Intrinsically Wrong vs Gravely Wrong
I think that it is Catholic moral teaching that all intrinsically wrong sexual acts are gravely wrong. All sexual sins are grievous sins. According to my Church: If an intrinsically wrong sexual act is done after sufficient reflection and full consent, it is a mortal sin. It must be absolved through the sacrament of reconciliation before the sinner is worthy to receive the Eucharist. If an intrinsically wrong act is not gravely wrong, it is only a venial sin. The fact that the gravity of all sexual sins is taught indicates that there is a distinction to be made between intrinsically wrong and gravely wrong.
An act is intrinsically wrong, if there are no circumstances, intentions or consequences under which it is morally permissible. It is always and everywhere simply wrong. For instance, shoplifting a candy bar from a UDF convenience store simply because you want it, is simply wrong: No excuses. The shoplifting is in the same class of criminal acts as robbing a UDF at gunpoint simply because you want the cash. Imagine how you think of the act of a teenage son caught doing the shoplifting.Once we think about how we conduct our daily lives, we can recall all sorts of little acts of rudeness, carelessness and dishonesty that were simply wrong.
I hope these few remarks suffice to show that for those who concede that there are intrinsically wrong acts, intrinsically wrong acts are not necessarily gravely wrong acts. Indeed, even those who do not concede that there are intrinsically wrong acts should concede the conceptual distinction.
Moral theory can tell us how to distinguish between acts which are intrinsically wrong and those which are only accidentally wrong. Determination of moral gravity is, I think, determined by the consequences of the act. But what kind of consequences and how to weigh them is too complex to consider here.
We should, though, avoid the fallacious inference from “it is not gravely wrong” to “It is not wrong.”
In a later post, I argue that careful moral thinking has no place for talk of moral gravity. See Inconsistency of moral gravity.