Fallacy: "you know what you did!"

So... in one of my classes, we were challenged to come up with a story, then we were told to write a sort of monologue for the main character. then we were told to justify the Antagonist's views.

I didn't have a story in mind(the one I had come up with didn't really work for the last exercise), so I started coming up with general motivations for someone to do what they do.

-The end result is all that matters. "the end justifies the means".
This is where an antagonist could truly want the BEST results and does "whatever it takes" to attain that end., but then again, what's "best" is pretty subjective isn't it?
-Love. "true love conquers all".
This is a more identifiable view than doing something out of hate. hate makes you bad, love makes you good (or at least misunderstood).
-Religion. ...not gonna go there, but it has a LOT of potential
-Insanity
This is actually something that strikes me as very, very interesting in a story. Anyone who has seen Adaptation (with Nicholas Cage, Chris Cooper, and that one woman)
and has anything to do with writing knows that this is the cheapest way to "twist" a story... Fight Club, Secret Window, maybe even Psycho. Where we are told at the last second that someone was crazy and that explains everything. it's usually unsettling, but generally I think it makes for a weakened message.
However, if this insanity isn't a twist, if it is acknowledged very early on... then I think that makes for a very human, very pitiable perp. Of mice and Men-kinda.

Anyway. that's that.

I also learned something recently about communication, hence the title of this post.
'You know what you did' is probably the most false statement anyone can presume to make. I think that the key part of that phrase is "did". No one DOES just one thing. any behavior or action can actually have myriad effects. So when someone asks innocently "what did I do?" it's probably best to relate to them exactly what you perceived that they did. Because that might be brand new information to this alleged "perpetrator".

Letting this assumption, that each other "knows what they did", go unaddressed is incredibly detrimental. When someone does something, and you assume you know why, then you are inclined to respond in defense or response to their perceived motive. If you are hurt, you may want to get even, or you may want to be pitiful and hope they "come around". This quite often results in a cycle. "You hurt me, I hurt you, you get even, I get even, you one-up, I one-up" back and forth, until someone throws in the towel, or someone goes too far. The proper way to address being hurt (i'm learning) is to not assume ill will-- there is no "perp". Instead, you must assume that the offender is unaware of your pain, and inform them of it. Most likely they are unaware, or if they ARE aware, they will probably tell you the reason they did what they did. Their reason may actually be that they are getting back at you for hurting them, and you had NO idea that you had. So don't be so quick to decide you're the victim. You may, in fact, be the perpetrator.