to make excuses by masking own flaws/insecurities by explaining one's own reasoning/actions, often used to avoid the real reason or reality when all it does it make one small, simple & scared.
Joe: Bill why did you beat that guy up?
Bill: cuz he flirted with my girlfriend dude.
Joe: Umm, he was just asking where a store is.
Bill: Well, I had to protect her honor & defend her, besides he looked shifty.
Joe: You're just doing nothing but rationalize.