One of the necessary conditions for a sin to be mortal, is that the sinner must have full knowledge, both of its wrongfulness and of the gravity of its wrongfulness.
I did a semester of epistemology at university, and we were taught this definition of knowledge: “knowledge is justified true belief”. According to this definition, in order to know something, (1) it must be true, (2) I must believe that it is true, (3) my belief must be rationally justified.
Now, combining this definition of knowledge with the definition of mortal sin: for a sin to be mortal, I must know both its wrongfulness and the gravity of its wrongfulness; in order for me to know something, I must believe it; hence, in order for a sin to be mortal, I must believe both that it is wrong and that it is gravely wrong.
Is that conclusion valid? That in order for a sin to be mortal, the sinner must believe that it is seriously wrong?
As a matter of psychology, I think most people who commit serious sins either don’t believe that their actions are wrong, or else don’t believe that the wrongfulness is serious. Consider for example sexual sins; I think, in today’s world, the vast majority of people who commit sexual sins either believe they are doing nothing wrong, or else believe that the wrongfulness of their acts is only slight or moderate rather than grave.
But if that is true, would it not follow that the knowledge condition for mortal sin is rarely met? Which would imply, that while objectively grave sin is common, mortal sin is rare. Is that a fair conclusion?
Or, if it is a mistaken conclusion, at which point above has my reasoning gone astray?
Of course, I haven’t touched on the distinction between invincible and vincible ignorance–I understand that a sin can be mortal, even if the sinner is ignorant of its wrongfulness (or the gravity thereof), if they are sufficiently culpable for their ignorance. But even there, it seems to me that most people in contemporary Western culture exist in a state of invincible moral ignorance, especially when it comes to questions of sexual morality. Most people inhabit a secular culture which increasingly declares that unlimited sexual indulgence is an inalienable human right, and anyone who dares to disagree is an evil bigot. If that’s what you’ve been raised to believe, and you’ve never heard any serious advocacy of any alternative, how can your moral ignorance be culpable?
Even within the Church, the quality of catechesis on sexual morality is in general quite poor, in many places close to non-existent. The majority of Catholics who dissent from the Church’s teachings on sexual morality have never once heard those teachings advocated and explained in a thoughtful way. Well, in 11 years of Catholic school, I never did, and I think I’m far from the only person with that experience. My impression is, that in my Catholic high school, the majority of staff and parents (quietly) rejected multiple points of the Church’s moral teaching, and the minority who consistently and wholeheartedly accepted the Church’s teachings were too frightened of offending the dissenting majority to dare broach the topic. How could my classmates and I be expected to know that certain acts are wrong if no one ever bothered to tell us? And I was in high school in the mid-to-late 1990s; if that was then, I wonder what it’s like now?
One of my high school classmates now works as a teacher at the same school. In the 1990s, the attitude of the school administration to homosexuality was to try to pretend it didn’t exist, neither approving of it nor saying anything critical of it; the attitude of the student body was mixed but overall somewhat negative. My classmate tells me, that while the attitude of the school administration is largely unchanged, the culture of the student body has changed a lot, and has become very accepting of homosexuality. I’m not going to name the school, because I don’t want it to be about that particular school – I think the majority of Catholic high schools are likely much of the same. (My city has a couple of Opus Dei high schools, but I don’t know anyone who went to them; maybe the student experience there is quite different, but even so they’d be very much the minority of Catholic high schools.)