Off the top of my head, it’d be a perversion of the natural use of our communicative faculty (to relay truths relevant to myself or my environment to others) to tell a lie, hence lying is contrary to the natural law.
The natural use of the digestive faculty is to provide nourishment to the body so that it can survive, hence it would be a sin to eat excessively (i.e., to eat so much food that one’s health is impaired) and otherwise disorderedly (i.e., inducing vomiting after tasting the food).
The natural use of the respiratory faculty is to provide oxygen to the body, so it’d be a sin to deliberately hold one’s breath until one blacks out for the sake of getting high.
I have often heard of natural law outside of the context of sexuality. Usually referring to sins that the “heart” knows is wrong.
Like murder. One does not need a Church to tell them murder is wrong, because" it is written on the heart of man" These sorts of “natural law” subjects come up when discussing salvation or sin issues “outside” of the faith.
No, the screwdriver has a creator. A company who wants you to use it for anything you need it for within the confines of morality. For instance a screwdriver can pry open a paint can but you could not use it to pry open a victims chest cavity. Natural law in your example would be something like this. A screwdriver is a tool for screwing and unscrewing, I am going to use it as a telescope.
Unnatural acts also include suicide, murder as mentioned, turning on one’s allies, starving oneself, overreating, unnecessary/excessive spending of money/resources, etc
Things which, if we were left in our natural state, wouldn’t make sense to the preservation of ourselves or society. However, using a screwdriver to open a paint can isn’t “unnatural” in this sense. In fact, it’s handy. Resourceful, even! Committing suicide though, not so much.
“The natural law is the law of human being alone—not other animals, not birds, not rocks, not trees, not planets. The natural law arises from our particular nature. It is natural insofar as it is rooted in our nature, and moral insofar as our nature defines what is good and evil for us.
“Well, just what are we? We are rational, moral animals—the only rational, moral animals. We are the one animal that must think even to survive, and the one animal whose actions are not governed by instincts but are judged by standards of good and evil. We don’t consider it cruel not to teach your dog to read, but we think that keeping children from getting an education deprives them of something they should have. We don’t jail rambunctious roosters for forcing themselves on beleaguered hens, but we send men to the slammer for rape.
“Our status as the only rational, moral animal is the source of our natural belief that human beings are distinct from other animals. That is the origin of all laws against murder, for the notion of “murder” assumes that killing a human being is fundamentally distinct from killing a chicken, and that the murderer actually had the moral freedom not to kill (otherwise, jailing the man would make as much sense as jailing the knife). Let go of this fundamental assumption, and soon killing anything will be considered murder (as some animal rights activists maintain) and a murderer’s DNA will be the only culprit (as genetic determinists maintain).
“This status as rational animal is exactly what is meant by the assumption that human beings are made in the image of God. The Ten Commandments are, in moral substance, not unique to the ancient Jews. As C. S. Lewis noted in his Abolition of Man, the moral commands to honour parents, not murder, not lie, not steal, and so on, are found everywhere. They are found everywhere because they arise from human nature. To ignore them, or manipulate them, can only result in the destruction of human nature, the Abolition of Man.”
Dr. Benjamin Wiker
I think there may have been a misunderstanding of the meaning of the word “natural” in the context of “natural law” here. Abu’s post has the correct sense:
The Catechism has a lot to say about natural law. I find it interesting that the Catechism refers to it as the “divine and natural law.” That phrase does not refer to two different kinds of law, divine on one hand and natural on the other. No, it means that the natural law is divine as well. It is by “the Creator’s very good work” that we are formed in the image of God, and that the natural moral law is imprinted in our nature.
For your convenience, I quote the entire section on natural law here: I. The Natural Moral Law
1954 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 expresses the original moral sense which enables man to discern by reason the good and the evil, the truth and the lie:
[INDENT]The natural law is written and engraved in the soul of each and every man, because it is human reason ordaining him to do good and forbidding him to sin… But this command of human reason would not have the force of law if it were not the voice and interpreter of a higher reason to which our spirit and our freedom must be submitted. 1955 The “divine and natural” law6 shows man the way to follow so as to practice the good and attain his end. The natural law states the first and essential precepts which govern the moral life. It hinges upon the desire for God and submission to him, who is the source and judge of all that is good, as well as upon the sense that the other is one’s equal. Its principal precepts are expressed in the Decalogue. This law is called “natural,” not in reference to the nature of irrational beings, but because reason which decrees it properly belongs to human nature:
Where then are these rules written, if not in the book of that light we call the truth? In it is written every just law; from it the law passes into the heart of the man who does justice, not that it migrates into it, but that it places its imprint on it, like a seal on a ring that passes onto wax, without leaving the ring.
The natural law is nothing other than the light of understanding placed in us by God; through it we know what we must do and what we must avoid. God has given this light or law at the creation.
1956 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. It expresses the dignity of the person and determines the basis for his fundamental rights and duties:
For there is a true law: right reason. It is in conformity with nature, is diffused among all men, and is immutable and eternal; its orders summon to duty; its prohibitions turn away from offense… To replace it with a contrary law is a sacrilege; failure to apply even one of its provisions is forbidden; no one can abrogate it entirely. 1957 Application of the natural law varies greatly; it can demand reflection that takes account of various conditions of life according to places, times, and circumstances. Nevertheless, in the diversity of cultures, the natural law remains as a rule that binds men among themselves and imposes on them, beyond the inevitable differences, common principles.
1958 The natural law is immutable and permanent throughout the variations of history; it subsists under the flux of ideas and customs and supports their progress. The rules that express it remain substantially valid. Even when it is rejected in its very principles, it cannot be destroyed or removed from the heart of man. It always rises again in the life of individuals and societies:
Theft is surely punished by your law, O Lord, and by the law that is written in the human heart, the law that iniquity itself does not efface. 1959 The natural law, the Creator’s very good work, provides the solid foundation on which man can build the structure of moral rules to guide his choices. It also provides the indispensable moral foundation for building the human community. Finally, it provides the necessary basis for the civil law with which it is connected, whether by a reflection that draws conclusions from its principles, or by additions of a positive and juridical nature.
1960 The precepts of natural law are not perceived by everyone clearly and immediately. In the present situation sinful man needs grace and revelation so moral and religious truths may be known “by everyone with facility, with firm certainty and with no admixture of error.” The natural law provides revealed law and grace with a foundation prepared by God and in accordance with the work of the Spirit.[/INDENT]
The counterpart to natural law is revealed law (CCC 1961-1974).
IVF offends natural law in a couple of ways. Like abortion it does not respect the inviolability of human beings and their intrinsic right to life with regard to embryos that are destroyed or discarded.
Most of all, it regards persons as objects in service to other people by nature. The type of manipulative power might equate to slavery or the unnecessary use of capital punishment which rely on some regarding others as intrinsically subservient or expendable.