I'm sure such situations are familiar to many people, especially those who like to think they consider problems from several angles. Bob does something morally reprehensible (cheats on his spouse, kills someone, vandalizes a home, etc). Jane and Mary are discussing the situation, and Jane offers an explanation as to why Bob committed the act (he was sexually frustrated, he was paranoid and thought the victim was watching him, he learned it from his peers). Mary is then upset or angry that Jane would justify Bob's actions. This often happens even though Jane is not actually justifying anything, and agrees that Bob did something wrong - she's only trying to speculate on why he's done what he's done, for curiosity's sake or to help convince any victims that it's not their fault. Yet it would seem that Mary is assuming an explanation for a morally reprehensible action is the same as (or implies) a justification of that action.
That, then, is my question: isn't it easy to disentangle explanations of...