" something is wrong.
The Catholic Encyclopedia is a good starting place for the understanding of natural law. The entire idea hinges on the fact that human being were created in the image and likeness of God.
Such philosophies are relativism, subjectivism and determinism deny the fact that we are all created to be with God in heaven, that we have this goal from the very fact that we are human beings, and that our intelligence and free will guide our actions and thoughts.
In other words, anything which is against human nature, as created by God, is against natural law. Human nature is the discriminating norm for natural law.
According to St. Thomas, the natural law is "nothing else than the rational creature's participation in the eternal law" (I-II.94). The eternal law is God's wisdom, inasmuch as it is the directive norm of all movement and action. When God willed to give existence to creatures, He willed to ordain and direct them to an end. In the case of inanimate things, this Divine direction is provided for in the nature which God has given to each; in them determinism reigns.
Like all the rest of creation, man is destined by God to an end, and receives from Him a direction towards this end. This ordination is of a character in harmony with his free intelligent nature. In virtue of his intelligence and free will, man is master of his conduct. Unlike the things of the mere material world he can vary his action, act, or abstain from action, as he pleases. Yet he is not a lawless being in an ordered universe. In the very constitution of his nature, he too has a law laid down for him, reflecting that ordination and direction of all things, which is the eternal law. The rule, then, which God has prescribed for our conduct, is found in our nature itself. Those actions which conform with its tendencies, lead to our destined end, and are thereby constituted right and morally good; those at variance with our nature are wrong and immoral.
To be human is to have knowledge of natural law. God ordered the universe and, specifically, human nature, to reflect Himself. The Divine nature informs human nature, and the Divine authority gives all all an innate obligation to follow natural law.
The discriminating norm is, as we have just seen, human nature itself, objectively considered. It is, so to speak, the book in which is written the text of the law, and the classification ofhuman actions into good and bad. Strictly speaking, our nature is the proximate discriminating norm or standard. The remote and ultimate norm, of which it is the partial reflection and application, is the Divine nature itself, the ultimate groundwork of the created order. The binding or obligatory norm is the Divine authority, imposing upon the rational creature the obligation of living in conformity with his nature, and thus with the universal order established by the Creator. Contrary to the Kantian theory that we must not acknowledge any other lawgiver than conscience, the truth is that reason as conscience is only immediate moral authority which we are called upon to obey, and conscience itself owes its authority to the fact that it is the mouthpiece of the Divine will and imperium. The manifesting norm (norma denuntians), which determines the moral quality of actions tried by the discriminating norm, is reason. Through this faculty we perceive what is the moral constitution of our nature, what kind of action it calls for, and whether a particular action possesses this requisite character.
The ability to reason is the faculty given to us by God, separating us from all other creatures, gives us the clarity as to what is moral, what action follows this knowledge of morality in a specific situation, and whether an action is moral.
This ability is in us by the very fact that we are human, and not because we are in sanctifying grace although sanctifying grace can inform natural law and lead to an understanding of other laws.
And, here comes an area of confusion for moderns: there are primary and secondary binding precepts.
To the first class belong those which must, under all circumstances, be observed if the essential moral order is to be maintained. The secondary precepts are those whose observance contributes to the public and private good and is required for the perfection of moral development, but is not so absolutely necessary to the rationality of conduct that it may not be lawfully omitted under some special conditions.
In addition, natural law is universal, to all people of all times.
Natural law is immutable; as long as humans exist, natural law exists.
And, here is the answer to those modern lawyers of all kinds who deny natural law. There is a new class both of civil and canon lawyers who have erroneously moved away from natural law philosophy.
The question arises: How far can man be ignorant of the natural law, which, as St. Paul says, is written in the human heart (Romans 2:14)? The general teaching of theologians is that the supreme and primary principles are necessarily known to every one having the actual use of reason. These principles are really reducible to the primary principle which is expressed by St. Thomas in the form: "Do good and avoid evil". Wherever we find man we find him with a moral code, which is founded on the first principle that good is to be done and evil avoided. When we pass from the universal to more particular conclusions, the case is different. Some follow immediately from the primary, and are so self-evident that they are reached without any complex course of reasoning. Such are, for example: "Do not commit adultery"; "Honour your parents". No person whose reason and moral nature is ever so little developed can remain in ignorance of such precepts except through his own fault. Another class of conclusions comprises those which are reached only by a more or less complex course of reasoning. These may remain unknown to, or be misinterpreted even by persons whose intellectual development is considerable.
Without Revelation, natural law is much harder to discern. Therefore, humans have a duty to pursue Revelation and supernatural law. See Vatican Council, Sess. III, cap. ii CE
to be continued.....................