I have been using this word in particular quite a lot lately. Some literary critique would therefore say that this word is of much importance to the author, to which I hold nothing against the statement. Only because it is a phenomenon that I have been seeing too much of, and I detest every single moment I bear witness to it.
There is no such thing as realizing a mistake, and justifying it.
Once a mistake is done, admittance follows, then apologies, then life goes on. Should things work out well after, then all is well. Should it not be the case, swallow it as bitter as it might be, then go on.
Justifying actions should only apply if the person believes that what prompted the action was the right thing to do. Read: No mistakes.
"I admit eating excessively is wrong. But I only do it because I'm stressed,"
That would be a day-to-day example (A bad one at that. Perhaps I could have come up with better examples though some might be offended. This, however, is NOT a justification). We could see more serious cases in the ways of killing and so on.
I do not think this is a difficult concept for one to grasp.