The assertion in the title — If lying isn’t always wrong, then nothing is always wrong — is predicated on two truths, two teachings of the Church.
1. Lying is intrinsically evil.
Lying is in the category of intrinsically disordered acts, i.e. acts that are immoral by their very nature. One and only one thing makes any act intrinsically evil: an evil moral object. All those acts and only those acts with an evil moral object are intrinsically evil.
“By its very nature, lying is to be condemned.” [CCC 2485]
“A good intention (for example, that of helping one’s neighbor) does not make behavior that is intrinsically disordered, such as lying and calumny, good or just. The end does not justify the means.” [CCC 1753]
Every act that is immoral “by its very nature” is intrinsically evil. Every intrinsically disordered act is intrinsically evil. These terms are used interchangeably in the teaching of the Church. Thus, the CCC clearly teaches that lying is intrinsically evil.
2. Intrinsically evil acts are always immoral.
The Church teaches that intrinsically evil acts (acts with evil in their object) are always immoral.
“Reason attests that there are objects of the human act which are by their nature ‘incapable of being ordered’ to God, because they radically contradict the good of the person made in his image. These are the acts which, in the Church’s moral tradition, have been termed ‘intrinsically evil’ (intrinsece malum): they are such always and per se, in other words, on account of their very object, and quite apart from the ulterior intentions of the one acting and the circumstances.” [Veritatis Splendor 80]
“If acts are intrinsically evil, a good intention or particular circumstances can diminish their evil, but they cannot remove it. They remain ‘irremediably’ evil acts; per se and in themselves they are not capable of being ordered to God and to the good of the person.” [Veritatis Splendor 81]
“No circumstance, no purpose, no law whatsoever can ever make licit an act which is intrinsically illicit, since it is contrary to the Law of God which is written in every human heart, knowable by reason itself, and proclaimed by the Church.” [Evangelium Vitae 62]
There are no exceptions. Every intrinsically evil act, whether a venial sin or a mortal sin, whether a venial lie or the grave sin of murder, is always immoral.
“A morally good act requires the goodness of the object, of the end, and of the circumstances together. An evil end corrupts the action, even if the object is good in itself (such as praying and fasting ‘in order to be seen by men’). The object of the choice can by itself vitiate an act in its entirety. There are some concrete acts – such as fornication – that it is always wrong to choose, because choosing them entails a disorder of the will, that is, a moral evil.” [CCC 1755]
“It is therefore an error to judge the morality of human acts by considering only the intention that inspires them or the circumstances (environment, social pressure, duress or emergency, etc.) which supply their context. There are acts which, in and of themselves, independently of circumstances and intentions, are always gravely illicit by reason of their object; such as blasphemy and perjury, murder and adultery. One may not do evil so that good may result from it.” [CCC 1756]
Lying can be a venial sin or a mortal sin, but “every lie is a sin” [Summa Theologica III Q 110 A 3; On Lying 1]. The reason that lying is always wrong is that lying is intrinsically evil. Every intrinsically evil act is always immoral. Gravely disordered intrinsically evil acts are always gravely immoral.
Many acts, in addition to lying, are intrinsically evil and therefore always immoral: theft, murder, adultery, contraception, abortion, euthanasia, murder, rape, various other sexual sins, and the severe sins of slavery and genocide. All these acts are intrinsically evil and therefore always wrong.
The problem with finding some creative way to justify lying, is that every other intrinsically evil act would also be justifiable on the same basis. For every intrinsically evil act is immoral because of its moral object, independent of intention or circumstances or other acts. And we cannot redefine lying, or any other intrinsically evil act, so that the act would be justifiable despite an evil moral object, or so that what is claimed to be the object would actually be an intention or a circumstance or something else. All such approaches reject the definitive teaching of the Magisterium on intrinsic evil.
“But the negative moral precepts, those prohibiting certain concrete actions or kinds of behaviour as intrinsically evil, do not allow for any legitimate exception. They do not leave room, in any morally acceptable way, for the ‘creativity’ of any contrary determination whatsoever. Once the moral species of an action prohibited by a universal rule is concretely recognized, the only morally good act is that of obeying the moral law and of refraining from the action which it forbids.” [Veritatis Splendor 67]
If lying is not always wrong, then no intrinsically evil act is always wrong. For all intrinsically evil acts are immoral on the same basis, due to an evil moral object, regardless of every other consideration. There is no room for any creative way to justify intrinsically evil acts in some cases, nor to justify one intrinsically evil act, and not every other intrinsically evil act. The morality of intrinsically evil acts works the same way, whether the act is a venial lie or the exceedingly grave and horrific sins of slavery or genocide.
If lying is not always wrong, then nothing is always wrong. However, as the holy Catholic Church teaches and as I also believe and teach:
Lying is always wrong.
Theft is always wrong.
Murder is always wrong.
Abortion is always wrong.
Euthanasia is always wrong.
Adultery is always wrong.
Same-sex marriage is always wrong.
Premarital sex is always wrong.
Rape is always wrong.
Slavery is always wrong.
Genocide is always wrong.
All intrinsically evil acts are always immoral, because the chosen act is inherently ordered toward an evil end, called its moral object. When the moral object of an act is evil, the act is intrinsically evil and always wrong to knowingly choose. There are no exceptions for lying, just as there are no exceptions for theft, murder, rape, slavery, or genocide. Whosoever justifies lying, regardless of the explanation, necessarily implies that all other intrinsically evil acts can also be justified in the same way.
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