Even though common sense would tell you as much, I had never heard of detraction being a sin, until I began to learn about the Catholic Faith.

This was one thing that attracted me to Catholicism.  As I just told my mother a little while ago (I am doing home care for my father this morning), it is not so much that Catholicism differs from other Christian [sic] sects on the matter of "being a good person" or not, it is more that our morality is systematized, logic and reason are employed, and most of all, it is utterly dispassionate --- the same "rules" for everyone, there is none of this "this one believes this" and "that one believes that", it's black-and-white where it's black-and-white, and it's gray where it's gray.  I have a pet theory that this is why educated Catholics make so much better lawyers and judges (six, seven if you count Gorsuch, Supreme Court Justices are Catholic) --- our faith, and our way of thinking, is utterly objective, and we make fair decisions instead of tendentious ones.  (Sotomayor is a product of her times, upbringing, and culture.)

Degrees of gravity in both calumny and detraction:

DETRACTION
Just know that detraction can be either mortal or venial, depending on the severity of the behavior being reported, combined with the role/status of the person being detracted against, which may compound the detraction.

Thus, revealing a fault that you alone witnessed in so-and-so lay person and then passed along to another lay person (an equal of both of you) would normally be confessed as a venial sin.  However, if there was no cause or provocation in which to reveal that fault, one should examine one's conscience about the motive involved: Pride? (competition with that other) A private wish to stir up enmity with tale-bearing (another sin)? Envy? (an opportunity to diminish the stature of the other)

Heavier level: revealing a grave fault or grave sin in another lay person: Mortal sin.

Compounded gravity: revealing a hitherto unknown grave fault or grave sin in a consecrated person: Mortal sin.  By definition, if the revelation involves just protection of a vulnerable lay person, then the revelation is not detraction but an act of charity and justice.  However, merely revealing a grave problem or moral condition of a priest or other religious, for the purpose of spite, attention, or vanity would be mortally sinful.

CALUMNY
Given that calumny is by definition a lie, it seems not possible for it to be light matter because we are potentially destroying the reputation of another through falsehood.  It's a combination of two violations of justice and at least one violation of charity.

Compounded level: involving a consecrated person as either the object of false information or the receiver of false information about a member of that person's flock or similar subordinate relationship.

Three times in the last 8 years I have been the object of calumny at my parish, and in all three occasions that did include deliberate involvement of priests as the receivers of falsehoods.  I am not the only one to have suffered calumny at this parish; at least one other woman has been the object, more often than I, and over the same time period. The calumny was motivated by Envy in all of these cases.  The point is, the reason that the calumny is compounded in that case is that it corrupts the relationship of a lay person with his or her priest & often spiritual director and confessor. 

Edited to add that the previous sentence comes from a sermon about this by Fr. Ripperger.

Precisely for the reasons cited by Matto.  Detraction involves the revelation of a SECRET or HIDDEN fault.  This accusation of pride was based on your public posting and not based on some personal knowledge that is known to the accuser alone.  Call it a false accusation, perhaps even calumny, but it's not detraction.

I would disagree with how things went down.  If one were to make a judgment based on the original post (accusation of pride), then it might be a "public" revelation about THAT post.  And, even so, one would need to interpret that same post the same way to make the same judgment (in fact, we have seen that a number of posters in the original thread that did NOT judge it the same way).

I would say that when someone refers to LT's POSTING HISTORY here, then that is at least detraction despite the fact that all of his posting history is technically "public".  Why?  Because there are many members and lurkers here, many new posters in fact, that may not be aware of "LT's posting history".  Heck, I've been here a long time and I am not aware of all of his posts.  So, in that sense, it was a revelation of a supposed hidden fault.

If we're all honest with ourselves, we know that none of us are blameless and none of our posting histories are spotless.  In fact, I suspect that each and every one of us are.....prideful at least at times.  

The whole matter is....ironic.

What do you mean by: "since he was preset for the remarks".

It was supposed to be "present" but my phone thought otherwise. 

You were present in the discussion as the remarks were made, so in the case of that thread certain individuals were reviling you. Yet, as 2V pointed out, many of us do not know your posting history, and while that is "public" information if we take the time to look for it, in the context of the present case it would still constitute detraction because these supposed instances would have been hidden from our knowledge of you.

If one were to make a judgment based on the original post (accusation of pride), then it might be a "public" revelation about THAT post.  And, even so, one would need to interpret that same post the same way to make the same judgment (in fact, we have seen that a number of posters in the original thread that did NOT judge it the same way).

Why do you think we had some vocal posters in that thread that took the OP personally as a rebuke directed at them?

Case in point: I am a lurker and didn't think there was any reason to think he was being Pharasaical (I never saw and refuse to read what everyone is referring too) but now it's in my mind that there might be! I'm still not going to look up what people are referring to but it just shows that detraction is so easy.

I would say that when someone refers to LT's POSTING HISTORY here, then that is at least detraction despite the fact that all of his posting history is technically "public".  Why?  Because there are many members and lurkers here, many new posters in fact, that may not be aware of "LT's posting history".  Heck, I've been here a long time and I am not aware of all of his posts.  So, in that sense, it was a revelation of a supposed hidden fault.

If we're all honest with ourselves, we know that none of us are blameless and none of our posting histories are spotless.  In fact, I suspect that each and every one of us are.....prideful at least at times.  

The whole matter is....ironic.

No, the problem came when Matto disagreed with Last Trad's use of the term "detraction" ... which Last Trad took as a personal attack from Matto.