Knowledge and mortal sin

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.)

In some senses I think you are sort of right, and most importantly personal mental limitation. Someone who is low on the intelligence spectrum may both “know” and not know something do to understanding capabilities.

On the bold part, here is the important part. At a certain point theologically speaking it isn’t if YOU “know” it to be wrong unto itself, it is if you KNOW GOD says it is wrong.

Note Abraham and Isaac… GOD over conscience at that point.

Earthly wise I would say these people are doing just what you said and REJECTING the church teaching and God’s truth etc…

Heavenly wise, if it is due to a true inability to grasp the truth and mental limitation…a lot of people who seem defiantly sinful to us may be going to heaven like a small child. I mean even a 2 yr old knows in most cases they cant “steal” in a sense…but are not mentally capable of living up to it.

For example I grew up similar, culture catholics. You go to CCD, (not mass though, that is just weird) then after confirmation you go back to church for weddings and funerals. So along the way even with CCD do to social conditioning it is feasible that I would be considered essentially ignorant for a chunk of time before gaining my own understanding. And if people can be conditioned mentally in as many ways as we know…it is possible that there is even a bit of leeway for us when we start to realize we are wrong, but can not quite break free of the conditioning.

My greatest wonder if mental states last in eternity? the hierarchy often described in Heaven. If these people are not blessed with some kind of mental boost, I presume they would be subject to the lower end of the hierarchy? Given I can not break free of some doubt and therefore can still sin, me too :frowning: ? ugh… eh it’ll still be cool I think :slight_smile: Sadly I am pretty sure I am going to purgatory for a while :confused:

My own experience of dissenting Catholics, is they all genuinely believe that what they want is what God wants, and those Church authorities (such as the Pope and the Bishops) who disagree with them have got God’s will wrong. You can see them as rejecting God’s will; that may well be true objectively, but that’s not what’s happening from the subjective viewpoint of their own psychology. The person who says to themselves “I know God is opposed to X, but I don’t care what God wants, so I’ll have X anyway” – maybe somewhere such a person exists, but that isn’t a very common psychology. Much more common psychology is “I want X, so God must want X too, the people who say God doesn’t must have got it wrong”.

My own late grandmother, bless her soul, while she was in many ways quite devout, she was also a strong advocate of woman’s ordination. (I never heard her call herself a “feminist”, but a lot of what she used to say had a feminist ring to it.) She honestly believed that the Popes had got this wrong, well because they are men, and as a woman she had a better understanding of what God wanted on these issues than any man possibly could. She had a lot of friends who were nuns, and many of them shared her beliefs on this issue (although they were careful not to be too loud about it to avoid negative attention from the Church authorities.) I am quite sure she honestly believed she was doing God’s will. She was never involved in public activism on the issue, because she was busy caring for her children and grandchildren, and making noise about things publically wasn’t her style; but still, it’s not like the noisy public way is the only way to make a difference on an issue, sometimes the quiet approach can make a bigger impact in the long-run than the loud and noisy one. i.e. How many of her children and grandchildren have inherited this belief from her? I think the vast majority of them have. Even the atheists in my family believe in women’s ordination (as contradictory as that position might seem.)

I used to agree with her, I don’t any more. I’ll be honest, the big thing that convinced me wasn’t any theological argument, I just don’t think that women’s ordination will do the Church any good in the long run, more for pragmatic/sociological reasons. If you look at what’s happening to the Anglican Communion and to Mainline/Liberal Protestantism, the future doesn’t look very bright for them, but I suspect women’s ordination would push the Catholic Church down the same unhealthy path. Also, maybe this is unfair, but I feel like women are more frequently the perpetrators of liturgical cringeworthiness than men, which makes me suspect that women’s ordination would bode poorly for the future of the Church’s liturgy. But most of my own extended family would disagree with me on this, most of them (and I come from large Catholic families on both sides) still support women’s ordination.

There is a lot of objections to the Justified True Belief view of knowledge, so be careful when using that as a starting point.

Beyond that, let us look at the issue from a different point of view:
Consider a child and her father. The child knows when she has done wrong, and knows to avoid doing wrong. She knows this independently of having full knowledge (in your JTB view). Yet, the father will still punish for her transgressions.

Obviously, the gap between humans and God is much, much larger than that. However, this illustration shows that we can know something is wrong-very wrong in fact- without fully understanding the problem.

When it comes to mortal sin, I do not think we need an omniscient understanding, but a working understanding. This working understanding varies from person to person, and why a mortal sin for one person may not be a mortal sin for another person.

I would set aside those ideas.

Rather go to the Church - ie Catechism, moral theology etc.

Study what the Church and Theology means by term “full knowledge” (or full advertence).

I would set aside those ideas.

Rather go to the Church - ie Catechism, moral theology etc.

Study what the Church and Theology means by term “full knowledge” (or full advertence).


In my experience, Catholic schools, in the last 40 years or so, have emphasized this:

*1777 Moral conscience,48 present at the heart of the person, enjoins him at the appropriate moment to do good and to avoid evil. It also judges particular choices, approving those that are good and denouncing those that are evil.49 It bears witness to the authority of truth in reference to the supreme Good to which the human person is drawn, and it welcomes the commandments. When he listens to his conscience, the prudent man can hear God speaking.

1779 It is important for every person to be sufficiently present to himself in order to hear and follow the voice of his conscience. This requirement of interiority is all the more necessary as life often distracts us from any reflection, self-examination or introspection:
1792 Ignorance of Christ and his Gospel, bad example given by others, enslavement to one’s passions, assertion of a mistaken notion of autonomy of conscience, rejection of the Church’s authority and her teaching, lack of conversion and of charity: these can be at the source of errors of judgment in moral conduct.

1793 If - on the contrary - the ignorance is invincible, or the moral subject is not responsible for his erroneous judgment, the evil committed by the person cannot be imputed to him. It remains no less an evil, a privation, a disorder. One must therefore work to correct the errors of moral conscience.

But not this:

*1791 This ignorance can often be imputed to personal responsibility. This is the case when a man "takes little trouble to find out what is true and good, or when conscience is by degrees almost blinded through the habit of committing sin."59 In such cases, the person is culpable for the evil he commits.


I agree mostly but I still think maybe 25 - 50% know it is wrong, they just dont wanna.

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